DNV ‘Rules for Planning and Execution of Marine Operations’, 1996.

n
RULES FOR
PLANNING AND EXECUTION OF
MARINE OPERATIONS
CURRENT BOOKLETS
'J
JANUARY 2000
( }
( i
PART 0
Chapter 1
INTRODUCTION
User Infonnation Amend~ents and Indexes ........................................ January 1996
PART!
Chapter 1
Chapter 2
Chapter 3
Chapter 4
GENERAL '
Warranty Surveys .................................................................................. January 1996
Planning of Operations .........................................................................January 1996
Design Loads ............... :........................................................................ January 1996
Structural Design ...............................: ................................................... January 1996
. PART2
Chapter 1
Chapter 2
((
Chapter 3
Chapter 4
Chapter 5
Chapter 6
Chapter 7
( ).
OPERATION SPECIFIC REQUIREMENTS
Load Transfer Operations ...................................................................... January 1996
Towing .................................................................................................. January 1996
Special Sea Transports .......................................................................... January 1996
Offshore lnstallation .............................................................................. January 1996
Lifting ................................................................t..................................January 1996
Sub Sea Operations ............................................................................... J anuary 1996
Transit and Positioning of Mobile Offshore Units ............................... January 2000
DET NORSKE VERITAS
Veritasveien 1. N·1322 H~vik, Norway Tel.: +47 67 57 99 00, Fax.: +47 67 57 99 II
n
DNV - RULES FOR PLANNING AND EXECUTION OF MARINE
OPERATIONS - 1996 REVISION
CORRECTION SHEET No.1
J
o
SEPTEMBER 1996
Please note the following clarifications/corrections to the DNV Rules for Planning and Execution of
Marine Operations.
Pr. l CH.3 DESIGN LoADS llEM 2.3.3.5
The equation for "d" is printed as
d
=1.5 - (1I2j)
The last part of the equation may be misunderstood and is more correctly expressed as;
d = 1.5 - 1/(2j)
Pr.2 CH.6 SUB SEA OPERATIONS. PARAGRAPH 2.3.1
A new item 2.3.1.5 with the following text will be added;
2.3.1.5 The effects of enlrapped air/air cushions shall be
specially considered. Dynamic load effects as well as
changes in buoyancy forces shall be addressed.
Guidance Note
Formulas for loads and load effects in this chapter do not consider
the effects of entrapped alr or air cushions.
Pr.2 CH.6 SUB SEA OPERATIONS llEM 2.3.2.1
Equation 2.6 should be understood as
i.e. the hydrodynamic force is a function of slamming, dynamic effects of buoyancy, drag and inertia
effects.
For combining load components into load cases the following combination is acceptable to DNV;
Rev. OA
Sign. LUND
Page I of3
Fhyd=
(F,lam2 + FP2 + F<ir.1g2 + Fincni.2 )0.5
Slamming loads may be considered as an upward components only, i.e. may be ignored when
estimating maximum crane loads but included when evaluating the possibilities for slack in the
lifting wires. Please note that sideways slamming loads should be considered during local design of
the object.
Pr.2 CH.6 SUB SEA OPERATIONS ITEM 2.3.3.2 .
Formula 2-8 is a curve fitted to numerically calculated slamming velocities. The curve was initially
intended for cases with relatively large crane hoistingllowering velocities. For lowering velocities
close to zero eq. 2-8 will estimate too high slamming velocities. The asymptote value for v, with
)
zero lowering velocities may be taken as;
)
For lowering velocities close to zero, v, may be taken as the least of estimates according to eq 2-8
and the asymptote above.
Pr.1 CH.6 SUB SEA OPERATIONS ITEM 2.3.4.1
This item estimate load components caused by varying buoyancy and dynamics due to waves. A
logical error (mass included rwice through equations 2-4 and 2-9) resulted in unrealistic high load
estimates. It has also been found that certain combinations of crane stiffness, object geometry and
mass properties will provide unrealistic high loads. The item is therefore revised. The revised item
is stated below;
)
2.3.4.1 The lift force component due to varying buoyancy
forces caused by waves may be taken as :
[N]
Eq.2-9
where
H, :
m:
g:
K:
Significant wave height
mass of object in air
acceleration due to gravity 9.81
stiffness of hoisting system see 2.3.4.3
[m]
[kg]
[m/sec']
[N/ml
The F. need not be taken greater than 0.5 times the total
buoyancy of the handled object
Pr.2 CH.6 SUB SEA OPERATIONS ITEM 2.4.2.4
Rev. OA
Sign. LUND
Page 2 of3
Please note a printing error in eq. 2~ 19. The equation should read;
J H,
.
a w -_ 31e-O.32d
Pr.2 CH.6 SUB SEA OPERATIONS ITEM 2.5.2.1
In order to obtain correct estimates of the DAF ac,cording to eq. 2-15, equation 2-22 should read;
(
The static component would otherwise be included twice when estimating the DAF.
)
·0
.,
)
Rev. OA
Sign. LUND
Page 3 of3
n
DNV - RULES FOR PLANNING AND EXECUTION OF MARINE
OPERATIONS - 1996 REVISION
JANUARY 2000
CORRECTION SHEET No.2
()
Please note the following corrections to the DNV Rules for Planning and Execution of Marine
Operations:
)
PT.2 CH.2 TOWING - ITEM 3.1.2
Replace old 3.1.2 with new:
3.1.2
3.1.2.2 The main towing line should for unrestricted
towing have a length not less than;
Main Towing Line
3.1.2.1
For unrestricted towing, the minimum
breaking load (MEL), in tonnes, of the main and spare
towing lines shall be taken according toEq. 3-1.
L,...1ine = 2000 BPIMBL,..,,",
Eq.3-2
3.0BP
(3.64 - 0.8 BP/50) BP
2.2BP
where
BP:::;40
40<BP<90
L,...liDe :
BP:
BP~90
Eq.3-1
miniminn tow line length (m)
continuous static ballard pull of the vessel
in tannes
MBL,....., : towline MBL in tonnes .
where
)
BP :
continuous static ballard pull of the vessel in
lDnnes
3.1.2.3
Towline MBL and minimllI11length less than
required by 3.1.2.1 and 3.1.2.2 may be accepted after
evaluation of:
Guidance Note
BP less than the certified boIlard pull of the vessel
may be
geographical area and tow route,
accepted in Eq. 3-1 for calculation of minimum towiine
strength. provided a corresponding restriction on the ballard
pull ~ . e. towline tension} to be exercised by the tug is specified
in the manual for the actual towing op.eration. Continuous
monitoring of towline tension from the tug's wheelhouse as
specified in 3.3.4.2 should then be possible.
season and possible weather restrictions.
number of tugs and tow spread arrangement,
characteristics of the towed object,
winch design, and
available back-up/contingency.
However, the towline MBL shall never be less than
2BP.
Rev. OF
Sign. RHan
Pagelof2
)
()
PT.2 CH.2 TOWING - ITEM 3.3.2.6
Replace old 3.3.2.6 with new:
3.3.2.6 Required tug bollard pull shall be estimated
based on calculated required towing force and tug
resistance, see 3.3.2.3, 3.3.2.4 and 3.3.2.5, and tug
efficiency in waves.
Unless more accurate calculations or model tests of
towing efficiency of the tug in waves are made, the
continuous bollard pull stated in the bollard pull
certificate shall be multiplied with an efficiency factor
according to Eq. 3-4.
()
o
(.
'Y.. = 0.75(1 - yJ
Eq.3-4
where
'Y.. :
'YL:
L:
rug efficiency factor
tug length fuctor, 'YL = (I - U45)2
rug length (m), not to be taken more than 45 m
Guidance Note
For tugs performing weather routed towing or towing in
protected areaslharbours, a tug efficiency facior according to
Eq. 3-5 below may be used instead of Eq.3-4.
'YTE = (0.B75 • 'YwIB)(1
- 'Y' • 'Yw)
Eq.3-5
where
L:
length of rug (m), not to be taken more than 45 m
'Y, :
tug length factor, 'Y' = (1 • Ll45)'
Hs :
limiting significant wave height .(m) for the weather
routed towing operation, or the probable Significant
)
wave factor,
'Yw = Hsl5
wave height in the protected area/harbour. Hs is not
to be taken less than 1 meter and not more than 5
meter in this equation.
\
i
PT.2 CH.2 TOWING - ITEM 3.3.2.7
Eq. 3-4 to be renumbered Eq. 3-6 . .
)
Rev. OF
Sign. RHan
Page 20f2
-J
DNV - RULES FOR PLANNING AND EXECUTION OF MARINE
OPERATIONS -1996 REVISION
CORRECTION SHEETNo. 3
MAy 2004
&:/~~
7 Knut 0rbeck-Nilssen
!)
Director of Technology - BA Technology Service Staff Functions
Please note the following corrections to the DNV Rules for Planning and Execution of Marine
Operations:
PT.} CR.} SEC. } - PRINCIPLES OF INSURANCE WARRANTY SURVEYS
A new item 1.1.2.2 is added to Paragraph 1.1.2 and hence the existing items 1.1.2.2 & 1.1.2.3 are
renumbered. The complefe revised paragraph 1.1.2 is included below.
1.1.2 Application
(
)
1.1.2.1 These rules describe the formal and technical
requirements which DNV considers necessary for
proper planning and safe execution, of marine
operations.
1.1.2.4 The requirements given in this chapter shall
fonn the basis for Insurance Warranty Surveys in
marine operations but the rules will also be used for
other types of work, e.g. oil companies verification
requirements, see PI.O Ch.1 Sec. 1.2.1.
) .1.2.2 If these rules are used in connection with
planning and execution of marine operations during
removal of offsbore installations the recommendations
in DNV-RP-HI02 (Marine Operations during Removal
or Offshore Installations) shall be considered.
1.1.2.3 The rules apply to Warranty Surveys of all
structures, objects, vessels and equipment, systems and
procedures involved in marine operations. They cover
the range from simple coastal transportations to
complex offsbore installations. They also apply to
evaluation of the selected mode of marine operations in
relation to cargo or object suitability, e.g. with respect
to internal strength or water integrity.
Rev. 2
May 2004
Sign. Alv
Page 1 or I
RULES FOR
PLANNING AND EXECUTION OF
n
MARINE OPERATIONS
PART 0 : INTRODUCTION
PART 0 CHAP1ER 1
USER INFORMATION AMENDMENTS AND INDEXES
JANUARY 1996
SECTIONS
1. INlRODUCTION TO USERS ........ ..... .. . ... .... ... .. .......... ... .. .. .. .. ... ........... ....... ....... ..... ........ . : .... .... 4
.
)
2.
3.
4.
5.
AMENDMENTS AND CORRECTION5.. = ..... .......... ........ .... ..... .... ........... ....... ........... ....... .. ........ 8
DEFINITION OF TERMS ........ .... .. .................. .. .. .... .. .. ................ ............ . .. ..... ......... .. .. . ...... ..... 9
SYSTEMATIC INDEX ......... ...... ........ .. ................. .. . .. .. ...... ....... .. .......... .. .. .. ............... ............ 12
ALPHABETIC INDEX ...... ... . .. .... .............. .. ... . .... .. .. . .. ... . .: ....... . ......... ... .. ... ........ . .. : .. ... . ...... ... .. . 16
DET NORSKE VERITAS
Veritasveien I, N- 1322 HBVik, Norway Tel.: +4767579900, Fax.: +47675799 II
CHANGES IN THE RULES
'This is the first issue of the Rules for Planning and
Execution of Marine Operations, decided by the board of
Det Norske Veritas Classification AlS as of December
1995. These Rules supersedes the June 1985, Slandard
for Insurance Warranty Surveys in Marine Operations.
These Rules come into force on 1st of January 1996.
)
@ Det Norske V~rit.as
Computer Typeselling by Det Norah Veritas
Printed in Norway by the Det Norske Veritas January 1996
1.96.600
'This chapter is valid until superseded by a revised
chapter. Minor revisions to these Rules may be
publicised as supplements to section 2 of this chapter.
Users nre advised to check the systematic index in this
chapter to ensure Ihal chapters are current.
n
Rules for Marine Operations
Pt.O Ch.l User Information Amendments and Indexes
January 1996
Page 3 of 22
CONTENTS
1.
INTRODUCTION TO USERS .•......•......•.. 4
5.
ALPHABETIC INDEX .............•....•....•... 16
1.1
OBJECTIVES OF THESE RULES ............... 4
1.1. 1 General .... ... ....................... . .......... 4
1.1.2 Safety levels ...... .. .... ....................... 4
1.1. 3 Alternative methods .......................... 4
5:1
ALPHABETIC INDEX ................... . ........ 16
5.1.1 General ........................................ 16
1.2
USE OF THESE RULES ........................... 4
1.2.1 Application ................................. ... 4
1.2.2 Conditions for use .............. . ............. 4
1.3
FORMAT OF TIfESE RULES .................... 5
1.3.1 General .......... . .............................. 5
1.3.2 Part 0 .................................... .. ..... 5
1.3.3 Part 1 ...................... ... . ..... ... ......... 5
1.3.4 Part 2 ........................................... 5
1.3.5 Revisions . ...................................... 5
1.3.6 Numbering and cross references ........... 5
1.3.7 Guidance notes ................................ 6
1.3.8 Definitions ........... . ................... , ..... 6
1.3.9 Units ............................................ 6
1.3.10 Indexes .. : ............................ . ........ 6
1.3.11 Tables of contents .. ... ........... ... ........ 6
1.3.12 Reprints from these Rules ................. 6
1.3.13 Marine operation computer programs .... 6
1.4
GUIDEUNES AND NOTES ...................... 6
1.4.1 General .. . ...................................... 6
1.4.2 Guidelines ..................................... 6
1.4.3 Classification Notes ...... . .... .... ...... ..... 6
1.4.4 Certification Notes ................. .. .. ..... . 7
2.
AMENDMENTS AND CORRECTIONS ...... 8
2.1
INTRODUCTION ................................... 8
2.1.1 General ................. . ....... ...... .. ........ 8
2.2
AMENDMENTS AND CORRECTIONS .. .... . 8
2.2.1 GeneraL ........................................ 8
3.
DEFlNITION OF TERMS .• .........•.......•... 9
3.1
DEFINITIONS .. . ................ .. ..... . ... ..... ... . 9
3.1.1 General ........ . ............. ...... .... .. ....... 9
4.
SYSTEMATIC INDEX ..• •. .......•• •....•....... 12
4.1
SYSTEMATICINDEX ............................ 12
4.1.1 General .. ... .. ................................. 12
)
DET NORSKE
Table List
Table l.l - Numbering ... ... . ..... . .......... . ..... .... .... 5
Table 1.2 - Guidelines .. .... .................. .... ..... ..... 7
Table 1.3 - Classification Notes ......................... . 7
Table 1.4 - Certification Notes ............................ 7
VERITAS
Rules for Marine Operations
Pt.O Ch.l User Infonnation Amendments and Indexes
January 1996
Page 4 of 22
n
1. INTRODUCTION TO USERS
1.1 OBJECTIVES OF THESE RULES
1.1.3 Alternative methods
1.1.1 General
1.1. ~.1 The overall objective of these Rules is to ensure
that marine operations are performed within defined and
recognised safety levels.
1.1.1.2 Marice operations are in this context specially
designed, non-routine operations of limited duration
carried out at sea. Marine operations are normally
)
related to temporary pbases of load transfer,
transportation, installation andlor securing of units at
sea.
1.1.3.1 It is the intention that these Rules shall not
inhibit use of the best available theoretical approaches
and practical solutions.
1.1.3.2 Other methods than those described herein may
be used provided quality and safety equivalent or higher
is documented, see 1.1.2.1.
1.1.3.3 Deviations from requirements and
recommendations given in these Rules shall be based on
detailed evaluations of background assumptions, dota,
analysis, theory and practical experience, see also
1.2.2.3.
These Rules does not consider conventional shipping
activities and is not applicable for regular classification
services.
1.2 USE OF THESE RULES
1.1.2 Safety levels
1.2.1 Application
1.1.2.1 Recommendations and guidance aims at a
probability of structural failure equal to, or beller than
1/10000 per operation.
1.1.2.2 Note that above stated probability levels define
a structural capacity reference. Considering also the
probability of operational errors will increase the total
probability of failure.
)
Guidance Note
A review of the Worldwide Offshore Accidental Database (WOAD)
1.2.1.1 These Rules will be used as reference document
and basis for all work performed by DNV related to
marine operations, e .g . verification, advisory. Warranty
Surveys etc. It may however also be purchased for other
applications such as;
for information,
reference standard for single marine operations.
marine specification documentation in relation to
a particular offshore development project, or
general standord specification for a company.
indicate a 40/60 distribution between structural failure and
operational errors. The data material Is however not very distinct
with respect to categorisation of accidental causes. Neither could
any record of total number of marine operations performed be found.
No indication of actual frequency of faHure for marine operations
could hence be established.
1.2.2 Conditions ror use
Guidance Note
scope, objectives and content.
One of the objectives for these Rules were to include probabilities of
operational errors when assessing marine operations. Any
background data to support such approach could however not be
found. DNV will seek to include an overall probability of failure as
soon as reliable statistical data of operational records are available.
An probability of total loss equal to, or better than 1/1000 per.
operation will then be aimed at.
1.1.2.3 Recommendations and guidance are as far as
aD statistical methods. Where
relevant statistical data have not been available, or
recommendations based on a statistical approach have
possible given based
not been developed, given requirements are based on
1.2.2.1 Users of these Rules should be familiar with its
1.2.2.2 The user agrees that application of these Rules
shall be at the users sale risk, and accept by use that
DNV's liability for claims arising from omissions, faults
or inconsistencies in these Rules shall be limited to the
amount charged for tbese Rules.
1.2.2.3 DNV disclaims aoy liability and/or
responsibility resulting from any or all deviations from
given requirements and/or recommendations unless such
deviations have been approved by DNV beforehand.
recognised codes, standards and "industry practice".
"Industry practice" is defined as methods and practice
commonly accepted and recognised by the branch .
DET NORSKE VERITAS
(
Rules for Marine Operations
January 1996
~ _PL~O_C~h~.~I~U~s~e~r~~~o~nn==a=ti=o=n~Arn==e=n=Wn~e=n=~~a=n=d~In=d=ex=es~________________________________-!P~ag~e~5~o~f~2~2
1.3 FORMAT OF THESE RULES
1.3.5 Revisions
1.3.1 General
1.3.5.1 Revisions to these Rules will be included based
on proposals from the staff of this Society, insurance
1.3.1.1 The format of these Rules is choseo to allow for
easy maintenance and updating. It is our objective that
proven and sound engineering and operating practice, up
companies. oil companies, engineering companies ,
marine operators or other parts involved in marine
operations. Proposals will be assessed based on practical
to date technological and operational developments at all
times shall be reflected in these Rules.
experience. theoretical studies, research and
1.3.1.2 The Rules for Planning and Execution of
Marine Operations are published in tllree parts. Each
part consist of chapters appearing as separate booklets.
decision is made.
The three parts are;
Part 0, Introduction
Part 1, General Requirements, and
development. These proposal will normally be subject
for internal and external hearings before a formal
1.3.5.2 Revisions may be undertaken at any time, but
will normally be published January each year. Revisions
will be forwarded to registered users of the Rules as
revised chapters or as supplements to Sec.2. of this
chapter.
Part 2, Operation Specific Requirements.
o
1.3.2 Part 0
1.3.2.1 This part provide brief instructions to users and
present the general format of the Rules. Systematic and
alphabetic indexes and a list of corrections are included
as well.
1.3.2.2 Format and editorial details of the Rules are
described.
1.3 . 5~3 This chapter and the chapter list enclosed as
front page in the ring binder state current status of the
Rules in form of latest revision date for each chapter. It
is important that the user check that the date on the front
page of the relevant Rule chapters corresponda with
those given in these lists.
1.3.5.4 Revision. to latest edition of each chapter will
be stated on the second page of the respective chapter.
1.3.6 NwnberinJ! and eross references
1.3.3 Part 1
1.3.3.1 Pr.l Gil. 1 defines requirements, roles, basis for
work and the procedure to be followed if DNV is
engaged as Warranty Surveyor.
1.3.3.2 Pt. 1, GII.2 through GilA give general
o
requirements and recommendations for planning,
preparations of marine operations as well 8S
environmental conditions, loads. load effects, load
combinations and structural verification to be
considered.
1.3.6.1 Numbering according to Table 1.1 are used
throughout these Rules.
.
T
abie l l - Nwnberinl!
..
. ., .. .:...:;.. ...
"
"
4vel . ' ..
Parts
Chapters
..
Sections
Sub·Sections
Paragraphs
Items
' ;"."
N,ll~V;~~o
Pt.1
Ch.1
1.
1.1
1.1.1
1.1.1.1
1.3.6.2 Cross references between chapters in Pt.2, and
from Pt. 1 to Pt.2 are sought avoided.
1.3.4 Part 2
1.3.4.1 This part give specific requirements for
different types of marine operations. Requirements in
Pt. 2 are based oli the general requirements in Pt. 1.
References back to this part are extensively used.
1.3.6.3 Cross references are made according to the
following fonnat;
between chapters: see Pt. 1 GII.1 Sec. 1.1
within a chapter: see also 1.1.1.
1.3.6.4 Cross references are written in italic style.
DIIT NORSKE VERlTAS
n
January 1996
Page 6 or 22
Rules for Marine Operation
Pt.O Ch.1 User lnfonnation Amendments and Indexe
1.3.7 Guidance notes
1.3.13 Marine operation computer programs
1.3.7.1 Guidance notes are included where additional
1.3.13.1 A software package supporting formulas and
methods specified in these Rules is planned. Users of
these Rules will be notified when this package is
released, and informed of subsequent updates.
advice, formulas, experience, practises, explanations etc.
may be applicable.
1.3.8 Definitions
1.3.8.1 Definition of terms are included in this chapter.
Definitions of terms considered to be of particular
importance for the respective chapters are repeated in·
these.
1.3.8.2 All symbols used within a chapter are listed in a
symbol list at the beginning of each chapter.
1.4 GUIDELINES AND NOTES
1.4.1 General
1.4.1.1 In an effort to aid the parties involved in marine
engineering and classification of ships, DNV has issued
Guidelines and Classification Notes giving practicnI
information regarding classification and other relevant
regulations as well as guidance in new fields of
technology. These publications are available on a
1.3.9 Units
)
1.3.9.1 These Rules generally uses SI-units. When
other units are used these are particularly stated.
purchase or subscription basis.
1.4.2 Guidelines
1.3.10 Indexes
)
1.4.2.1 Guidelines are publications which give
1.3.10.1 A systematic and an alphabetical master index
information and advice on technical and formal matters
have been prepared for the complete Rules. These are
presented in Sec.4 and 5.
related to the design, building, operation, maintenance
and repair of vessels and other objects, as well as the
services rendered by the Society in this connection.
1.3.10.2 The systematic index gives references to
Aspects concerning classification may be included in the
publication.
sections and subsections within each part/chapter
whereas the n!phabetic index gives references to the page
number within the appropriate part/chapter, e.g. Pt.l
Ch.l pI. Note that pages in each chapter are numbered
from J.
A list of Guidelines that may be relevant for marine
operations is given in Table J. 2.
1.3.11 Tables of contents
1.4.3.1 Classification Notes are publications which give
1.3.11.1 Two tables of contents levels are included at
the beginning of eacb chapter. A table of sections on the
front page of tbe chapter, providing the starting page
number of eacb section, and a table of content including
sections, subsections and paragraphs.
1.4.3 Classification Notes
practicn! h.formation on engineering/design aspects in
genernl, and on classification of ships and other objects
in particular. Examples of design solutions, cnIculation
methods specifications of test procedures, as well as
acceptable repair methods for some components are
given as interpretations of the more general rule
requirements.
1.3.11.2 List of figures and tables in the chapter are
included after the table of contents.
A list of Classification Notes that may be relevant for
marine operations is given in Table 1.3.
1.3.U Reprints from these Rules
1.3.U.l Reprints from the Rules are available from tbe
Society on request. There is currently no SUbscription
scheme for reprints. No special notification of
amendments to buyers of reprints will be made.
DET NORSKE VERITAS
Rules for Marine Operations
Pl.O Ch.1 User Infonnation Amendments and Indexes
1.4.4 Certification Notes
1.4.4.1 Certification Notes are publications which
contain principles , accept criteria and practical
information related to the Society's consideration of
objects, personnel , organisations, services and
operations, in connection with issuance of certificates or
declarations, which are not necessarily related to
classification.
A list of Certification Notes that may be relevant
marine operations is given in Table 1.4.
Table 1 2 - Guidelines
':No, ' . Title','.:'.'"
.:.... "
4.
o
10.
/',i""
.,
\.;-:
fOT
.
:....
~~;.::,.: ~:' . ':. ,-:'';i
Stability Documentation for Mobile Offshore
Units Class and Starutory Services , November
1986.
DNY Recommended Reporting Principles for
Ultrasonic Thickness Measurement of Hull
Structures, September 1993.
Table 1 3 - Classification Notes
,.
"
.. No.
7
: ' Tit!O: '
.,
.. ,.:., .:
.. ,",
:'-:'-.1'.' ..
Ultrasonic Inspection of Weld Connections, May
1980. (Reprint of November 1978.t
20. I"
Stability Documentation - Ships Newbuildings,
30.1
30.2
February 1990.
Bucklin. Strength Analysis, May 1992.
Fatigue Strength Analysis for Mobile Offshore
Units, August 1984.
30.3
30.4
30.5
30.6
Spherical Shells Subjected to Compressive
Stresses, October 1987.
Foundations February 1992
Environmental Conditions and Environmental
Loads, March 1991.
Structural Reliability Analysis of Marine
Structures, july 1992.
Table 1 4 - Certification Notes
..
~. ;:
:No. 'I 'fitle
Series No.2 Approval Schemes
Certification of Offshore Mooring Steel Wire
2.5
Rope (May 1995).
Certification of Offshore Mooring Chain (August
2.6
1995).
- ','
')
,
DEI' NORSKE VERITAS
January 1996
Page 7 of22
January 1996
Page 8 of22
Rules for Marine Operations
Pt.o Ch.1 User lnfonnation Amendments and Indexes
2. AMENDMENTS AND CORRECTIONS
2.1 INTRODUCTION
2.1.1 General
2.1.1.1 This section includes approved amendments and
corrections which are not yet incorpomted in the
respective cbapters.
Information on tbe coming into force date of new
amendments are given on the cover inside of this
Introduction cbapter.
In addition correction of misprints and clarification of
the text may be included.
()
2.2 AMENDMENTS AND CORRECTIONS
2.2.1 General
2.2.1.1 This issue of tbe Rules for Planning and
execution of Marine Opemtions is the first issue of the
Rules. Hence there are no amendments or corrections to
this first revision of the updated Rules.
)
o
(J
DEl' NORSKE VERITAS
Rules for Marine Operations
Pt.O Ch.l User Infonnation Amendments and Indexes
January 1996
Page 9 of22
I
3. DEFINITION OF TERMS
3.1 DEFINITIONS
structural elements which includes relevant load factors,
consequence factors, and local dynamics.
3.1.1 General
Design life: The period of time from commencement of
3.1.1.1 Terms used in these Rules are dermed below.
Definitions of terms considered to be of particular
importance for the respective chapters are repeated in
these.
)
o
Assured : The party who has obtained an insurance cover
for the marine operation and who eogages the Warranty
Surveyor in order to ensure that the terms of the
warranty as laid down in his Insurance Policy are
complied with. This may be the Operator/Company or
construction to condemnation of the structure.
Design load : Load used in the design of a structure,
i.e. characteristic load mUltiplied by the load coefficient.
Design load effect: The load effects calculated on the
basis of the design load.
Desigll resistallce: The resistance to be used in the
safety evaluation of a structure or part of a structure,
i.e., characteristic resistance divided by the material
coefficient.
the Contractor.
Design sea state: The short term. wave condition which
form basis for the design and design verification.
Bobbin: Sheaves applied to increase the bepding
diameter of double slings around a pin.
Bollard pull: Continuous static towing force applied by
tug, i.e. continuos tow line force
Cable laU grommet: Steel or fibre ropes arranged into a
stranded construction, cabled together, right or left lay,
and spliced such that there is no end.
Cable laid sling: Steel or fibre ropes arranged into a
stranded construction, cabled together, right or left lay,
with a spliced eye in each end.
Cenified item: Item with a capacity or property certified
by a recognised body.
Characteristic condition: A condition which, together
with load and material factors, render a defined
probability of exceeding structural capacity within n
defined time period.
Characteristic load: The value of a randomly variable
load that has an agreed probability of exceedance under
actual conditions within an agreed time , period.
,
Characteristic resistance: The value of resistance that
has an agreed probability of exceedance.
Design srrength: The material strength to be used in the
deten;ninatioD of the design resistance of a structure or
part of a stIllcture, i.e., characteristic strength divided
by the material coefficient.
Dynamic amplification factor : A factor accounting for
the global dynamic effects normally experienced during
lifting. The dynamic amplification factor is defined as
(Dynamic load + Static Load)/ Static Load.
Fail safe: A configuration which upon failure of
elements remain in a controllable and safe condition.
Fibre sling : Slings made of high performance man made
fibres.
Float out: 'The activities necessary to transfer an object
from ·a dry construction site to a self floating condition
outside the construction site.
Grillage: Structural load distributing elements installed
to avoid excessive local loads.
Grommet: Endless sling.
Coastal towing: Towing in waters less than 12 nautical
miles of the coast line.
Grouting: The activities necessary for cementing the
void spaces between pile and pile sleeve after pile
driving or the provision of even foundation support for
an object placed on the sea bottom by injection of
Contractors: The parties performing the actual work.
cement under the base structure,
Design: An activity to create or form layout's,
Gust wind: Average wind speed during a specified time
interval less than one minute
concepts, arrangements Of structures.
Design criteria: The criteria applied for verification of
systems, equipment, structures etc. for the planned
marine operation.
Design factor: Factors to be applied for design of
Heavy lift carrier: A submersible barge or vessel
carrying heavy object on deck. The objects are
loaded/off-loaded the carrier by Iloat on/Iloat off
operations.
DET NORSKE VERITAS
January 1996
Page 10 of 22
Rules for Marine Operations
Pt.O Ch.1 User lnfonnation Amendments and Indexes
Heavy lift carrier transports: Transfer at sea from one
location to anotber of an object by a beavy lift carrier.
object from one support condition to another.
Independent third party verification : Verification
activities performed by a body independent from
conditions are non-stationary.
Marine Operation Declaration: A written confirmation
stating compliance with this Standard of equipment,
temporary and permanent structures, bandied object,
company and contractor.
Inshore towing: Towing in sheltered waters.
Insurer: The party wbo is providing insurance cover for
the marine operation.
Internal seajastening : Securing of loose items within tbe
bandied object.
Launching : An activity comprise cutting of seafastening
of an object resting on a specially equipped launch
barge, tbe object's slide down the skid beams on the
barge and diving into the water until the object is free
floating.
Lift off: The activities necessary to transfer an object
positioned on land or sea bed supports into a floating
condition.
Lift Oil: A reversed lift off. I.e. the activities necessary
to transfer an floating object onto land/sea bed supports.
procedure, preparations etc.
Mating: The activities necessary to join two floating
objects. The floating objects may be supported by
barges, pontoons, etc.
Mean wind velocity: The average wind velocity within
a speci lied time interval .
Multi barge towing: Transfer at sea from one location to
anotber of an object resting on two or more barges by
use of tugs.
Natural period: The period of whicb the vessel will
move in still water.
Object: The object handled during tbe marine operation,
typically a module, deck structure, jacket, sub sea
structure, pipes, other equipment.
Lift points: The attachment points for slings on tbe
lifted object. Lift point are normally designed as
padeyes or padear/trunnions.
Offshore towing: Towing in waters more tban 12
nautical miles of tbe coast line.
Lifted object : A structure or parts thereof subjected to
lifting.
start- and termination point.
Lifting : The activities necessary to lift or assist an object
by crane or cranes.
Lifting equipment: Temporary installed equipment sucb
as slings, shackles, sheaves, spreader beams or frames,
necessary to perform the lift.
)
Long tenn : A period of time where environmental
Limit state: A state in whicb a structure ceases to fulfil
the function, or to satisfy the conditions, for which it
Operation: A planned marine operation, with defmed
Operation criteria: The acceptance criteria for start of
tbe planned operation.
Operation reference period : The time period to be used
in establishing tbe cbaracteristic value of a random
parameter used as the basis for the design.
Operator/Company: The party representing tbe
owner(s).
structure.
Padear : Lifting point on a structure consisting of a
tubular member with a stopping plate at the end. The
sling/grommet may be laid around tbe tubular member
such tbat a sbackle is not needed.
Laad coefficient: Coefficient by whicb tbe
characteristic load is multiplied to obtain the design
load.
Padeye: Lift point on a structure consisting of a steel .
main plate witb a matched bole for tbe sbackle pin. The
bole may be reinforced by a plate (cbeek plate) on eacb
was designed.
Laad : Any action causing stress or strain in tbe
Laad effect: Effect of load on tbe structure, such as
stresses and stress resultants (internal forces and
moments), strain, deflections and deformations.
Laad in : The activities necessary to transfer an object
from a vessel to land, i.c. a reversed load out.
Laad out: The activities necessary to transfer an object
from land onto a vessel by a borizontal movement of the
object.
Load transfer: The activities necessary to transfer an
side.
Piling: The activities necessary to secure an object to
the sea bottom by driving piles into the sea bottom.
Plate shackle: A sbackle where the bow is replaced by
two steel plates and an extra pin.
Positioning: The activities necessary to position an
object at a certain predeternained location.
Recognised code or standard: National or international ,
code or standard, which is recognised by the majority of
DET NORSKE VERITAS
Rules for Marine Operations
Pt.O Ch.l User Infonnation Amendments and lndexes
professional people and institutions in the marine and
offshore industry.
Rigging arrangement: The complete system, as
applicable, of slings, shackles and, spreader beams or
frames.
Safe condition: A condition where the object is
considered exposed to "normal" risk for damage or loss.
Seafastening : Structural elements providing horizontal
and uplift support of object during towing operations.
SelfjIoating towing: Transfer at sea from one location
to another of an object supported by its own buoyancy
and pushed! pulled by tugs.
Setting: The activities necessary to set-down an object
on the seabed after positioning, including levelling, and
) soil penetration and suction (if applicable).
Shackle: A structural component composed by a bow
and a pin linking a sling/grommet to a padeye.
o
Ship transportation: Transfer of an object at sea from
one location to another of an object onboard a
conventional vessel or supply vessel.
Short tenn: A period of time wherein statistical
environmental parameters may be assumed stationary.
NoniIally 3 or 4 hours.
Short tenn wave condition: A wave condition where
object.
Trunnion: Lifting point on a structure consisting of a
tubular member with a stopping plate at the end. The
sling/grommet may be laid around the t:ubular member
such tbat a shackle is not needed.
Unit: The assembled configuration of transport barges
and object to be transported.
Unrestricted operations: Operations with characteristic
environmental conditions estimated according to long
term statistics.
Upending: The activities necessary to upend a floating
object.
Verification: Activity to confirm that a design,
product/equipment, structure or procedure complies with
defined standards andlor specifications. Verification
may be documented by calculations, analysis,
certificates,~urvey
VMO: Verilas Marine Operations, a product offered by
DNV. The product responsibility is assigned to a
specific DNV organisational unit.
Warramy surveyor: The independent third party
ensuring that the terms of the Marine Insurance
Warranty Clause is complied with ..
Wave height: The crest to trough beight.
significant wave height and zero crossing wave period
Weather restricted operations: Operations with defined
restrictions to the characteristic environmental
Single cricical element: Non-redundant element, which
failure constitute failure of the struct:ure/system.
conditions, planned performed within tbe period for
reliable weather forecasts.
Zero crossing wave period: Average wave period, i.e.
average time period between water surface elevate
through the still water level.
Site move: The activities necessary to transfer an object
from one location at the yard to another.
Skew load factor: A factor accounting for the extra
loading on slings caused by the effect of inaccurate sling
lengths and other uncertainties with respect to force
distribution in the rigging arrangement.
Sling: A strap used between liftpoint and crane hook
during lifting. The term sling is also used for a steel
rope witb an eye at each end.
Snap force: Snatch load in hoisting line due to sudden
velocity cbange of lifted object.
)
reports and inspection reports.
are assumed constant in the duration time, typically 3
hrs.
Significant wave: Four times the standard deviations of
the surface elevation in a short term wave condition
(close to the average of the one third highest waves).
0 )
January 1996
Page 11 of22
Spreader beamlframe : Part of tbe rigging which may
transfer compression loads. It may be applied to;
avoid horizontal loads to the lifted object,
reduce the effect of inaccurate sling lengths or
to avoid clashes between slings and the lifted
DET NORSKE VERITAS
.
January 1996
Page 12 of22
Rules for Marine Operations
Pt.O Ch.1 User Information Amendments and Indexes
4. SYSTEMATIC INDEX
3.
4.1 SYSTEMATIC INDEX
4.1.1 General
4.1.1.1 Below systematic master index has been
prepared for the Rules. The systematic index includes
sections and subsections within each part/chapter
Part 0 Chapter 1
USER INFORMATION AMENDMENTS AND
INDEXES
January 1996
)
1.2
1.3
1.4
Introduction to Users
Use of this Standard
Format of this Standard
Guidelines and Notes
2.
2.1
2.2
Amendments and Corrections
Introduction
Amendments and Corrections
I.
3.1
Definition of Terms
Definitions
4.
4. 1
Systematic Index
Systematic Index
5.
Alphabetic Index
Alphabetic Index
3.
3.1
3.2
3.3
3.4
3.5
3.6
Part 1 Chapter 2
PLANNING OF OPERATIONS
January 1996
1.
1.1
1.2
Introduction
General
Definition
2.
2.1
2.2
2.3
2.4
Planning
Planning Principles
3.
5. 1
3.1
3.2
3.3
3.4
3.5
Part 1 Chapter 1
WARRANTY SURVEYS
January 1996
,
Procedures For Insurance Warranty Surveys
Engagement of The Warranty Surveyor
Basis for Work
Approval Work
Preparation for Operations
Attendance during Operation
Needs and Duties of Parties Involved
I.
1.1
1. 2
1. 3
1.4
1.5
1.6
Principles of Insurance Warranty Surveys
Introduction
Basic Definitions
Marine Insurance Act
Purpose of Insurance Warranty Surveys
Marine Operation Declarations
Breach of Warranty
2.
2. 1
2.2
2.3
2.4
2.5
2.6
Scope of Insurance Warranty Surveys
Warranty Clause
Warranty Surveyor Tools
Warranty Level
Risk Assessment
Reduced Scope of Warranty
Extended Scope of Warranty
Documentation
Risk Evaluations
Marine Operation Declaration
Operational Itequirements
Operation and Design Criteria
Weather Forecast
Organisation
Preparation and Testing
Marine Operation Manual
4.
4.1
4.2
4.3
4.4
4.5
Stahility Requirements
General Requirements
Barge Transports
Self Floating Structures
Load Out Operations
Other Vessel
5.
Systems And Equipment
System Design
Vessels And Barges
Mooring Systems
Guiding And Positioning Systems
5. 1
5.2
5.3
5.4
DET NORSKE VERIT AS
Rules for Marine Operations
Pl.D Ch.l User lnfonnation Amendments and Indexes
Part 1 Chapter 3
DESIGN LOADS
January 1996
1.
1.1
1.2
Introduction
General
Definitions
2.
2.1
2.2
2.3
2.4
Enviromnental Conditions
General
Wind Conditions
Wave Conditions
Corrent And Tide Conditions
3.
Loads and Load Effects
Load Categories
Load Analysis
Wave Loads
Wind And Current Loads
Static Loads
Hydrostatic Loads
Restrain Loads
Accidental Loads
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
Part 1 Chapter 4
STRUCTURAL DESIGN
Januar 1996
1.
1.1
1.2
Introduction
General
Definition
2.
2.1
2.2
2.3
Design Principles
Design Considerations
Load Cases
Design Analysis and Criteria
3.
3.1
3.2
3.3
Design Verification
Verification Methods
Strength Verification
Testing
4.
Resistance and Materials
4.1
4.2
Structural Resistance
Materials And Fabrication
Part 2 Chapter 1
LOAD TRANSFER OPERATIONS
January 1996
1.
1.1
1.2
1.3
Introduction
General
Design Phase
Operational Aspects
January 1996
Page 13 of 22
2.
2.1
2.2
2.3
2:4
2.5
2.6
2.7
2.8
Load Out
General
Loads
Loadcases and Analysis Of Forces
Structures and Soil
Systems and Equipment
Load Out Vessel
Operational Aspects
Special Case
3.
Float Out
Introduction
Loads
Loadcases and Analysis Of Forces
Structures
Systems and Equipment
Operational Aspects
3.1
3.2
3.3
3.4
3.5
3.6
4.
4.1
4.2
4.3
4.4
4.5
4.6
4.7
5.
5.1
5.2
5.3
5.4
5.5
5.6
6.
6.1
6.2
6.3
6.4
6.5
LiftOff
General
Loads
Loadcases and Analysis Of Forces
Structures
Systems and Equipment
Lift Off Vessels
Operational Aspects
Mating
Introduction
Loads
Loadcases and Analysis Of Forces
Structures
Systems and Equipment
Operational Aspects
Construction Alloat
Introduction
Loads
Stability Afloat
Mooring
Operational Aspects
Part 2 Chapter 2
TOWING
January 1996
I.
1.1
1.2
2.
2.1
2.2
2.3
Introduction
General
Definitions
Planning and Preparations
Planning
Design
Structural Design Calculations
DET NORSKE VERIT AS
January 1996
Page 14 of 22
3.
3.1
3.2
3.3
4.
4.1
4.2
Towing Equipment
Towing Arrangement
Barges
Towing Vessels
Towing Operations
Tow Out
Towing
Part 2 Chapter 3
SPECIAL SEA TRANSPORTS
January 1996
1.
1.1
1.2
Introduction
General
Definitions
2.
Ship Transportation
Planning and Preparations
Operation
2.1
2.2
3.
3.1
3.2
3.3
4.
4.1
4.2
4.3
5.
5.1
5.2
Multi Barge Towing
Planning and Preparations
Towing Equipment
Towing Operations
Self Floating Towing
Planning and Preparation
Towing Equipment
Towing Operations
Heavy Lift Carriers
Planning and Preparations
Operational Aspects
Part 2 Chapter 4
Rules for Marine Operations
Pt.O Ch.l User Information Amendments and Indexes
4.
4. 1
4.2
4.3
4.4
4.5
Upending
Introduction
Loadcases and Analysis Of Forces
Structures
Systems
Operational Aspects
5.
5.1
5.2
5.3
5.4
5.5
5.6
Positiouing and Setting
Introduction
Loadcases and Analysis Of Forces
Structures
Systems
Docking
Operational Aspects
6.
6.1
6.2
Piling and Grouting
Introduction
Operational Aspects
Part 2 Chapter 5
LIFfING
January 1996
1.
1.1
1.2
1.3
General
Introduction
Definitions
Miscellaneous
2.
2.1
2.2
2.3
2.4
Loads
Basic Loads
Pynaruic Loads
Skew Loads
Loadcases and Analysis Of Forces
3.
Lifting Equipment
Slings and Grommets
Shackles
3.1
3.2
OFFSHORE INSTALLATION
January 1996
1.
1.1
1.2
1.3
Introduction
General
Definitions
Installation Site
2.
2.1
Loads
Environmental Loads
3.
3.1
3.2
3.3
3.4
3.5
3.6
Launching
Introduction
Loadcases and Analysis Of Forces
Launched Object
Launch Barge
Systems and Equipment
Operational Aspects
4.
4.1
4.2
Structures
Design Conditions
Fabrication and Inspection
5.
Lift Operation
5.1
5.2
Crane and Crane Vessel
Operational Aspects
6.
Yard Lifts
General
Loads
Lifting Equipment
Structures
Cranes
Operational Aspects
6. 1
6.2
6.3
6.4
6.5
6.6
DIIT NORSKE VERITAS
Rules for Marine Operations
Pt.O Ch.1 User Infonnation Amendments and Indexes
Part 2 Chapter 6
SUB SEA OPERATIONS
January 1996
1.
1.1
1.2
1.3
1.4
1.5
Introduction
General
Definitions
PlllIIIting
Loads
Structures
2.
2.1
2.2
2.3
Design Loads
General
Crane Tip Motions
Hydrodynamic Forces when Lowered through
Water Surface
Hydrodynamic Forces on Submerged Objects
Snap Forces in Hoisting Line
Other Loads
2.4
) 2.5
2.6
3.
Soil Capacities
3.1
3.2
On Bottom Stability
Pull Out Forces
4.
4. 1
4.2
4.3
4.4
4.5
4.6
Operational Aspects
General
Systems
Installation Aids
Rov Operations
Tie-In Operations
Bundle Operations
Part 2 Chapter 7
TRANSIT AND POSITIONING OF MOBILE
OFFSHORE UNITS
HOLD
DET NORSKE VERITAS
January 1996
Page 15 of 22
January 1996
Page 16 of 22
Rules for Marine Operations
Pt.O Ch.1 User Infonnation Amendments and Indexes
5. ALPHABETIC INDEX
5.1 ALPHABETIC INDEX
-C5.1.1 General
5.1.1.1 Below alphabetic master index has been
prepared for the complete volumes of the Rules.
5.1.1.2 The format of the alphabetic index is as
follows;
)
< main index > . < sub-index> . < PI., Ch.
ref.> <page>.
-AAccidental case
structural design .......................................... .. Pl.l ChA p6
Accidental loads... .......... ........ ... ... .................... Pt.l Ch.3 P 17
dropped objects ........................................... Pt.1 Ch.3 p17
vessel collision ............................................ Pt.! Ch.3 pl7
advisory service ....... ............. ... ....................... Pt. I Ch.1 p9
Alternative methods ............................................ Pt.O Ch.! p4
Amendmeots to the Standard ..... ......................... Pt.O Ch.! p8
Application of the Standard ......................... ....... PtO Ch.! p4
-BBallast system
back up... ... ................ ... ...... ... .... ... ............... Pt.2 Ch.1 P II
capacity ............................... Pt2Ch.1 p20. Pt.2Ch.1 pll
)
~:f:i:::.: : : : :·: :.: .· ·: .: .: . : .·:: : : : : :.: : : :: E:~g~:: m
Barges
access ....... .................. ..... .... ... .... ......... .... ...... Pt.2 Ch.2 p9
anchoring and mooring equipment.. ............... Pt.2 Ch.2 p9
ballast systems ................. ........ ..................... Pt.2 Ch.2 p9
corrosion ............................... Pt.2 Ch.2 p6. Pt.l Ch.2 p20
geneml requirements .......... ............. ......... ... Pt.l Ch.2 P 19
global strength ............................................... Pl2 Ch.2 p7
inspection and testing .............. ...................... Pt.2 Ch.2 p9
local strength ................................................. Pt.2 Ch.2 p7
Bumpers ................... ............... ............. ............ Pt.l Ch.2 p22
Bundle pull in ........ .......................................... Pt.2 Ch.6 pl8
Bundle towing
bottom survey .............. .......... ...................... Pt.2 Ch.6 p17
internal strength .......................................... Pt2 Ch.6 pl8
tug momtonng ............................ ............... .. Pt.2 Ch.6 pl8
tug reqUIrements .......................................... Pt.2 Ch.6 pl7
Buoyancy...... .... ....... ........ ........ ..... ............ ........ Pt.l Ch.3 P 16
)
Centre of gravity ............................................... Pt. I Ch.3 pl6
CertIficates
s~ackles ........ ........................................ ....... Pt.2 Ch.5 piS
s mgs ............................... ............................ Pl2 Ch.S p13
Characteristic conditions ......... ...................... ...... Pt.1 Ch.3 p6
Clearances
float out ................... .. ........................ ....... ... Pt.2 Ch.1 p 16
lift off .......................................................... Pt.2 Ch.1 p22
mating ............................. '" .................. ........ Pl.2 Ch.1 p26
multi barge transports ............ ......................... Pt.2 Ch.3 p9
Commisioning
program' .. ...................... ............................... Pt.1 Ch.2 P13
Communication ................................................. Pt.l Ch.2 pl2
testing ........................................... ............... Pt.1 Ch.2 P13
Conditions for use ........ ..................................... .. Pt.O Ch.1 p4
Construction alloa!... .......................... ............... Pl2 Ch.1 p27
freeboard ....................................... ..... .... ...... Pt.2 Ch. 1 p27
inclination tests ............................................ Pl2 Ch.1 p27
loads........................................................ .... Pt.2 Ch.1 p27
moormg ........................................................ Pl2 Ch.! p27
mooring equipment ....... ............................... PL2 Ch.1 p28
. ....... ............................................. ... Pt.2 Ch.1 p27
p Ianrung
stability afloa!... ................................ ........... Pl2 Ch.1 p27
Corrections to the Standard ................................. PlO Ch.1 p8
Corrosion
existing structures ........... ............................... Pt.! ChA p6
Cmue vessel... ................................. .................. Pl2 Ch.S pl8
crane documentation........ :.. .......................... Pl2 Ch.S pl8
load monitoring ............................................ Pt.2 Ch:S pl8
vessel documentation ..... .............................. Pl2 Ch.5 P18
Carrent loads .................................................... Pt.l Ch.3 piS
-D-Declarations
~nmplex operations ............................ .......... Pll Ch.1 P II
~:::~e~~~:::::::::::::::::::::::::::::::::::::::::::::::::: ~:: g~:: ~~
review scope .................................................. Pt.1 Ch.2 p9
scope ......................................... ................ ..... Pt. I Ch.2 p9
Defmitions ...................... ...... .............................. Pt.O Ch.1 p9
Design analysis
analytic models .............................................. Pt. I ChA p8
failure modes ................................................. Pt.1 ChA p8
principles ............................ .......................... . Pt.l ChA p8
Design Basis ................... .............................. ...... Pt. I Ch.2 p7
Design BrieL. ..................................................... Pt.l Ch.2 p7
Design loads
load cases ....................................................... Pl.I ChA p7
load combinations ................ ..... ..................... Pt. I ChA p7
Design methods ........... ................. ................... .... Pt. I ChA p8
partial coefficicnt.. ......................................... PI. I ChA p9
permissible stress .. ......................................... Pt. I ChA p9
prob abirIS fIC ••••.•••••..••..••..•.•••••••.••••••.•......••...•. Pt. I ChA p9
DET NORSKE VERlTAS
c
Rules for Marine Operations
Pt.O Ch.l User lnfonnation Amendments and Indexes
January 1996
Page 17 of 22
Documentation
inpul documentalion ......... ....... ........ .... ...... .... Pt.1 Ch.2 p8
operation manual ......................................... Pl. I Ch.2 p13
operation records .................................... '" .... Pt.1 Ch.2 p8
oulput documentaion ..................................... Pt.! Ch.2 p8
quality requirements .......................... ............ Pl.I Ch.2 p8
Dynamic amplification factor
lifting .... ........................................................ Pt.2 Ch.S p7
-E-Environmen~1
conditions
currenL .... .................. ................................. PLi Ch.3 plO
environmental phenomena ......... ..... ..... .......... Ptl Ch.3 p6
gust wind... ......... ...... ... ............ ..... ....... .. ....... . Pt.1 Ch.3 p8
local conditions ............................ ................. PLI Ch.3 p7
moniloring ................................................... Pli Ch.2 p12
swell ...... ..................................... ................ Pt.1 Ch.3 plO
tide varialions .............................................. Pt.1 Ch.3 pi I
waves. ... ... ....... ... ......... ... .................. ..... ... ..... PLI Ch.3 p8
wind ...................................................... ........ PLI Ch.3 p7
Environmental statistics ................... ................... Pt.! Ch.3 p6
seasonal variations ......................................... Pl.! Ch.3 p7
-F-
Hazap ................................................................. Pl. I Ch.2 p9
Heavy lift carriers .............................................. Pt.2 Ch.3 pl2
analysis of molions .. ........................ ............. Pt2 Ch.3 pl2
cribbing ......................................... ..... .......... Pl.2 Ch.3 p!2
guides .......................................................... Pt.2 Ch.3 pl2
on- and off-loading ....................................... Pt.2 Ch.3 p13
operational aspects ......................... ...... ... ..... Pt.2 Ch.3 p13
seafastening inspection ...........•..................... Pl.2 Ch.3 p13
self propelled carriers ............... .................... Pt.2 Ch.3 pl2
structural design verificalion ........................ PL2 Ch.3 P 12
transport manual .......................................... Pt.2 Ch.3 P 13
Hydrodynamic loads
splasb 20ne.................._........... ....................... Pl.2 Ch.6 p9
submerged structures .................................... Pt.2 Ch.6 p!O
Hydrostatic loads............................................... Pl.l Ch.3 pl6
-1Inclination test
construction nfloal... ..................................... Pt.2 Cb.1 p27
Index
alphabelic .............................. Pt.O Ch.l pIS. Pl.O Ch.l p6
systematic .............................. Pt.O Ch.l p!2. Pl.O Ch.l p6
Infonnation to users
Fabrication
elemenl calegaries ....................................... Pl.I ChA pl4
maleria! qunlities ................. ........................ Pt.1 ChA pl4
lolerances.. ........... ....... ...... ..... .................. ... Pl.! ChA P 14
welding consumables .......... ......................... Pl.I ChA piS
Faligue limit stale
load faclors .............................. ... ..... ............ Pl. I ChA pll
malerial coefficient ... ... ....... ... ... ... ................ Pt.1 ChA p 14
Floatout.. .......................... ............................... Pt.2Ch.l ·plS
air cushion system ... .... ... ... ... ........ ....... ........ Pl.2 Ch.l P 16
clearances .................................................... Pt.2 Ch.l pl6
Iloat oul site ................................................ Pl.2 Ch.l pl6
loads ................................................ ........... Pt.2 Ch.1 piS
monitoring ................. .................................. Pl.2 Ch. 1 pl7
mooring ..... .................................................. Pl.2 Ch.1 pl6
planning. ..... ....... . ... ... ............. ......... .... ........ Pt.2 Ch.l piS
Friction effects ................................................. Pt.l Ch.3 p13
friction coefficients ........................................ Pt.2 Ch.! p8
skidding ... ... ........ ........... ...... .............. .. ......... Pl2 Ch.l p8
certificalion noles ........................................... Pt.O Ch.! p7
classificalion notes ......................................... Pl.O Ch.! p6
cross references ...................... " ....... ............... PtO Ch.l p5
defmitions ...................................................... Pi.O Ch.! p6
guidance noles .. ................... ...... ..................... Pl'O Ch.1 p6
guidelines .............................................. ........ Pl.O Ch.! p6
numbering ...................................................... Pl.O Ch.1 pS
reprints ................................................ .......... Pt.O Ch.1 p6
revisions ...................................................... :. Pt.O Ch.l pS
structure of the Standard ................................ Pl.O Ch.l pS
symbols .......................................................... Pt.O Ch.l p6
table of contents ................. ............................ Pt.O Ch.l p6
Inspection
.
lift points ........................................ .... ......... Pl.2 Ch.S P 17
non destructive examinalion ......................... Pl.l Ch.4 pIS
shackles ....................................................... Pl.2 Ch.5 piS
slings ...................... ..................................... Pt.2 Ch.S P 14
through thickness quality .............................. Pl.! Ch.4 piS
-L-
-GGrillage and scafaslening
load oul... .................................................... Pl.2 Ch.l pl4
purpose ............. ............................................ PL2 Ch.2 p6
set down procedure ............... .................... ... Pt.2 Ch. l p13
Grouting ........................................................... Pl.2 Ch.4 pl8
equipment ...................... ............................. Pl.2 Ch.4 P 17
operational criteria ...................................... Pt.2 ChA P 18
Guiding systems
design requirements .................. ................... Pl. I Ch.2 p22
loads ...... ' ..... .... .... ............. ........... ... ..... ....... Pt. 1 Ch.2 p22
posilioning line requirements .. ..................... Pt.l Ch.2 p23
strength .............................. ... ...................... Pt.l Ch.2 p23
)
-H-
Lawtch
accidentaillooding ....................... .... .... .......... Pl.2 Ch.4 p9
anti self-lawtch devices .................................. Pl.2 ChA p9
barge positioning .......... ................. ............... Pl.2 Ch.4 pll
buoyancy tank attachments ............................. Pt.2 Ch.4 p9
buoyancy tank testing .......... .......... ............... Pl.2 Ch.4 pll
buoyancy tanks ............................................... Pl.2 Ch.4 p9
cutting facilities ........... ..... ............... ............ Pl.2 Ch.4 P 10
friction ........................... ...........•.................. Pl.2 Ch.4 plO
genera!... ..................... ......... ...................... .... Pl.2 Ch.4 p8
launch initiation ...... ....... .. ................. ............. Pl.2 ChA p8
launch syslems ........................................ ..... Pt.2 CbA p 10
loads and loadenses ........................................ Pl.2 ChA p8
monitoring ............ ....................................... Pl.2 ChA pll
object freeboard ............................................. Pl.2 ChA p9
object stiength ........ ................................... ..... Pl.2 ChA p9
DET NORSKE VERITAS
)
January 1996
Rules for Marine Operations
Page 18of22
Pt.O Ch.l User Infonnation Amendments and Indexes
preparations for launch ..... ... ..... ........... ....... . Pt.2 ChA P II
rubber diaphragms ....... ........................ .......... Pt.2 ChA p9
rubber diaphragms testing........................... . Pl2 Ch.4 pll
seabed clearance......... ..... ... .. ................ ......... Pl2 Cb.4 p9
slamming loads.......... ..... ...... ........... ........ ...... Pl2 Ch.4 p9
sliding surfaces.... ........ ...... ........ ........ ..... ..... Pt.2 ChA pi 0
spare buoyancy .................. ........... .............. ... Pl2 Ch.4 p9
system inspection. ..... ......... .......... ... ..... ..... .. Pl2 Ch.4 P 10
Launch barge
ballasting system ............. ' ... ..... ........... ........ Pl2 Ch.4 P 10
general ... ........ ..... ... ... ........ ......... ..... ... ...... ..... Pl2 Ch.4 p9
stability .. : ....... ..... .......................................... Pl2 Ch.4 p9
structural strength .... ...... ................................ Pt.2 Ch.4 p9
Launching
launch trajectory analysis ........................ ....... Pt.2 Ch.4 p8
Lift ofL.... ............... ........ ............ .... ............. .... Pt.2 Ch.1 P 18
ballast back up ........ ... ... ........ ... ... ..... ...... .... . Pt.2 Cb.1 p20
ballast capacity ...... .................. .................... Pt.2 Ch.1 p20
ballast contral centre ..... ... ...... ......... ..... ....... Pt.2 Ch.1 p20
ballast system.. ..... . ...... ... .... ........ ..... ...... ...... Pt.2 Ch.! p20
barge supports ....... .... ... .... ........ ........... ........ Pt.2 Ch.1 P19
clearances .................................................... Pl2 Ch.1 p22
construction supports. ... .. ............... ..... ... ...... Pt.2 Ch.1 P 19
lift off class ...... .. .... ... . ..... ...... ......... ......... .... Pt.2 Cb.1 P18
loads ................... .. .... ... ................ ... ............ Pl2 Ch.1 pl8
minimum freeboard ........ ... ...... ..... . ...... ........ Pt.2 Ch.! p21
monitoring ................................................... Pt.2 Ch.1 p22
mooring .............................. ......................... Pt.2 Ch.1 p21
planning .... ...... .... ....... ....... ...... ......... ... ........ Pt.2 Cb.1 P18
positioning systems ...................... ...... ..... ..... Pt.2 Ch.1 p21
shimming ................. .. ..... .......... .......... ..... ... Pt.2 Ch.1 P19
stability alloat..... ... .... .................. ... ............ Pt.2 Ch.1 p21
vessels................. .............. ..... . ....... ............. Pt.2 Ch.1 p21
Lift points
design considerations .................. ................. Pl2 Ch.S pl6
f.brication ........... ................. ................. ...... Pt.2 Ch.S pl7
inspection ........................................ ............ Pt.2 Ch.S pl7
materials ............... ........... ... ....... .. .... .. ......... Pt.2 Ch.5 P 17
revalidstion ............ ......... ........ ..... . ....... ....... Pt.2 Ch.5 P 17
Lifting
bumpers and guides ....... ...... ....... ... .............. Pt.2 Ch.S pl7
clearances .................................. ...... ............ Pt.2 Ch.S pl8
crane vessel... .. .... ................... ..................... Pl2 Ch.S pl8
cutting of seafastening........... ........ .............. Pt.2 Ch.5 P 19
double slings .............................................. ... Pl2 Ch.S p9
dynamic loads ...................... .......... ..... ........... Pt.2 Cb.5 p7
global skew load factor.. ....... ......................... Pt.2 Cb.S p8
lay down arrangements ... ... .......... .... ... ...... ... Pt.2 Ch.S P17
lift off conditions .................................... ..... Pt.2 Ch.S pl9
lifted objeet... ................ ................ .............. Pt.2 Ch.S pl6
load cases .................... .... ....... ·.· ········ ....... ·.. Pt.2 Ch.S plO
load factors .... .............................................. Pt.2 Ch.S pl6
monitoring. ..... ..... . ... ..... ..... ............. ........ .... . Pt.2 Ch.5 p 19
object weight... ............................. ......... ........ Pt.2 Ch.S p7
planning ...................... ... . ......... ..... ..... .... ....... Pt.2 Ch.S p6
seafastening and grill.ge .............................. Pt.2 Ch.S pl7
skew loads .................... ......... ........................ Pl2 Ch.S p8
special loads ..................... ... .................... ...... Pt.2 Ch.S p7
structural design .. .. .................. .... ............. ... Pt.2 Ch.5 pl6
weight of rigging ....... ................. ...... ...... .... ... Pl2 Ch.S p7
Lifting equipment
design considerations ................................... Pt.2 Ch.5 pl6
nomin. 1 safety factors ............. ..... ................ Pl2 Ch.S pl2
sling MEL.. .................... ................... ........... Pt.2 Ch.S p12
Load analysis ..... , ............ .. ... ............................. Pt. I Ch.3 p13
dynamic effects ............................................ Pt.l Ch.3 P 13
friction effects ....................................... ....... Pll Ch.3 P 13
model testing ............. ................................... Pli Ch.3 pl4
non· tinear effects .... ...................................... Pt.! Ch.3 pl3
sensitivity studies ......................................... Pt.! Ch.3 pl3
tolerances ..................................................... Pt. I Ch.3 p 14
Load cases
lifting .......................... ................................. Pl 2 Ch.5 plO
yard lifts.................................................. ..... Pl2 Ch.S p20
Load categories .............. .................... ............... Pt.l Ch.3 pl2
accidental loads ............................................ Pt.1 Ch.3 pl2
defonnation loads ............................. ............ Pt. I Ch.3 pl2
environmental loads ........ ................... .......... Ptl Ch.3 P12
live loads ..................................................... Pt.1 Ch.3 pl2
permanent loads ........................................... Pli Ch.3 pl2
Load combinations
motion and wind .......................... .. .. .. ............ Pl) Ch.4 p7
restruint and inertia loads ................ ............... Pt.1 Ch.4 p7
swell and irregular waves .............. ................. Pt.1 Ch.4 p7
Load factors
fatigue limit state .......................... ............... Pt.1 Ch.4 pll
progressive limit state ..................... ............. Pt.! Ch.4 P II
serviceability limit state ............................... Ptl ChA pl2
ultimate limit state ........................ ..... .......... Ptl Ch.4 pll
Load in .................. ...... ................................ ...... Pl2 Ch.1 P 14
Load ouL. ......................................... .. .............. .. Pl2 Ch.1 p7
ballast capacity .................... ......................... Pt.2 Ch.1 pi I
barge ballast system ............................ ......... Pl2 eh.1 p II
griIl.ge and seafastening .............................. Pt.2 Ch.1 P 14
load cases ................................................ ....... Pt.2 Ch.1 p9
load out class ................................................. Pt.2 Ch.1 p7
loads .................. ...:.. ...................................... Pl2 Ch.! p7
minimum freeboard ........ .............................. Pl2 Ch.1 p13
monitoring .......... ......................................... Pl2 Ch.! P 14
mnoring ........................................................ Pt.2 Ch.! p 12
planning .... ................ ................ .. .... ............... Pt.2 eh.! p7
power supply ................................................ Pl2 Ch.1 p12
push/pull equipment... .............. ...................... Pt.2 Ch.! p9
quays ........................ .......... ................ ........... Pt.2 Ch.1 p9
set down procedure ...................................... Pt.2 eh.! p!3
site ................................................... .. .......... Pt.2 Ch. 1 p!3
site move.......... ................................... ........... Pt.2 Ch.! p7
skidding equipment... ................................... Pl2 Ch.! plO
skidding loads .... ............................................ Pl2 Ch.! p8
soil ................................................. ................ Pt.2 Ch.! p9
stability afloat ................................ .............. Pt.2 eh.1 p13
testing .......... ................................................ Pt.2 eh.1 p!2
tmilers ......................................................... Pt.2 eh.! plO
underkeel clearance .... .................................. Pt.2 eh.! p 13
vessel... ...... .................................................. Pt.2 eh.1 p 12
vessel documentation ...................... ............. Pt.2 eh.1 p 13
vessel!barge maintenance .............. ............... Pt.2 eh.! p!3
Load transfer operations
documentation .............. .. ........ ........................ Pt.2 eh.1 p6
operational aspects ......................................... Pl2 Ch.1 p6
planning ........................ .. ............ ...... ............. Pt.2 Ch.! pS
-MMaterial coefficients
fatigue limit state .......... ...... ......................... Pt.! eh.4 p 14
Dr:r NORSKE VERITAS
January 1996
Page 19 of 22
Rules for Marine Operations
Pt.O Ch.l User Information Amendments and Indexes
progressive limit state.................................. Pt.1 Ch.4 pl4
serviceability limit statc ............................... Pt.1 Ch.4 pl4
ultimate limit state .......... ............................ Pt.l Ch.4 p13
wire ropes ................................................... Pt. 1 ChA pl4
Materials
fabrication ................................................... Pt.l Ch.4 pl4
inspection and fabrication .categories............ Pt.1 Ch.4 P14
steel qualities ............................ ........... ....... Pt.l Ch.4 P14
Mating ............... ...... ......... .............. ............ ..... Pt.2 Ch.1 p23
ballast systems ................ ............................ Pt.2 Ch.1 p24
clearances.... .................. ...... ........................ Pt.2 Ch.1 p26
griUage ........................................................ Pt.2 Ch.1 p24
loads ........................................................... Pt.2 Ch.1 p23
mating site...................................... ............. Pt.2 Ch.1 p2S
monitoring ................................................... Pt.2 Ch.I p26
mooring........................................... ............ Pt.2 Ch.! p2S
planning ...... ................................................ Pt.2 Ch.1 p23
positioning systems............. ...... ...... .. ...... ..... Pt.2 Ch.I p2S
seafastening ................................................. Pt.2 Ch.1 p24
systems ........................................................ Pt.2 Ch.1 p24
Model testing ................................................... Pt.l Ch.3 pl4
structures....... ................. ...... ....................... Pt.I ChA P12
Mooring
.
construction alloat ....................................... Pt.2 Ch.1 p27
float ouL ..................................................... Pt.2 Ch.1 pl6
lift off........................... ............... ................ Pt.2 Ch.1 p21
load ouL ................................................ ,.... Pt.2 Ch.1 pl2
mating ........................... ............. ..... ............ Pt.2 Ch.1 p2S
Mooring systems
anchors ........................................................ Pt.l Ch.2 p22
equipment ................................................... Pt.! Ch.2 p2I
general ... ....................... ...... ........................ Pt.l Ch.2 p20
tine strength ....... ........... ...... .......... .............. Pt.1 Ch.2 p21
loads ........... ......................... ....................... Pt.1 Ch.2 p20
PLS condition .............................................. Pt.1 Ch.2 p21
submerged brackets ............ ...... ................... Pt.1 Ch.2 p21
synthetic fibre ropes .................................... Pt.1 Ch.2 p21
ULS condition ............................................. Pt. 1 Ch.2 p20
wire clamps.......... ............. ........... ............... Pt.1 Ch.2 p21
Motion analysis ....... .................. ........ ............... Pt.1 Ch.3 P14
RAO's·................................. ......................... Pt.1 Ch.3 piS
wave headings ............................................. Pt.1 Ch.3p1S
wave periods ............................................... Pt.1 Ch.3 piS
Multi barge transports ........................................ Pt.2 Ch.3 p7
ballasting system ........................................... Pt.2 Ch.3 p8
clearances ...................................................... Pt.2 Ch.3 p9
monitoring .................................................. ,.. Pt.2 Ch.3 p9
navigational equipment.. ................................ Pt.2 Ch.3 p8
operational aspects ........................................ Pt.2 Ch.3 p9
seafastening. ............. ............................. ........ Pt.2 Ch.3 p8
skew loads ..................................................... Pt.2 Ch.3 p7
structural design verification .......................... Pt.2 Ch.3 p7
support structures .......................................... Pt.2 Ch.3 p7
towing equipment... ....................................... Pt.2 Ch.3 p8
towing route survey ............................... ........ Pt.2 Ch.3 p9
towing vessels ........ ..... ..................... ............. Pt.2 Ch.3 p8
-NNon destructive examination ............................. Pt.l ChA pIS
Objectives of the Standard ................................... PlO Ch.1 p4
Offshore installation
hydrostatic loads ............................................ Pt.2 ChA p7
loads from soil ........................... .................... Pt.2 Ch.4 p7
positioning brackets .... ................................. Pl2 ChA P13
positioning loads ....................... ..................... Pt.2 Ch.4 p7
site survey ...................................................... Pt.2 Ch.4 pS
site survey extent ........................................... Pt.2 Ch.4 p6
Organisation
briefing ........................................................ Pt.! Ch.2 P 13
CV's ........................................... ................. Pt. I Ch.2p12
responsibilities ............................................. Pt.! Ch.2 pl2
shift plan ...................................................... Pt.1 Ch.2 pl2
-pPartial coefficient method
acceptance criteria ........................................ Pt.l ChA plO
design approach ........................................... Pt.1 Ch.4 P10
fatigue limit state ......................................... Pt.1 ChA P II
load factors ......................... ......................... Pt.1 ChA PII
progressive limit state .................................. Pt. 1 ChA pll
serviceability limit state ............................... Pt.1 Ch.4 pI2
ultimate limit state ....................................... Pt.I ChA P11
Piling
clearances ..................................... ...... ......... Pt.2 Ch.4 P17
followers ...................................................... Pt.2 Ch.4 P17
general ..................................... ................... . Pt.2 Ch.4 P 17
installation ................................................... Pt.2 Ch.4 P 17
pile upending ............................................... Pt.2 Ch.4 P17
self penetration ............................................ Pt.2 Ch.4 P17
sleeve guiding .............................................. Pt.2 Ch.4 pl7
splash 20ne .................................. ................. Pt.2 Ch.4 P17
Planning
contingency situations .................................... Pt.1 Ch.2 p7
contingency time .......................................... Pt.! Ch.2 P10
operation reference period ............................ Pt.1 Ch.2 P10
philosophy ...................................................... Pt.! Ch.2 p7
principles .................................................. ..... Pt.1 Ch.2 p7
sequence ........................................................ Pt. I Ch.2 p7
Positioning ........................................................ Pt.2 Ch.4 pl4
ballast systems ................................. ............ Pt.2 Ch.4 pIS
docking general ....................... ... .................. Pt.2 Ch.4 piS
guides and bumpers ...................................... Pt.2 Ch.4 piS
guiding structures ......................................... Pt.2 Ch.4 pI6
horizontal docking ............................... ......... Pt.2 Ch.4 p 16
loads and loadeases ...................................... Pt.2 ChA P14
monitoring ........................... Pt.2 Ch.4 p16. Pt.2 Ch.4 piS
mooring........................................................ Pt.2 ChA piS
onbottom stability ...... ................................... Pt.2 ChA pl4
operational ................................................... Pt.2 ChA pl6
seabed survey ............................................... Pt.2 ChA pl6
stability afloat .............................................. Pt.2 ChA P14
structural strength .............................. .......... Pt.2 ChA piS
vertical docking ......................................... ... Pt.2 ChA pl6
Probability levels ................................................ Pt.O Ch.I .p4
Progressive limit state
.
load factors .................................................. Pt.l ChA P II
material coelIicient.. ..................................... Pt.1 ChA P14
Pull in operations
loads ............................................................ Pt.2 Ch.6 P12
DET NORSKE VERITAS
Rules for Marine Operations
Pt.O Ch.1 User Infonnation Amendments and lndexes
January 1996
Page 20 of 22
pipelines ...................................................... Pt.2 Ch.6 pl8
-R-
)
Responsibilities ................................................ Pl.I Ch.2 pl2
emergency situations ................................... Pt.1 Ch.2 pl2
Restrain loads
horizontal .................................................... Pt.1 Ch.3 pl6
vertical...................... ...... .......... ... ... .... ........ Pt.1 Ch.3 P 17
Revalidation
lift points..................... .......... ...... ... ..... ........ Pt.2 Ch.5 P 17
shackles:...................................................... Pt.2 Ch.5 pl5
slings ........................................................... Pt.2 Ch.5 pl4
Risk assessment .............. ........... .................. ...... Pt.l Ch.l p8
Risk evaluation ................................................... Pt.l Ch.2 p9
ROV operntions
I.unching ..................................................... Pt.2 Ch.6 pl7
monitoring ................................................... Pt.2 Ch.6 pl7
plauning ..................................... ................. Pt.2 Ch.6 pl6
thrnsterrequirements ................................... Pt.2 Ch.6 pl6
-8-
)
Seafastening ......... ............. .... ... ... .......... ...... ... .... Pt.2 Ch.2 p6
installation .................................................... Pt.2 Ch.2 p7
multi barge transports .................................... Pt.2 Ch.3 p8
purpose ....................... ... .... ............. .............. Pt.2 Ch.2 p6
ship transports ............................................... Pt.2 Ch.3 p5
Self floating towing
design loads ................................................. Pt.2 Ch.3 P 10
operational aspects ...................................... Pt.2 Ch.3 pll
rubber diaphragms ....................................... Pt.2 Ch.3 pI 1
system and equipment .. ... ...... ... .............. ..... PL2 Ch.3 P11
Sensitivity studies ............................................. Pt.! Ch.3 p13
Serviceability limit state
lo.d factors .................................................. Pt.l ChA pl2
material coellicienL......... ... ... ............ ......... Pt.l ChA P 14
Sh.ckles
certificates ................................................... Pt.2 Ch.5 pl5
design consider.tions ................................... Pl.2 Ch.5 pl5
inspection .................................................... Pt.2 Ch.5 pl5
manuf.cturing ............................................. Pt.2 Ch.5 pl5
revalidation ................................................. Pt.2 Ch.5 pl5
safe working load .... .............. ...... ............ .... Pt.2 Ch.5 p 14
testing .....•................................................... Pt.2 Ch.5 pl5
Ship transports .......................................... ,........ Pt.2 Ch.3 p5
design loads................................................... Pt.2 Ch.3 p5
documentation ............................................... Pt.2 Ch.3 p5
inspC!Otions .... ............. ....... ............. ......... ...... Pt.2 Ch.3 p6
plauning ...................... ..... ..... ... .... ... ..... ... ... ... Pt.2 Ch.3 p5
seafastening .........•......................................... Pt.2 Ch.3 p5
structural design ............................................ Pt.2 Ch.3 p5
transport manuaL ......................................... Pt.2 Ch.3 p6
Site move ........................................................... Pt.2 Ch.1 p7
Skew loads
additional tile effects ................................... Pt.2 Ch.5 plO
double sling effects ........................................ Pt.2 Ch.5 p9
global effects ................................................. Pt.2 Ch.5 p8
sling tolerance effects .................................... Pt.2 Ch.5 p8
tilt effects ............................................ ·.·· ...... Pt.2 Ch.5 p9
yaw effects .................................................... Pt.2 Ch.5 p9
Skidding equipment....... .... .... ... ....... .... .... ...... ... Pt.2 Ch.1 P10
Slanuning loads .................................................. Pt.2 Ch.6 p9
Slings
bending effects ............................................. Pt.2 Ch.5 pl2
certificates ................................................... Pt.2 Ch.5 p13
f.brication .................................................... Pt.2 Ch.5 pl3
handling ....................................................... Pl.2 Ch.5 pl3
inspection............................... ...................... Pt.2 Ch.5 pl4
revalidation .................................................. Pt.2 Ch.5 pl4
splice effects ................................................ Pt.2 Ch.5 pl2
tolerances ..................................................... Pl2 Ch.5 p13
Snap lo.ds
lifting ........................................................... Pt.2 Ch.6 pll
subsea operations ......................................... Pt.2 Ch.6 p II
Soil ................................................................... Pt.2 Ch.6 P 13
bottom survey ................................................. Pl.2 Ch.6 p6
material factors ............................................ Pt.2 Ch.6 p13
stability calculations ..................................... Pt.2 Ch.6 pl3
Stability
barge damaged stability ................................ Pt.l Ch.2 pl6
barge intact stability ..................................... Pt.! Ch.2 P15
calcul.tions .................................................. Pt.1 Ch.2 p 14
damaged stability ......................................... Pt.! Ch.2 pl4
general requirements .................................... Pt.! Ch.2 P 14
inclining test... ..................... Pt.! Ch.2 P 17. Pt.! Ch.2 P 15
inclining test procedure ................................ Pll Ch.2 P 15
load ou!... ..................................................... Pt.1 Ch.2 pl7
other vessles .................................... ' ............ Pll Ch.2 P 18
self flo.ting structures .................................. Pt.! Ch.2 p 17
temporary closing elements .......................... Pt.! Ch.2 pl4
watertight integrity ....................................... Pt.! Ch.2 P15
Static lo.ds
characteristic weighl.. .................................. Pll Ch.3 pl6
Co? ~sition ............................................... Pt.l Ch.3 p16
weIghing ...................................................... Pll Ch.3 p16
weight estiroates .... :...................................... Pt.! Ch.3 pl6
Structural design
accidental cases .............................................. Pt.! Ch.4 p6
characteristic resistance ....................... __ ....... Pt 1 ChA pI3
compressed .ir ............................................... Pt.! ChA p6
details ............................................................ Pt.! ChA p6
existing structures .......................................... Pll Ch.4 p6
principles ....................................................... Pll ChA p6
regnlation codes and standards ....................... Pt.! ChA p4
resistance ..................................................... Pt.! ChA P 13
sensitivity an.lysis ......................................... Pt.1 ChA p7
testing ............•............................................. Pt.! Ch.4 pl2
Structural details
through thickness stresses .............................. Pt. I ChA p6
trapped water ................................................. Pt. I ChA p6
Subsea opeartions
wave headings ................................................ Pt.2 Ch.6 p8
Subsea operations
ADS systems ................................................ Pt.2 Ch.6 pl6
ballast systems ............................................. Pt.2 Ch.6 pl5
commissioning ............................................. Pt.2 Ch.6 pl5
contingency .................................................. Pl2 Ch.6 P 15
crane tip motion ............................................. Pt.2 Ch.6 p8
current force on ROV ................................... Pt.2 Ch.6 pl2
documentation ................................................ Pt.2 Ch.6 p5
dynamic positioning systems ........................ Pl.2 Ch.6 pl5
environmental loads ....................................... Pt.2 Ch.6 p6
guiding systems ............................................ Pt.2 Ch.6 pl6
hydrostatic loads ........... :................................ Pt.2 Ch.6 p6
loads .............................................................. Pt.2 Ch.6 p6
DET NORSKE VERITAS
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January 1996
Page 21 of 22
Rules for Marine Operations
Pt.O Ch.1 User Infonnation Amendments and Indexes
o!flead forces .............................................. Pt.2 Ch.6 pl2
operation manual... ........................................ Pt.2 Ch.6 pS
planning ........................................................ Pt.2 Ch.6 pS
procedures ................................................... Pt.2 Ch.6 pIS
pull in/down loads ....................................... Pt.2 Ch.6 pl2
pull out drainage .......................................... Pt.2 Ch.6 p13
pull out forces .............................................. Pt.2 Ch.6 p13
pull ou~ e!fect of filters ............................... Pt.2 Ch.6 pl4
ROV operations ........................................... Pt.2 Ch.6 pl6
snap loads ................................................... Pt.2 Ch.6 pI I
structural strength .......................................... Pt.2 Ch.6 p?
systems ..... , .................................................. Pt.2 Ch.6 pIS
vessel motion ................................................. Pt.2 Ch.6 p8
Systems
back up ................................ PU Ch.2 p19.
design requirements .....................................
test requirements .........................................
testing .........................................................
Pt.1
Ptl
PU
Pt.1
Ch.2 pl2
Ch.2 pl9
Ch.2 pl9
Ch.2 pl2
-TTesting
shackles ....................................................... Pt2 Ch.S pIS
structural strength ........................................ Pt.! ChA pl2
wave efficiency factors ................. _............... Pt.2 Ch.2 P 10
Towing line
accept criteria ............................................... Pt.2 Ch.2 P II
inspection ..................................................... Pt2 Ch.2 P II
MEL requirements ......................................... Pt.2 Ch.2 p8
Towing procedure ............................................. Pt.2 Ch.2 pl4
escort tug ..................................................... Pt.2 Ch.2 P 14
guard ship .................................................... Pt.2 Ch.2 pl4
Towing vessels
criteria for selection .. ........ .............. ,_ ........... Pt.2 Ch.2 P10
documentation .............................................. Pt.2 Ch.2 pll
inspection and testing ................................... Pt.2 Ch.2 P II
personnel bnmsfer... ...................................... Pt2 Ch.2 P 11
spare towing line .......................................... PI.2 Ch.2 pll
towing line ................................................... Pt2 Ch.2 P II
towing winch ................................................ Pt.2 Ch.2 p II
winch ........................................................... Pt2 Ch.2 P 10
Trailers ............................................................. Pt.2 Ch.1 pi 0
Transports
heavy lift carrier transports ........................... Pt.2 Ch.3 P 12
multi barge transports..................................... Pt.2 Ch.3 p?
ship transports ................................................ Pt.2 Ch.3 pS
-u-
Tie in operations
ROV recommendstions ................................ Pt.2 Ch.6 pI?
Towing
.
barge ballast condition ................................. Pt2 Ch.2 pl4
barge trim and draft ..................................... Pt.2 Ch.2 pl4
ceitified equipment...... ........ .... ... ............... .... Pt.2 Ch.2 p6
design loads........ ...... ...... .... ... ........ ......... ....... Pt.2 Ch.2 p6
documentation ............................................... Pt.2 Ch.2 pS
environmental conditions ............................... Pt.2 Ch.2 pS
fiber rope pennants... ......... ........................ .... Pl2 Ch.2 p9
internal seafastening .................................... Pt.2 Ch.2 p13
load cases. .......... .... ...... ... ... .... ..... ............ ...... Pt.2 Ch.2 p6
manual. ..... .......... ... .... .... ...... ..... ........ .... ........ Pt.2 Ch.2 pS
motion.......... ..... ... ... ....... ... ......... ..... ....... .... ... Pt.2 Ch.2 pS
planning ... ..... ........ ... ... ............................ ...... Pt.2 Ch.2 pS
ports of shelter. .............................................. Pt.2 Ch.2 pS
routing....... ....... ... ....... ....... ......... ... ......... ..... Pt.2 Ch.2 P 13
siroplified motion criteria... ...... ..... .......... ... ... Pt.2 Ch.2 pS
structural strength verification ....................... Pt.2 Ch.2 p6
towing clearances ...... ... ....... ....... ................. Pt.2 Ch.2 P 13
towing in narrow waters ... .... .... ..... ... ..... ...... Pt.2 Ch.2 P 14
towing manuaL ........................................ " Pt.2 Ch.2 P 13
towline attachements .................................: ... Pt.2 Ch.2 p9
tow-out couditions ....................................... Pt.2 Ch.2 p13
tow-out criteria ......... ........ .... ... ............. ....... Pt.2 Ch.2 P 13
unrestricted towing... ...... ... ....... ... ........ .... ...... Pt.2 Ch.2 pS
weather forecast ...... ..... ............. ... ............ ... Pt.2 Ch.2 P 13
weather routed towing ...... ...... ... ....... ...... .... ... Pt.2 Ch.2 pS
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Ultimate limit state
load factors .................................................. Pt I Ch.4 P II
material coefficients ..................................... Pt.1 ChA p 13
Units ................................................................... Pt.O Ch.1 p6
Unrestricted operations ..................................... Ptl Ch.2 plO
Upending operations ......................................... Pt2 ChA pl2
ballast system backup ................................... Pt.2 ChA pl3
ballast systems .....•....................................... Pt.2 ChA P 13
loads and loadeases ...................................... Pt2 ChA pl2
monitoriog ................................................... Pt.2 ChA .p13
seabed clearance .......................................... Pt.2 ChA P 12
spare buoyancy ............................................. Pt.2 ChA pl2
stability afloaL ........................................... Pt.2 ChA pl2
structural strength ........................................ Pt.2 ChA p 13
-vVerification
quality surveyor. ............................................. PU Ch.1 p9
third party verification .................................. Pt.1 Ch.1 pi 0
Vessel
condition .....................................................•
deck load chart .............................................
system description ........................................
Vessels
general requirements ....................................
load ouL. .....................................................
Pt.1 Ch.2 p20
Pt.! Ch.2 p20
Pt. I Ch.2 p20
Ptl Ch.2 pl9
Pt2 Ch.! pl2
Towing arrangement
bridle ............................................................
emergency towing arrangement... ...................
general ..........................................................
recovery arrangements... .................... ...... ......
Pt.2 Ch.2 p8
Pt.2 Ch.2 p9
Pt.2 Ch.2 p8
Pt.2 Ch.2 p8
Towing equipment
multi barge transports .................................... Pt.2 Ch.3 p8
self floating towing ...................................... Pt.2 Ch.3 plO
Towing force
)
barge interaction e!fects ............................... Pt.2 Ch.2 plO
open sea .. ..... ................................ ...... .... ..... Pt.2 Ch.2 P 10
-wWarrnnty scope
alternative methodes .................................... Pt.l Ch.1 plO
risk differentiated scope ................................. Pt.1 Ch.1 p8
Warranty Survey
risk evaluations .............................................. Pt.l Ch.2 p9
Warranty surveys
approval in priDeiple ...................................... Pt. I Ch.1 p9
approval work .............................................. Pt.l Ch.1 P 10
DEI" NORSKE VERITAS
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January 1996
Page 22 of22
Rules for Marine Operations
Pt.O Ch.1 User Wonnation Amendments and Indexes
attendance .... ....... ... ........... ... ........ ..... .......... Pt.l Ch.l P11
basic principles.... ......... ................. ....... ... ... ... Pt.I Ch.l pS
breach of warranty ................. Pt.l Ch.l pi!. Ptl Ch.I p6
certification of operators. .... ........... ... ..... ........ Pll Ch.l p9
docwnent review ........................ ,................ Ptl Ch.I pIO
duties of assured .......................................... Pt.I Ch.l pl2
duties ofinsurer. .......................................... Pll Ch.I pl2
duties of warranty surveyor .......................... Pt.! Ch.l pl2
inspection .................................................... Pt, I. Ch.l pi 1
issuance of declarations ............................... Pt.l Ch.l pI1
marine insurance ac!.................... .................. Pt. 1 Ch.l pS
marine operations.... ...... ...................... .......... Pt.l Ch.l pS
marine surveyors.. ...... ............ .......... ............. Pt. 1 Ch.I p4
needs and duties ............. : ............................ Pt.I Ch..! pI2
parts involved .............................................. Pt.l Ch.1 pIO
roles ...... ................ ...... .................. .......... ...... Pt.l Ch.l pS
site survey ................................................... Pt.! Ch.I pll
testing .................... ........ ........ ............ ......... Pt.l Ch.1 P II
third party verification ................................. Pt.l Ch.1 plO
tools .............................. ...... .......................... Pt.1 Ch.1 p8
warranty clause .............................................. Pt I Ch.1 p7
Wave drift forces
barges........ ...... ............ ............ .................... Pt.2 Ch.2 P 10
Waveheigbt
unrestricted operations ................................... Pt.1 Ch.3 p8
weather restricted operations.. ....................... Pt.I Ch.3 p8
Wave loads
design spectra method ...... .......... ................... Pt.l Ch.3 p9
design wave method ...................................... Pt.l Ch.3 p9
)
frrstorderwaveloads .................................. PtICh.3pI4
second order wave loads .............................. Pt.! Ch.3 pl4
slamming ............................. Pt.1 Ch.3 pIS. Pt.I Ch.3 pl4
swell ........................................................... Pt.1 Ch.3 pIS
water on deck .............................................. Ptl Ch.3 pIS
Weather forecast
acceptance criteria ....................................... Pt.1 Ch.2 pll
assessment ............ ...................................... Pt.1 Ch.2 P II
levels..... ............ .......................................... Pt.1 Ch.2 p II
procedure ............ .......... .............. ........ ........ Pt I Ch.2 P II
requirements.. .......................... ................... Pt.1 Ch.2 P II
Weather restricted operations ........................... Pt I Ch.2 pIO
operation vs, design criteria... ...................... Pt.I Ch.2 P10
Weigbing ......................................................... Ptl Ch.3 pl6
Weigbt ............................................................. Pt.I Ch.3 pl6
Wind loads ....................................................... Ptl Ch.3 pIS
Wind velocity
unrestricted operations ................................... Pt I Ch.3 p7
weather restricted operations ......................... Pt.1 Ch.3 p7
-yYard lifts ..........................................................
clearances ....................................................
crane allowable loads ..................................
erane documentation .................. ..................
cranes ..........................................................
general requirements ...................................
lifting equipment.. .......................................
lifting points ............ ........ ................ ............
loads ...........................................................
Pt.2 Cll.S p20
Pt.2 Ch.S p21
Pt.2 Ch.5 p21
Pt.2 Ch. S p21
Pt.2 Ch.S p21
Pt.2 Ch.S p20
Pt.2 Ch.S p21
PI.2 Ch.S p21
PI.2 Ch.S p20
DEf NORSKE VERITAS
n
RULES FOR
PLANNING AND EXECUTION OF
MARINE OPERATIONS
PART 1 : GENERAL REQUIREMENTS
()
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PART 1 CHAPTER 1
WARRANTY SURVEYS
JANUARY 1996
SECTIONS
,
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1. PRINCIPLES OF INSURANCE WARRANTY SURVEyS . ...... .. ...... ... ..... ...................... ... ... .... .......... 4
2. SCOPE OF INSURANCE WARRANTY SURVEyS . .. ....... .. . ...... .. .. .... .. .......... . ......... ........ ... .. ... ........ 7
3. PROCEDURES FOR INSURANCE WARRANTY SURVEyS ................. ........ .... ........ . ..... . .. .. ..... ....... 10
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DET NORSKE VERITAS
Veritasveien 1, N-1322 H""ik, Norway Tel.: +4767579900, Fax.: +47675799 11
'.•
CHANGES IN THE RULES
This is the first issue of the Rules for Planning and
Execution of Marine Operations, decided by the Board
of net Norske Veritas Classification AlS as of December
1995. These Rules supersedes the June 1985, Standard
for Insurance Warranty Surveys in Marine Operations.
These Rules come into force on 1st of January 1996.
This cbapter is valid until superseded by a revised
chapter. Supplements to this chapter will not be issued
except for minor amendments and an updated list of
corrections presented in the introduction booklet.
Users are advised to check tbe systematic index in the
introduction booklet to ensure tbat tbat the cbapter is
current.
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)
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€I Del Norlike Verita6
Computer Typesetting by Det Non;ke Verita&.
Printed in NOrw8Y by the Det Nonke Veritas January 1996
1.96.600
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Rules for Marine Operations
Pt.1 Ch.1 Warranty Surveys
January 1996
Page 3 orll
CONTENTS
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1.
PRINCIPLES OF INSURANCE WARRANTY
SURVEYS ....................... ...•.....•.•..•. •.... 4
3.
PROCEDURES FOR INSURANCE
WARRANTY SURVEyS .•.•..•.••..•.....•••••. 10
l.l
INTRODUCTION ........•...... .... ......... ..... . . 4
1.1.1 Objectives ..... . .............. . .. . . ... .......... 4
1.1.2 Application ..... . ..... . ........................ 4
3.1
ENGAGEMENT OF THE WARRANTY
SURVEYOR .. ....... : . ... . . . .... .. ...... . .. .... . .... 1O
3 . 1.1 Warranty contract partners . . .. . ......... . .. 10
1.2
BASIC DEFINITIONS . .. . ...... ... .......... . ..... 4
1.2. 1 Parties involved .... . .... .... .................. 4
1.2.2 Marine surveyors .. . ............ ... ..... . .. ... 4
1.2.3 Marine operations . .. . .. ... . ... . .... .... . ..... 5
3.2
BASIS FOR WORK ... .. . ......... . .... ... ...... . .. 1O
3.2. 1 Main or alternative methods ............... 10
3.2.2 Assumptions ..... . ..... ...... . ... . . . ........ . . l0
3.3
1.3
MARINE INSURANCE ACT .... .. ... ... . ........ 5 .
1.3.1 Terms of reference .... .. ..... . .......... .. ... 5
1.4
PURPOSE OF INSURANCE WARRANTY
SURVEYS .. ... . . . .... ................................ 5
1.4.1 Basic principles ................ ... .. .. ... . .... 5
1:4.2 The role oftbe warranty surveyor .... . .... 5
APPROVAL WORK ... . .. . . .. ..... ........... . .. . . I0
3.3.1 Documentation ..... ... . ... ................. . . 10
3.3.2 Document review .......... . ................. 10
3.3 .3 lndependent computer analysis ........... . 10
3.3.4 Third party verification .... .. ............. . . 10
3.4
PREPARATION FOR OPERATIONS ... . . . ... . 10
3.4.1 Site surveys . .. ............ ......... ..... ...... IO
3.4.2 Functional testing ........ ....... . .. ... . ... ... 11
3.4.3 Vessels and equipment certification
control ........ ...... . .. . . ...... ..... ................ . . 11
3.4.4 Issuance of marine operation declaratioDs11
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1.5
MARINE OPERATION DECLARATIONS .. .. 5
1.5.1 Issuance of declarations ...... . ........ .. ... .. 5
1.5.2 Maintenaoce of declarations ...... .. .. .. .... 6
1.6
BREACH OF WARRANTY ....... .... .... .... .. .. 6
1. 6.1 Deviation from approved procedures .. .. .. 6
3.5
ATTENDANCE DURING OPERATION . . .... 11
3.5.1 Surveillaoce of operation . . . .... . ........... 11
3.5.2 Breach of warraoty . .. .. .... . ..... ........... 11
2.
SCOPE OF INSURANCE WARRANTY
SURVEYS ............................................ 7
3.6
2. 1
WARRANTY CLAUSE .... .. .. .................... 7
2. 1.1 Adsptation to risk level.. .. .... ....... .. .... . 7
NEEDS AND DUTIES OF PARTIES
INVOLVED .. ..... . ....... . .......... . ...... . ....... 11
3.6. 1 Difference of opinion . .... .... ...... . ..... . . 11
3.6.2 Duties of insurer .. . . . .. .. ....... . ...... .. . .... 12
3.6.3 Duties of assured . .... ........ . .. .. ...... . ... 12
3.6.4 Duties of warranty surveyor ............... 12
2.2
WARRANTY SURVEYOR TOOLS ............. 8
2.2.1 Type of tools available .. .... .... .. .... .... ... 8
2.3
WARRANTY LEVEL ...... ............ .... ........ 8
2.3.1 Risk differentiated scope .. .. ...... .. ....... . 8
2.4
RISK ASSESSMENT ............................ .. . 8
2.4.1 Requirements from authorities .. ............ 8
2.4.2 Simplified risk evaluation .. .. .... .. .. ... ... . 8
2.5
REDUCED SCOPE OF WARRANTY .... .... .. 9
2.5.1 Approval in principle .. ................... .. . 9
2.6
EXTENDED SCOPE OF WARRANTY .... .. .. 9
2.6.1 Quality surveyor .............. .. .... .. .... .... 9
2.6.2 Marine advisory services ...... .. ...... .. .... 9
Table List
Table 2.1 - Warranty Levels .............................. 8
Figure List
Figure 2.1 -Classification of risk as a function of
probability of hazards and consequences. 7
DET NORSKE VERIrAS
January 1996
Page 4 of 12
Rules for Marine Operations
Pt.l Ch.l Warranty Surveys
1. PRINCIPLES OF INSURANCE WARRANTY SURVEYS
1.1 INTRODUCTION
1.2 BASIC DEFINITIONS
1.1.1 Objectives
1.2.1 Parties involved
1.1.1.1 Pt. 1 Ch.1, Warraoty Surveys, describes how
these Rules shall be applied for Insurance Warraoty
Surveys in Marine Operations.
1.2.1.1 The different parties involved are:
1.1.1.2 The purpose of Warranty Surveys is to ensure
that Marine Operations are performed within defined
risk levels. The risk levels, as specified in Pl. 0 Ch.1
Sec. 1.2.2, should be tolerable to marine insurance and
also to the industry, as well as to the national and
international Regulatory Bodies.
)
1.1.2 Application
1.1.2.1 These Rules describes the formal and teehnical
requirements which DNV considers necessary for proper
planning and safe execution of marine operp,tions.
1.1.2.2 The Rules applies to Warranty Surveys of all
structures, opjects, vessels and equipment, systems and
procedures involved in marine operations. It covers the
range from simple coastal transportations to complex
offshore installations. It also applies to evaluation of the
selected mode of marine operations in relation to Gargo
or object suitability, e.g. with respect to internal
strength or water integrity.
1.1.2.3 The requirements given in this chapter shall
form the basis for Insurance Warranty Surveys in marine
operations but the Rules will also be used for other types
of work. e.g. oil companies verification requirements,
see Pt. 0 Ch.1 Sec. 1. 2.1 . .
Operator/Company: the party representing the
owner(s).
Contractors: the parties performing the actoaJ work.
Assured: the party who has obtained an insurance cover
for the marine operation and who engages the Warranty
Surveyor in·order to ensure that the terms of the
warranty as laid down in his Insurance Policy are
complied with. This may be the Operator/Company or
the Contractor.
o
Insurer: the party who is providing insurance cover for
the marine operation.
VMO: Veritas Marine Operations, a product offered by
DNV. The product responsibility is assigned to a
specific DNV organisational unit.
Warranty surveyor: the independent third party ensuring
that the terms of the Marine Insurance Warraoty Clause
is complied with.
1.2.2 Marine surveyors
1.2.2.1 The Marine Surveyor is the one who carries out
the survey, which includes examination and evaluation
of the operation and conditions ascertaining acceptable
~
risks.
1.2.2.2 The marine surveyors may have different tasks
and act in different roles according to the needs of the
parties involved. The three typical roles are:
Warranty Surveyor,
Quality Surveyor or Verification Body
Marine Advisor.
1.2.2.3 Warraoty Surveyor is defined above and the
roles as Quality Surveyor and Marine Advisor are
described in 2.6.
)
DEI" NORSICE VERITAS
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Rules for Marine Operations
January 1996
() ~Pt~.~l~C~h~.~l~VV~ar~ran~~~s~~~ey~s~______________________________________________~P~ag~e~5~of~12
1.2.3 Marine operations
1.2.3.1 Marine Operations are in general all activities
pertaining to the sea, but in this context limited
according to the definition in Pr.D CiI.l Sec. 1.1.1. This
covers the temporary phases in connection with load
transfer, transportation and/or securing of units at sea,
1.3.1.2 The above terms of reference are particularly
relevant for the London Insurance market, but are
regulated according to law in the different countries.
Thus, in Norway it is necessary to be able to show a
direct causal connection between the accident and the
condition resUlting in breach of warranty in order to
discharge the insurer from liability.
1.2.3.2 Typical marine operations are;
load out, float out, float on/off,
towing, self propelled carrier transports,
launching, upending, position,ing,
setting, piling, grouting,
lifting, lift off, mating,
transit and positioning of semi submersibles or
jack-up rigs, and
subsea operations, special marine operations.
)
1.3 MARINE INSURANCE ACT
1.4 PURPOSE OF INSURANCE VVARRANTY
SURVEYS
1.4.1 Basic principles
1.4.1.1 By adherence to a recognised .Standard the
Insurer will achieve reductions
in insurance claims, but
it is important that the Insurer is aware of the fact that a
Warranty Surveyor can only reduce not elimiDate risk.
1.4.L2 The scope of work of an insurance warranty
survey is to some extent subject to agree.~ent betw~n
1.3.1 Tenns of reference
1.3.1.1 The term Marine Insurance Warran~ as used in
marine insurance is based on the UK Marine lnsurance
Act 1906 and is according to "Dictionary of Marine
Insurance TeI11lB and Clauses" by R.H. Brown 1989
defined as:
the parties involved. However, the warranty conditions
as defined in the insurance documents and disclosed to
the Warranty Surveyor shall be complied with.
1.4.2 The role of the warran~ s~eyor
1.4.2,1 The Warranty Surveyor will require;
A marine insurance warranty is a promissory
warranty by which the assured undertakes that
some partiCUlar thing shall or shall not be done,
or that some condition shall be fulfilled, or
whereby he affirms or negatives the existence
of a particular state of facts.
that satisfactory plans and procedures according
to these Rules are prepared for thi: operation,
that satisfactory preparations are carried out to
the extent and in the manner approved for the
operation,
The assured must comply literally with the
teI11lB of a warranty. Compliance in spirit is not
acceptable. If the assured fails to comply with
that the marine operations are performed in
accordance with the approved procedures, and
that the work is carried out in compliance with
these Rules.
the terms of the warranty, the insurer is
discharged from all liability uoder the policy as
from the date of breach of warranty, but
without prejudice to insured losses occurring
prior to such date.
1.5 MARINE OPERATION DEC~ARATIONS
n
A warranty may be "express or "implied". An
express warranty is set out in the policy
conditions. An implied warranty does not
appear in the policy, but is implied to be
therein by law.
1.5.1 Issuance of declarations
1.5.1.1 When the required documentation has been
approved, the prevailing conditions have been fouod
acceptable, and all surveys completed to the Warranty
Surveyor's satisfaction, a Marine Operation Declaration
will be issued. The general requirements to obtain a
Declaration are specified in Pr.1 Ch.2 Sec. 2.4.1.
DET NORSKE VERITAS
January 1996
Rules for Marine Operations
Pt.1 Ch.1 Warranty Surveys
Page 6 ofll
1.5.1.2 A Warranty Surveyor is not responsible for the
operation and can not by any efforts inspect'quality into
it, but he shall reject to issue a Marine Operation
Declaration if he is not satisfied with the planning and
preparations fot the operation.
1.5.2 Maintenance of declarations
1.5.2.1 It is the responsibility of the Assured to ensure
that conditions given in the Marine Operation
Declaration are complied with. The operation shalI be
carried out with a safety level as specified in 2.1.1 .
1.6 BREACH OF WARRANTY
)
1.6.1 Deviation from approved PrOC<!dures
1.6.1.1 It is the duty of the Warranty· Surveyor to
inform the AsSured when for any reason there is a breach
of warranty . . Such a situation may arise if and when
there is a deviation from ,the approved procedure and the
deviation is not approved beforehand by the Warranty
Surveyor.
o
1.6.1.2 When a breach of warranty situation bas
occurred, the Warranty Surveyor shall immediately
notii'y tbe Assured in writing, informing him of breacb
of warranty and the reasons for this. The Marine
Operation Decl":,,,tion becomes at the same tiine invalid.
1.6.1.3 If the condition'leading to tbe breach of
warranty does no longer exist, the Warranty Surveyor
may revalidate the Marine Operation Declaration. If
there are reasons to believe that damages have occurred
during the time of the breach of warranty, a reservation
to this effect will be slated on the Declaration.
1.6.1.4 The Warranty Surveyor wilI act according to
tbe Terms of Reference as' defined in 1. 3.1 above. It is
only the implications of a breach of warranty which may
be differe"t due to p,Dssible differences in the insurance
laws oftbe different countries as indicated in 1.3.1.
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DET NORSKE VERITAS
i)
Rules for Marine Operations
Pt.1 Ch.1 Warranty Surveys
January 1996
Page 7 of 12
2. SCOPE OF INSURANCE WARRANTY SURVEYS
Figure 2.1 - Classification of risk as a function of
of
2.1 WARRANTY CLAUSE
2.1.1 Adaptation to risk level
2.1.1.1 The risk level is depending on the probability
of bazards and the consequences. For marine operations
the consequences are mainly related to the following
three areas; damages or loss of units and objects
involved, delay or production down time and personnel
injuries or fatalities.
)
2.1.1.2 The different parties involved may bave
different focus on the possible consequences. The marine
insurance interests are
in most cases to avoid claims due
to damages to the insured objects. These Rules establish
a tolerable risk level in particular related to such needs.
\
~YPlcal Manne - \
Operations
2.1.1.3 An Insurance Warranty Clause sball be adapted
to the risk ]ev~l of the marine operation under
considerati90. 1bis requires a dialogue between the
insurer, Assured and the Warranty Surveyor.
2.1.1.4 The matrix presented in Figure 2.1 illustrates
the combinations of consequence and initial probability
of failure which results in "intolerable risk" and
" tolerable risk" . The border area between intole",ble
and tolerable risk is denoted" ALARP - As Low As
Reasonably Practicable" 004 therefore requires actions to
be laken in order to be tolerable.
2.1.1.5 The purpose of insurance warranty is to ensure
that no operations are approved to be carried out with
"intolerable risk'~ and that &.II necessary actions ar~ taken
<.
for operational bazards in tbe ALARP area. For this
purpose 4 different warranty scope levels denoted from
WO to W3 are indicated. These are described in 2.3. 1
below.
2.1.1.6 The definitions of the consequences are;
Minor: An event that causes local damage to the unitandlor light personnel injuries.
Severe : An event that causes large damage to unit
and/or serious personnel injuries.
Fatal: An event threatening the integrity of tbe unit
and/or cause fatalities .
CataStrophic :An event tbat causes loss of unit andlor a
number of fatalities.
Disastrous: An event tbat causes loss of unit andlor a
very large number of fatalities.
2.1.1.7 . .in practice it may be difficult to define
probability levels directly, and therefore robustness or
vulnerability aspects such as complexity of the operation
on otie side and safety margins or redundancy on the .
other, may give simple and more relevant criteria for
selection of tbe Warranty Level.
Guidance Note
The expressed warranties may for instance be formulated as:
-Warranted Del Norske Verltas , Marine Operations shall be the
Surveyors to approve the lug, tow, towage, loading and stowage
arrangements for an tows according to warranty level W1
(alternatively W2 or W3)".
DET NORSKE VERITAS
January 1996
)
Rules for Marine Operations
Pt.t Ch.l Warranty Surveys
PageS of 12
2.2 WARRANTY SURVEYOR TOOLS
Table 2.1- Warranty Levels
~~~e?~ r w'\'A~~b¥~Y~ ) .. · .li~,);.,'<:;;:;
2.2.1 Type of tools available
Simple
2.2.1.1 The typical work methods or tools to be applied
by the Warranty Surveyor are:
Verification of established Design Criteria
Document Review and verification of
Design calculations and drawings
Operational manuals and procedures
Site Surveys and approval
Surveys during construction
Commissioning
Surveys of vessels and equipment
Preparations prior to operation
Verification of established. Operational
Umilations
Weather criteria
Other conditions for declaration
Attendance during operation
SurveiIIance according to approved
procedure
WO
:~~ti~~S
ed
i No Warranty
i Basic quality level for marine
d
1 operations, no Warranty Declaration
~ .....~.~ . ~~.~~.......l............ f...~~9.~1!'~9..~.¥..~~~.!n~~.~n.'?~.:....................... _
Well
controlled
simple
operations or
high
redundancy
;.~ WI
i.
l
i Warranty Declaration to be Issued
1
i
i
1
Complex or
weather
sensitive
operations
i either only based on evaluations of
l ! documentatIon (e.g. for MoU location
i
! approval), or ~mly accordIng to surveys
1
i on sHe (e.g. lashing of ship cargo).
1
.-.....................
Limited Scope of Warranty
1The most relevant alternative to be
j selected by the Warranty Surveyor.
! The Declaration should specify
i conditions for operation as found
!.............i!....necessary
(e.g. weather restrictions).
- .---........- .........- ......... .....................- ..
-.-.~
~.-
1 W2 1 Standard Scope of Warranty
~
i
i
i
i As W1, but including both evaluation
f of design documentation and
! operational procedures as basis for
i Verification surveys prior to the
. . . . . . . . . _. ._. . .~. . ._. . . !..'?£.~~.!i.~_(':.:g:.~j~.9.1~.P..<!r.9.~.!!?~n91:........
2.2.1.2 Design criteria andlor operational limitations
wiII always have to be established and the other main
Complex and 1 W3
sensitive
operations
elements are Document Review, Site Surveys and
Attendance during operations. These three elements are
referred to in order to define the warranty level.
Dependent on the risk level of the marine operations
only some or all the tools may be necessary to apply.
! Full Scope of Warranty
j
1
1 As W2, but Including surveillance of
i the operation (e.g. mating operation).
!
i
2.4 RISK ASSESSMENT
2.4.1 Requirements from authorities
2.3 WARRANTY LEVEL
2.3.1 Risk differentiated scope
2.3.1.1 The requirements to warranty level as a
function of initial risk shaIl be as presented in the Table
2.1 below.
2.3.1.2 The Warranty Surveyor shaIl evaluate the
warranty level selected by the Insurer during his work
and if necessary adjust the level and inform the Assured.
who shall inform the Insurer. The aim shaIl be that all
operations are carried out with "tolerable risk" as
specified in 2. 1.1.
2.4.1.1 Some Regulatory Bodies require risk
evaluations to be carried out in connection with all
offshore activities. In principle a Risk Analysis or
Formal Safety Assessment may be worked out. but in
practice there is a lack of statistical data for marine
operations and therefore some simplified approaches are
required.
2.4.1.2 Risk Analysis may be relevant for comparisons
of alternative marine operations. The probability of
failure may also be calculated for structural strength in
relation to e.g. the wave and wind loads in order to
document a specific safety level.
2.4.2 Simplified risk evaluation
2.4.2.1 Based on experience some Reference Cases
(RC) with a defined risk level may be established for
typical marine operations. For each new operation a
Rapid Risk Ranking (RRR) checklist should be used in
order to assess the risk level relative to the most relevant
Re.
DET NORSKE VERITAS
o
Rules for Marine Operations
Pt.! Ch.! Warranty Surveys
January 1996
Page 9 of 12
)
2.4.2.2 In Table 2.1 some examples are given with
respect to typical Reference Cases for each warranty
level. The RC of a single barge towing is for example
specified under W2. However, a single barge towing
may weU end up as either WI or W3 depending on the
RRR checklist evaluation of the particular case.
2.4.2.3 For complex or novel operations it is
recommended to carry out a HAZOP (HAZard and
Operability) analysis as a documentation of the most
relevant risk elements and the recommended actions to
be taken, see Pc.1.Ci•. 2 Sec 2.3.2. It is recommended
that the Warranty Surveyor participate in the HAZOP
team.
I'
)
2.6 EXTENDED SCOPE OF WARRANTY
2.6.1 Quality surveyor
2.6.l.1 The Operator/contractors may have additional
needs for marine services andlor verification over and
above what normally is covered in the scope of work for
Warranty Surveys. To cover such needs a role as Marine
Quality Surveyor or Verification Body is introduced.
2.6.l.2 The Quality Surveyor is an independent
facilitator in a marine operation project who is appointed
to ensure, through evaluations, veri fications and
inspections, that the terms of quality as selected by the
Operator or Contractors ilnd specified in the relevant
design, fabrication or operational contracts are complied
with. The combination of Warranty & Quality Surveys is
2.5 REDUCED SCOPE OF WARRANTY
expected to improve both quality and cost efficiency of
the control work and the operations.
2.5.1 Approval in principle
2.5.1.1 Marin" operations are normally approved by
the Warranty Surveyor case by case. However, in
principle these Rules opens up for approval based on
quality system and procedure certification with
documentation of skill. Due to the inherent risks in
marine operations the Warranty Surveyor will have to
base the final approval on Site Survey prior to each
operation. Only in case of repetitive marine operations
the Site Surveys may be replaced by an Audit Scheme.
2.5.1.2 The basis for Approval in Principle is
implementation of QA systems according to the ISO
9000 series. For vessels involved in the operation this
may be covered by the Safety Management Class
requirements introduced by DNV or the ISM
(International Safety Management) Code presented by
IMO (International Maritime Organisation).
2.6.l.3 The typical work methods of the Quality
Surveyor are in addition to the Warranty Surveyor tools,
see 2.2.1;
perform HAZOP studies, risk analysis etc.,
carry out independent verifications including
separate analyses as p8fls of the design
evaluation,
carry out onhire/oflbire surveys, and
perform quality certification of
designers andlor builders,
operators for marine operations.
2.6.2· Marine advisory services
2.6.2.1 The Marine Advisor is the consultant in a
marine operation project who is appointed to support the
Operator or Contractor in agreed aspects relevant to
design, fabrication or operation.
2.5.1.3 The additional requirements are approval of
documentation and procedures worked out for the type
of marine operations to be carried out under tbis scheme
and qualification certification of the involved personnel,
including documented knowledge of the relevant parts of
these Rules.
2.6.2.2 In order to avoid any possible conflict of
interest the Warranty Surveyor shall not be involved in
Maruie Advisory covering e.g. direct design assistance
or any other work that be may later receive for approval.
2.5.1.4 Only possible deviations from the approved
procedures shall be submitted for approval in each case.
The minimum requirement is that a yearly renewal audit
of the Approval in Principle scheme shall be carried out,
e.g. connected to performance evaluation of a selected
marine operation.
DET NORSKE VERITAS
Rules for Marine Operations
January 1996
, !Page 10 of 12
Pt.l Ch.l Warranty Surveys
3. PROCEDURES FOR INSURANCE WARRANTY SURVEYS
3.1 ENGAGEMENT OFTIIE WARRANTY
3.3.1.2 The necessary plans, descriptions,
SURVEYOR
specifications, procedures, certificates, and other
required information·shall be submitted to the Warraoty
Surveyor. The minimum documentation required shall be
specified by the Warranty Surveyor and specific details
for the various types of marine operations are given in
Part 2.
3.1.1 Warranty contract partners
3.1.1.1 Although it is the Insurer who requires the
warranty, in practice it is usually the Assured who
engage and compensate for the service of the Warranty
Surveyor. The Assured being the Operator, the Owner,
or his Contractor.
3.3.1.3 The doc1lmentation shall be submitted in due
course of a marine operation allowing ample time for
review by the Warranty Surveyor.
, ) 3.1.1.2 A separate contract shall be entered into
between the Warranty Surveyor and the Assured in each
case. The terms of this contract shall be as set out in Pt. D
Ch.1 Sec. 1. 2. 2.
3.3.2 Document review
3.3.2.1 When the submitted documentation has been
reviewed, the Warranty Surveyor will inform the
Assured whether the planned marine operation can be
approved. Such approval may be on condition that
specified minor corrections Of modifications are made.
In case of more important corrections or modjfications.
submission of revised documentation will be reqJlired.
3.2 BASIS FOR WORK
3.2.1 Main or alternative methods
3.2.1.1 The marine operations undertaken shall comply
with these Rules. However, altel'Qative methods may he
acceptable, as specified in Pt.D Ch.1 Sec. 1.1.3.
3.3.3 Independent computer analysis
3.3.3.1 The most effective means of review of
submitted documentation, is in some cases to perform
3.2.2 Assumptions
\
independent computer analysis.
3.2.2.1 It is assumed that the planning and execution of
) marine operations are carried out by qualified personnel
and in accordance with sound principles, that the
activities during the marine operations are carried out by
Contractors having the required skill and experience, and
that adequate quality control is carried out.
3.3.4 Third party verification
3.3.4.1 The Warranty Surveyor may partly base his
work on material and component certificates as well as
vessel certificates issued by other independent third
parties.
3.2.2.2 The Contractors should therefore have
implemented the relevant parts of a Quality System, e.g.
according to the ISO 9000 series.
3.3 APPROVAL WORK
3.3.4.2 Approval or acceptance may also be based on
verification carried out by other third parties. However,
the Assured shall document for the Warraoty Surveyor
the basis Jor such verification, the scope of work and
qualifications of the verifying body.
3.3.1 Documentation
3.4 PREPARATION FOR OPERATIONS
3.3.1.1 The Warraoty Surveyor shall upon his
appointment make clear to the Assured the requirements
to fulfil the terms of warranty.
Guidance Note
For complex marine operations the Warranty Surveyor will identify
design and engineering document subject to review and approval
well in advance based on document lists submitted by the Assured,
3.4.1 Site surveys
3.4.1.1 Surveys by the Warranty Surveyor will be
carried out at the construction site(s) as required during
all temporary phases.
DEf NORSKE VERITAS
(.J
January 1996
Page 11 oC 12
Rules for Marine Operations
Pt.l Ch.l Warranty Surveys
3.4.1.2 The Warranty Surveyor will perform surveys
prior to the operation and may specify requirements to
be met in order to comply with the tenns of the
warranty. In some cases also survey of installation site
may be necessary in order to document that it is ready to
receive the object. The Warranty Surveyor will prepare
reports on all surveys.
3.4.4.4 In the event that the Warranty Surveyor for any
3.4.2 FUnctional testing
3.5.1 Surveillance of operation
3.4.2.1 Functional testing shall be carried out to the
extent it directly or indirectly affects the safety in any of
the respects mentioned in 1.4. The testing shall be
carried out according to test programmes approved by
the Warranty Surveyor.
3.5.1.1 The Assured shall ensure that the marine
operations are carried out in accordance w~th the
approved documentation.
3.4.2.2 Unless otherwise agreed, the testing shall be
carried out in the presence of the Warranty Surveyor.
reason is unable to issue a Declaration, both the Assured
and Insurer shall be informed that the requirements in
the warranty clause not can be met or fulfilled.
3.5 ATfENDANCE DURING OPERATION
3.5.1.2 Any deviation from approved plans during the
operation shall be considered as a change to the marine
operations manual. Such changes shall be presented to
attending Warranty Surveyor for approval and the
deviation duly recorded in the marine operations log.
3.4.3 Vessels and equipment certification control
3.4.3.1 All vessels involved in marine operations shall
be well suited Cor the tasks and have relevant valid
classification and nag state certificates which are to be
presented to the warranty surveyor t upon request.
3.4.3.2 Equipment and components involved in the
marine operations and of particular importance to the
safety of the operations shall have valid certificates
specifying the relevant capacities.
3.4.4 Issuance of marine operation declarations
3.4.4.1 When the required documentation has been
approved, the prevailing conditions have been found
acceptable, and the surveys completed to the Warranty
Surveyor's satisfaction, a Marine Operation Declaration
will be Issued on a special form prior to start of the
operation, see 1.5.1.
3.5.1.3 In marine operations the weather forecast is of
particular importance and should be compared to the
limiting weather criteria specified in the Marine
Operation Declaration issued for the operation. In case
of sudden weather changes not forecasted the attending
Warranty Surveyor may witness if the approved
procedure has been followed.
3.5.2 Breach of warranty
3.5.2.1 Deviations from approved procedures may
result in a breach of warranty sitnation. This sitnation is
described in 1.6.
3.6 NEEDS AND DUTIES OF PARTIES
INVOLVED
3.6.1 Difference of opinion
3.4.4.2 For more complex marine operations, several
Declarations may be issued by the Warranty Surveyor in
order to cover all phases of the operation. Each
Declaration will in such cases specify the activities
which are covered and be issued immediately prior to
start of those activities.
3.4.4.3 The Marine Declaration will be in Corce until
the operation defined in the Declaration has been
completed, e.g. saCety moored, lifted object saCely
landed and secured.
3.6.1.1 In most cases the parties involved (Insurer,
Assured, Warranty Surveyor and Authorities) have the
same interest regarding safety aspect related to marine
operations. However. difference of opinion may occur.
In order to avoid any possible conflict of interest the
Warranty Surveyor shall therefore have a well defined
scope of work and carry out his task in accordance with
these Rules.
3.6.1.2 The needs and duties of the different parties are
specified in the Sections above, therefore only some
additional aspects are emphasised in the following.
DET NORSKE VERITAS
Rules for Marine Operations
Pt.1 Ch. 1 Warranty Surveys
January 1996
Pagell ofll
3.6.2 Duties of insurer
3.6.2.1 The losurer should propose level of Warranty
for the different types of marine operations to be
insured, based on previous experience or dialogue with a
Warranty Surveyor and specify this in the Insurance
Warranty Clause.
3.6.2.2 The losurer will be preseoted a list of Marine
Surveyors considered pre-qualified by the Assured to
tender for W,arranty Surveys. At that time the Insurer
has the possibility to reject proposed Warranty
Surveyors based oil objective non-discriminating criteria.
o
3.6.3 Duties of assured
)
3.6.3.1 The Assured sball select a Warranty Surveyor
among those pre-qualified and accepted by the losurer.
3.6.3.2 It is the duty of the Assured to inform the
Warranty Surveyor of the warranty cooditioos for the
project, including the level of warranty for each marine
operation, as proposed by the Insurer.
3.6.3.3 The Assured is responsible in relation to the
losurer for all ilspect of the marine operation, and shall
give the Warranty Surveyor alillecessary documentation
and support.
3.6.4 Duties of warranty surveyor
3.6.4.1 The Warranty Surveyor is contracted solely for
the purpose to warrant that the requirements of the
Insurer as expressed in the Warranty Clause are fulfilled.
It is emphasised that the Warranty Surveyor is there to
approve the operauon(s), not to perform tbem.
)
DET NORSKE VERITAS
RULES FOR
PLANNING AND EXECUTION OF
)
MARINE OPERATIONS
PART 1 : GENERAL REQUIREMENTS
o
)
o
PART 1 CHAPTER 2
PLANNING OF OPERATIONS
JANUARY 1996
SECTIONS
G
1. INTRODUCTION ........ ........................ ...... ........................................•........................... : ........ 5
2. PLANNING ..........•..•. . ••...•................. ...................•....••..•......•.•..••.....••........... ••. .................... 7
3. OPERATIONAL REQUIREMENTS ... .............. . ....................... ............................ .............. ........ 10
4. STABIliTY REQUIREMENTS ... . ...................................................• ... ........................ .............. 14
5. SYSTEMS AND EQUIPMENT ...................................................................... : .. ... ..................... 19
DET NORSKE VERITAS
Veritasveien 1, N-1322 H""ik, NOIway Tel.: +4767579900, Fax.: +47675799 II
CHANGES IN T,HE RULES
This is the first issue of tbe Rules for Planning and
Execution of Marine Operations, decided by tbe Board
ofDet Norske Verita. 'ClassificatiOli NS as of December
1995. These Rules supersedes tbe June 1985, Standard
fo~ Insurance Warranty Surveys in Marine Operations.
.
.
These Rules come into force on 1st of January 1996.
This cbapter is valid until superseded by a revisOd .
cbapter. Supplements to tbis cbapter will not be issued
except for minor amendments and an updated 'list of
corrections presented in tbe.introduction booklet. · .'
Users are advised to cbeck tbe systematic i,;~eil; irl.the
introduction booklet to ensure tbat tbat 'ih~ 'cb~pieds
current.
)
)
Det Non;ke Veritas
Computer Typesetting by Det Norske Veritas
Printed in Norway by the Det Norske Veritas January 1996
@
January 1996
Page 3 of 23
Rules for Marine Operations
Pt.1 Ch.2 Planning of Operations
CONTENTS
1.
INTRODUCTION ........•..... •.....•..•.•.•.....• 5
3.5
MARINE OPERATION MANUALS ........... 13
3.5.1 General .............................. .. ........ 13
1.1
GENERAL ........................... ................ . 5
1. 1. 1 Application .................................... 5
1.1.:l Regulations, codes and standards .... ...... 5
4.
STABILITY REQUIREMENTS ... ........... 14
4.1
GENERAL REQUIREMENTS ............. , .... 14
4.1.1 Stability and reserve buoyancy ............ 14
4.1.2 Temporal)' closing elements ............... 14
4.1.3 Stability calculations ........................ 14
4.1.4 Inclining tests ................................ IS
4.1.5 Watertight integrity ......................... 15
4.2
BARGE TRANSPORTS ...... ..................... 15
4.2.1 Safety against entry of water ............... IS
4.2.2 Intact stability requirements ............... IS
4.2.3 Single barge damage stability
requirements . ........................ ........ ........ 16
4.2.4 Multi barge damage stability
requirements ................... .. ............. ....... 17
4.3
SELF FLOATING STRUCTURES .............. 17
4.3.1 General ........................................ 17
4.3.2 Intact stability requirements ..... : ......... 17
4.3.3 Damage stability requirements ............ 17
4.4
LOAD OUT OPERATIONS ...................... 17
4.4.1 General ........................ ...... . .. .. ..... 17
4.5
ornER VESSELS ................................. 18
4.5.1 General ............................... : ........ 18
5.
SYSTEMS AND EQUIPMENT ................ 19
1.2
DEFINITIONS
5
1.2.1 Terminology .................................. . 5
1.:l.:l Symbols ............ . ........................... 6
2.
PLANNING .......................................... 7
2.1
PLANNING PRINCIPLES .... .................... 7
2. 1.1 Philosophy ..................................... 7
2. 1.2 Planning and design sequence .............. 7
2.1.3 Design basis and design brief.. ............. 7
2.2
DOCUMENTATION .................. .. ....... .... 8
:l.2.1 Documentation requirement.. .............. . 8
:l.2.2 Documentation quality ...... ............ ..... 8
2.2.3 Input documentation .................... ..... 8
2.2.4 Output documentation ............ .... ....... 8
2.2.5 Operation records .. ........................... 8
00'. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
)
2.3
RISK EVALUATIONS ............................. 9
2.3.1 General ...... ....................... . .... ..... .. 9
2.3.2 HAZOP study ................................. 9
2.4
MARINE OPERATION DECLARATION ...... 9
2.4.1 General ......................................... 9
2.4.2 Review scope ...... ...... .................. .... 9
3.
OPERATIONAL REQUIREMENTS ......... 10
5.1
3.1
OPERATION AND DESIGN qUTERIA ...... 10
3.1.1 Operation reference period ............ .. ... 10
3.1.2 Weather restricted operations .............. 10
3.1.3 Unrestricted operations ..................... 10
SYSTEM DESIGN ................................. 19
5.1.1 General ........................................ 19
5.1.2 Back up ........................................ 19
5.2
WEATIIER FORECAST .......................... 11
3.2.1 General ................................ .. ...... 11
3.2.2 Weather forecast levels ..................... 11
3.2.3 Monitoring of environmental conditions. 12
VESSELS AND BARGES ........................ 19
5.2.1 General ........... .. .. .... ..................... 19
5.2.2 Towing vessels ............................... . 20
5.2.3 Barges ........ .. ............................... 20
5.3
MOORING SySTEMS ............ ........ ........ 20
5.3.1 General ........................................ 2O
5.3.2 ULS conditions ........ ....... .. ... .......... 20
5.3.3 PLS conditions ... : .. .... ..................... 21
5.3.4 FLS conditions ............................... 21
5.3.5 Mooring line strength ....................... 21
5.3.6 Mooring details .............................. 21
5.3.7 Anchors ....................................... 22
3.2
3.3
ORGANISATION .................................. 12
3.3.1 Organisation and responsibility .......... . 12
3.3.2 Communication ........ .... .................. 12
3.3.3 Shift plan ...................................... 12
3.4
PREPARATION AND TESTING .. ............. 12
3.4.1 Testing ...... .............................. .... 12
3.4.2 Familiarisation and briefing ................ 13
DIIT NORSKE VERIT AS
January 1996
n
Rules for Marine Operations
Pt.l Ch.2 Planning of Operations
Page 4 of 23
5.4
GUIDING AND POSmONING SYSTEMS ..
5.4. 1 General ......... . ................... . ... .. . ...
5.4.2 Characteristic loads .. ............... ..... . ..
5.4.3 Design strength .. .... ............ .. .. ... ... ..
22
22
22
23
Table List
Table 3 .1 - Significant wave height - tv. values ... .... 10
Table 3.2 - Weather Forecast Levels ........ .... ....... 11
Figure List
Figure 2 . 1 - Planning and Design Sequence ............ 7
Figure 4.1 - Illustration of Stability Terms ............ 16
Figure 4.2 - Intact Stability requirement. .............. 16
Figure 4.3 - Damage Stability Requirements .......... 17
)
DIIT NORSKE VERITAS
Jannary 1996
Rules for Marine Operations
Pt.l Ch.2 Planning of Operations
PageS of 23
1. INTRODUCTION
ONV Rules for Classification of Mobile Units,
ONV Rules for Classification of Steel Ships.
Supporting documents to these publiealions such
as Appendices, Guidelines, Classification Notes,
and Certification Notes.
1.1 GENERAL
1.1.1 AppliCation
1.1.1.1 Pt.l CiJ.2, Planniog of Operations, gives
requirements and recommendations for planning,
preparations and performance of marine operations.
o
l.
1.2 DEFINITIONS
1.1.1.2 Recommendations and requirements for desigo
loads and loads cases are given in Pt. 1 Ch.3, and for
structural verifications in Pt. 1 Ch.4.
1.2.1.1 General definitions of terms are included in
Pt. D Ch.l. Terms considered to be of specIal
importance for this chapter are repeated below.
) 1.1.1.3 Operation specific requirements and
recommendations are given in Pt.2 of these Rules.
1.1.1.4 Recommendations and requirements in these
Rules shall be considered in relation to the structural and
operational complexity, sensitivity and type of marine
operation to be performed.
1.1.1.5 Application of equipment and execution of
operations not adequately covered by these Rules shall
be specially considered in each case.
1.1.1.6 General conditions for using these Rules are
stated in Pt.D CiJ.l Sec 1.2.
1.1.2 Regulations, codes and standards
1.1.2.1 These Rules should be used together with other
recognised codes or standards applicable for marine
o
1.2.1 Terminology
Design: An activity to create or form layout's,
concepts, arrangements or structures.
Design criteria: The criteria applied for verification of
systems, equipment, structures etc. for the planned
maririe operation.
Fail safe: A configuration which upon failure of
elements remain in a controllable and safe condition.
Independent third party verification: Verification
activities performed by a body independent from
company and contractor ~ .
Marine Operation Declaration : A written confirmation
stating compliance with these Rules of equipment,
temporary and permanent structures, handled object,
procedure, preparations etc.
operations.
Object: The structure handled during the marine
operation, typically a module, deck structure, jacket,
In case of conflict between other codes or standards, and
GBS, sub sea structures, pipes,
this document, the latter shall override if this provide a
higher safety or serviceability.
etc.
Operation: A planned marine operation, with defined
start- and termination point.
1.1.2.2 By recognised codes or standards are Djeant
national or international codes or standards applied by
the majority of professional people and institutions in the
marine and offshore industry.
Operation criterio : The acceptance criteria for start of
the planned operation.
1.1.2.3 Examples of applicable rules and regulations,
Single critical element: Non-redundant eleDjent, which
failure constitute failure of the structure/system.
codes or standards are;
SOLAS,
MARPOL,
IMO regulations, and
ISO and national standards.
NMO Rules and Regulations,
NPO Rules and Regulations,
Safe condition: A condition where the object is
considered exposed to "normal" risk for damage or loss.
Unrestricted operations: Operations with characteristic
environmental conditions estimated according to long ·
tenn statistics.
OET NORSKE VERITAS
January 1996
Page 6 of 23
Rules for Marine Operations
pt.1 Ch.2 Planning of Operations
Verification: Activity to confirm that a design,
product/equipment, structure or procedure complies with
defined standards amI/or specifications. Verification
may be documented by calculations, analysis,
certificates, survey reports and inspection reports.
Weather restricted operations: Operations with defined
restrictions to the characteristic environmental
conditions, planned performed within the period for
reliable weather forecasts.
1.2.2 Symbols
'The list below define the symbols used in this chapter:
Design criteria.
Co:
Co:
Operation criteria.
GM:
Initial metacentric height.
Righting arm, a function of heel angle.
Significant wave height.
Operation reference period.
Planned operation period.
Estinaated contingency time.
Ultimate limit state.
Progressive limit state.
Fatigue limit state.
Operation/design criteria ratio.
Total displacement.
Mean displacement.
FlfSt order motion due to waves,
Material factor.
Positive GZ range.
Maximum dynamic heel angle due to wind and
GZ:
H. :
TR :
TPOp:
Tc:
ULS:
PLS:
FLS:
CL:
0"" :
Bmmn :
Omotioa. :
'Ym:
<I> :
<1>-:
waves.
)
DET NORSKE VERITAS
c
Rules for Marine Operations
Pt.1 Ch.2 Planning of Operations
January 1996
Page 7 or 23
2. PLANNING
2.1 PLANNING PRINCIPLES
Develop design briefs describing activities
planned in order to verify the operation, i.e.
available tools, planned analysis including
method and particulars, applicable codes,
2.1.1 Philosophy
2.1.1.1 Marine operations shall be planned and
prepared to bring an object from one defined safe
condition to another according to safe and sound
practice, and according to defined codes and standards.
2.1.1.2 Planning of marine operations shall be
according to fail safe principles, i.e. the handled object
shall remain in a stable and controlled condition if a
acceptance criteria, etc.
Carry out engineering and design analyses.
Develop operation procedures.
2.1.2.2 The indicated sequence is illustrated in Figure
2.1. Planning and design should be considered as an
iterative process.
failure situation should occur.
Q(
2.1.1.3 It should be possible to recover the object into a
safe condition, or interrupt the operations in case of a
possible failure situation.
For operations passing a point where the operation can
not be reversed, a point of no return shall be defined.
Safe conditions after passing a point of no return shall be
defined and considerde in the planning.
2.1.2.3 Applicable input, and planned output
documentation should be defined as early as possible,
see also 2.2.3 and 2.2.4.
Figure 2.1 - Planning and Design Sequence
Regulations, Rules
Specifications, Standards
2.1.1.4 All possible contingency situations .hall be
identified, and contingency plans or actions shall be
prepared for these situations. Such plans .hall consider
redundancy, back-up equipment, supporting personnel,
emergency procedures and other relevant preventive
measures and actions. Contingency situations may be
defined'or excluded based on conclusions from risk
evaluations, see 2.3.
l
Overall Planning
Design Brief &
Design Basis
Engineering &
Design Verification
2.1.1.5 Design and planning for marine operations shall
as far as possible be based on well proven principles,
techniques, systems, and equipment.
Operational Procedure
2.1.2 Planning and design sequence
2.1.2.1 It is recommended to adopt the following
sequence for tbe planning and design process:
Identify relevant regulations, rules, company
specification., codes and standards.
Identify physical limitations.
2.1.3 Design hasis and design hrief
2.1.3.1 It is recommended to develop a design basis
andlor a design brief in order to obtain a common basis
and understanding all parts involved during design,
engineering and verification.
Overall planning of operation i.e. evaluate
operational concepts, available equipment,
limitations, economical consequences, etc.
Develop a design basis describing
environmental conditions and physical
2.1.3.2 The design basis should describe the basic input
parameters, characteristic environmental conditions,
cbaracteristic loadslload effects, load combinations and
load cases.
limitations applicable for the operation.
DET NORSKE VERITAS
January 1996
Rules for Marine Operations
Pt.l Ch.2 Planning of Operations
Page 8 of 23
2.1.3.3 The design brief should describe the planned
2.2.2.3 The quality and details of the documentation
verification activities, analysis methods, software tools,
input specifications, acceptance criteria, etc.
shall be such that it allow for independent reviews of
plans, procedures and calculations, for all parts of the
operation.
Guidance Note
The DeSign Basis and the Design Brief-may be combined and
issued as one document.
Guidance Note
Guidance Note
A document plan describing document hierarchy and scope for each
document is recommended (or major marine operations.
It Is recommended to include the DesIgn Basis and the Design
Briefs as part of the formal documentation for the operation, and
subject for review and approval according to projecUoperation
2.2.3 Input docwnentation
requirements.
2.2.3.1 Applicable input documentation, such as;
slatetory regulations,
rules,
2.2 DOCUMENTATION
company specifications,
standards and codes,
2.2.1 Docwnentation requirement
concept descriptions,
2.2.1.1 Acceptable characteristics sball be documented
for the handled object and all equipment, temporary or
permanent structures, vessels etc. involved in the
basic engineering results (drawings, calculations,
etc.), and
relevant contracts or parts of contracts.
should be identified before any.design work is
performed.
operation.
Guidance Note
Note that all elements of the marine operation shall be documented.
This also Include onshore facilities such as quays, soli, pullers and
foundations.
2.2.4 Output docwnentation
2.2.1.2 Properties for object, equipment, structures,
2.2.4.1 Necessary documentation shall be prepared to
vessels etc. may be documented with recognised
certificates. The basis for the certification shall then be
clearly stated, i.e. acceptance standard, basic
assumptions, dynamics considered etc., and comply with
the philosopby and intentions of these Rules.
prove acceptable quality of the intended marine
operation. Typical output documentation are:
Planning documents including design briefs and
basis, schedules, concept evaluations, general
arrangement drawings and specifications.
Design documentation including load analysis,
global strength analysis, local design strength
calculations, stability and ballast Calculations
and structural drawings.
2.2.1.3 Design analysis should typically consist of
various levels with a "global" analysis as top level, and
with strength calculations for details as a lowest level.
Different types of analysis metbods and tools may apply
for the different levels.
Operational procedure including testing
program and procedure, operational plans and
procedure, arrangement drawings, safety
requirement and administrative procedures.
2.2.1.4 Operational aspects sball be documented in
form of procedure, operation manuaJ,s, certificates,
calculations etc. Relevant qualifications of key
personnel shall be documented.
Certificates, test reports, survey reports, NDE
documentation, as built reports, etc.
2.2.1.5 All relevant documentation shall be available
aD site during execution of the operation.
2.2.5 Operation records
2.2.5.1 Execution of marine operations shall be logged.
2.2.2 Docwnentation quality
Samples of planned recording forms shall be included in
2.2.2.1 The documentation shall demonstrate that
the marine operations manual.
philosophies, principles and requirements of these Rules
are complied with.
2.2.2.2 Documentation for marine operations shall be
,
)
self contained, or clearly refer to other relevant
documents.
DEf NORSKE VERITAS
January 1996
Page 10 of 23
Rules for Marine Operations
Pt.I Ch.2 Planning of Operations
3. OPERATIONAL REQUIREMENTS
3.1 OPERATION AND DESIGN CRITERIA
3.1.2.3 For weather restricted operations these Rules
consider uncertainties in weather forecasts by applying a
operation criteria less than the design criteria. The
operation criteria should be taken as;
3.1.1 Operation reference period
3.1.1.1 Planniog and design of marine operations shall
be based on an operation reference period defined as;
Eq.3-2
TR=TPOp+Tc
Eq.3-1
where
TR - Operation reference period
T pop - Planned operation period
)
Tc -
where
Co - design criteria,
Co - operation criteria,
a. operational vs. design criteria ratio,
for significant waves, ex. should be taken
according to Table 3.1.
for wuid (10 llIin. mean),
0.80.
Estimated contingency time.
3.1.1.2 Reference periods less than 12 hrs. should be
specially considered.
The start and termination points for the intended
operation sball be clearly defined.
not assessed the reference period. may be taken as twic_e
the planned operation period, but not less than 6 Ius.
3.1.2 Weather restricted operations
)
3.1.2.1 Marine operations with a reference period, less
than 72 hours may be defined as weather restricted.
These operations may be planned with environmental
design conditions selected independent of statistical data,
Le. set by owner, operator etc. Start of weather
restricted operations are conditional to a acceptable
weather forecast, see 3.2.1.5.
should be taken as
For operations planned according to 3.1. 2. 2 the factor CL
should be specially considered in each case.
Table 3.1 - Si!!nificant wave
3.1.1.3 If required time for contingency situations are
(l.
hei~ht
- (l. values
', 9ii~~~oxial ' : ! .;,';;· DeJi;; \iia~~H~ii$i" [J;l · ·
.
ii.~#f#:!liii~]~: '; l~~gili,;: '2:'f~~ 1 · . ;~.:~ 4.,~
TR
<
12
0.68
0.76
0.80
TR
<
24
0.63
0.71
0.75
TR
<
48
0 .56
0.64
0.67
TR
< 72
0.51
0.59
0 .63
Note: Table 3.1 is based on DNMI report DS0265/LUND·95/15325,
dated 95-05-04 verifying forecasted wave heights at Ekofisk and
Statfjord.
.3 .1.3 Unrestricted operations
Guidance Note.
Environmental conditions should be selected based on an overall
evaluation of possible waiting on weather costs/probabilities,
structural capacities, operational aspects etc, Too strict
environmental conditions should be avoided.
3.1.2.2 Operations with a operation reference period
exceeding 72 hours may be defined as weather restricted
if a continues surveillance of actual and forecasted
weather conditions are specified in the operation
procedure, and the operation can be interrupted and the
haodled object brought into a safe condition within the
forecasted period if adverse environmental conditions are
3.1.3.1 Marine operations with a operation reference
period, exceeding 72 hours are norrnalIy defined as UQ.
restricted operations. Environmental criteria for these
operations shall be based on extreme value statistics, see
Pt.1 Ch.3 Sec. 2. The operation criteria for these
operations may be taken equal to the characteristic
environmental conditions .
Guidance Note
Note that certain operations require a start criterion although
designed for unrestricted conditions. Further information is given for
the respective operations in Pi.2.
forecasted Of experienced.
Characteristic environmental condition shall in these
cases be based on a duration equal to the accumulated
operation period, i.e. not on estimated time for each
single sequence or leg.
DEl' NORSKE VERITAS
January 1996
Page 11 of 23
Rules for Marine Operations
pt. 1 Ch.2 Planning of Operations
3.2 WEATHER FORECAST
Level A
Weather forecast level A include major marine
operations sensitive to environmental conditions.
3.2.1 (}eoeral
3.2.1.1 Arrangements for receiving weather forecasts at
regular intervals prior to, and during the marine
operations shall be made. Such weather forecasts shall
be obtained from recognised sources.
3.2.1.2 Weather forecast procedures should consider
the nature and duration of the planned operation, see
Typical "level A" operations may be;
mating operations,
multi barge towing,
GBS tow out operations,
offshore installation operations, and
jackup rig moves.
3.2.2.1.
Level B
The weather forecasts shall be in writing.
operations of significant importance with regard to value
Weather forecast level B include environmental sensitive
and consequences.
3.2. 1.3 10 addition to a general description of the
) weather situation and the predicted development, the
weather forecast shall, as relevant, include;
Typical "level B n operations may be;
float out operations,
offshore lifting,
wind speed and direction,
waves and swell, significant and maximum
height, mean or peak period and direction,
ram, snow, lightning, ice etc. ,
sensitive barge towing,
Level C
Weather forecast level C include conventional marine
tide variations and/or storm surge.
operations less sensitive to weather conditions, and
carried out on a regular basis_
visibility ,
temperature, and .
barometric pressure
Typical "level C" operations may be;
for tlie coming 12, 24, 48 and 72 hrs. 10 addition an
outlook for the next days should be included.
3.2.1.4 The forecast sball clearly define forecasted
parameters. e.g. average time for wind, characteristic
wave periods (T, or T.,).
3.2.1.5 A weather forecast is acceptable for start of
marine operations if all relevant items listed in 3.2. 1.3
are within the defined operational criteria for the
onshore/inshore lifting,
load out operations,
tows in sheltered waterslharbour tows and
standard barge tow without weather restrictions.
3.2.2.2 Based on selected weather forecast level, a
forecast procedure complying with requirements in Table
3.2 should be established.
Table 3.2 - Weather Forecast Levels
operation reference period.
3.2.1.6 The weather forecasts shall be assessed
according to a worst case scenario.
This is particularly important for unstable weather
situations and for forecasts which are considered to be of
low confidence.
3.2.2 Weather forecast levels
3.2.2.1 Based on evaluations of the operational
sensitivity to weather conditions, a categorisation of the
operation into weather forecast levels A, B or C shall be
made.
A
Yes
2
3)
12 Hrs' ).
B
No')
2
12 Hrs.
C
No
1
12Hrs.
1) Based Qn sensitiVity w.r.t. weather conditions smaller intervals
may be required.
2) ContacVdiscussions with meteorologist shall be made.
3) A written rorecast from only one of the sources may be
acceptable.
Guidance Note
Independence between weather forecast sources is satisfied ir there
are organisational independence between the sources, i.e. it is
acceptable to obtain a second rorecast from a national and a local
source (relevant for the actual area).
DET NORSKE VERITAS
()
January 1996
Page 12 of 23
Rules for Marine Operations
Pt.l Ch.2 Planning of Operations
3.2.3 Monitoring of environmental conditions
3.3.1.6 Operations shall be carried out in accordance
with the conditions for design, the approved
3.2.3.1 For marine operations particularly sensitive for
documentation, and sound practice, such that
certain environmental conditions such as waves, swell,
unnecessary risks are avoided. This is the responsibility
current, tide etc., systematically monitoring of these
conditions prior to and during the operation should be
arranged.
of the operation superintendent or manager.
3.2.3.2 Monitoring should be systematic.
Responsibilities, monitoring methods and intervals
should be described in a procedure.
3.3.1.7 Responsibilities in possible emergency
situations shall be described.
3.3.1.8 Access to the area for the operation sbould be
restricted. Only autborised personnel should be allowed
into the operation area.
3.2.3.3 Essential monitoring systems should have back
up systems.
3.3.2 Communication
)
3.2.3.4 Predicted variations of these parameters during
executions of the marine operations should be based on
monitored variations, tabulated values and forecasted
variations.
3.2.3.5 Any unforeseen monitoring results should be
reported without delay.
3.2.3.6 Tidal variations should additionally be
monitored a period with the same lunar phase as for the
planned operation.
Guidance Note
Tide variations should be plotted against established astronomical
tide curves. Any discrepancies should be evaluated, duly
considering barometric pressure and other weather effects.
3.3.2. 1 Communication lines and primary and
secondary means of communication shall be defined,
preferably in a communication chart.
Important information sbould be dedicated to uninteruptable lines/channels.
3.3.2.2 The planned flow of information during the
operation shall be described. A common language
understood by all shall be used for VHFfUHF
communication.
Guidance Note
The communication chart shall reflect the actual communicaUon
lines that will be used during the operation.
Guidance Note
To avoid interference between internal andfor external users it is
recommended to allocate VHFIUHF channels as early as possible.
3.3 ORGANISATION
)
3.3.3 Shift plan
3.3.1 Organisation and responsihility
3.3.1.1 Organisation and responsibility of key
personnel involved in marine operations shall be
established and described prior to execution of marine
3.3.3.1 For operations with a planned duration (fpop)
exceeding 12 hours a shift plan shall be established.
operations.
3.4 PREPARATION AND TESTING
3.3.1.2 Organisation charts, including names and
functional titles of key personnel, shall be included in
the marine operations manual. Authority during the
operation sball be clarified.
3.4.1 Testing
3.4.1.1 All equipment and structures involved in
marine operations shall be inspeeted and tested in order
to confirm compliance with specifications, functional
3.3.1.3 CV's for supervisors and key personnel
involved in major marine operations shall be presented.
)
requirements and assumptions for the design.
3.3.1.4 Supervisors sball posses a thorougb knowledge,
and have experience with the actual operatioD type, see
3.4.1.2 All systems and their back up shall be tested
before the start of an operation. Such tests shall
demonstrate tbe reliability and the capacities of the
also 3.4.2.
systems.
3.3.1.5 Key personnel sball have knowledge, and
3.4.1.3 Change over from a primary to a secondary
systems shall be tested.
experience within their area of responsibility.
DET NORSKE VERITAS
Rules for Marine Operations
Pt.1 Ch.2 Planning of Operations
January 1996
Page 13 of 23
3.4.1.4 Instrumentation systems shall be calibrated and
3.5 MARINE OPERATION MANUALS
tested prior to the operation. The calibration procedure
may be subject for review.
3.5.1 General
3.4.1.5 The test and inspection program shall be
planned, and the results documented.
3.5.1.1 Operational procedure sball be developed for
the planned operation, and sball reflect characteristic
Guidance Note
environmental conditions, physical limitations, design
assumptions and tolerances. The operational procedures
The inspections and testing can be documented by survey and
inspection reports, filled In test check lists, test reports, etc.
3.4.1.6 For larger operations it is recommended to
develop a test/commissioning program specifying the
planned inspections and tests. The test program should
indicate expected characteristics, and state acceptance
criteria based on the design assumptions.
shall be descrihed in a Marine Operation Manual
covering all aspects of the operations. Such manual shall
include descriptions of, as applicable;
organisation,
communication routines and systems,
general arrangement,
operational procedures and plan of execution,
Guidance Note
Acceptance criteria for tests may also -be functional requirements.
contingency planning and emergency procedures,
permissible load conditions,
3.4.1. 7 For operations with complex
environmental operation criteria,
tolerances,
communication/reporting procedures, or where proper
information flo,¥ is vital, a "run through" of
communication routines is recommended.
Thi. training should be performed with the nominated
personnel and under conditions similar to what are
expected during the actual operation.
permissible draughts, trim, and heel and
corresponding ballasting plan,
systems and equipment including layout,
systems and equipment operational instructions,
vessels involved ,
tow routes and ports of refuge,
navigation,
weather and current/wave reporting,
3.4.2 Familiarisation and briefing
3.4.2.1 Operation supervisors shall familiarise
themselves with all aspects of the planned operations
and pos.es. a thorough knowledge with respect to
safety equipment,
recording and reporting routines,
sample forms,
check lists for preparation and performance of the
operation. and
test and coDllllissioning planes.
limitations and assumptions for the design.
3.4.2,2 Key personnel shall familiarise themselves with
the operations. A thorough briefing by the supervisors
regarding responsibilities, conimunication, work
procedures, safety etc. shall be performed.
3.5.1.2 Limiting criteria for marine operations or parts
thereof shall be clearly stated in the Operation Manual.
3.5.1.3 Documentation in tbe form of certificates,
Guidance Note
Briefings are recommended both for familiarisation with the planned
operation and as a "team building" effort.
release notes and classification documents for all ·
equipment and vessels involved in the marine operation
shall be enclosed andlor listed in the Operation Manual.
3.4.2.3 Other personnel participating in the operation.
shall be briefed, generally about the operation and
specially about safety and assigned taskslresponsibilities.
)
DET NORSKE VERITAS
January 1996
Page 14 ofn
n
Rules for Marine Operations
Pt.l Ch.2 Planning of Operations
4. STABILITY REQUIREMENTS
4.1 GENERAL REQUIREMENTS
4.1.2 Temporary closing elements
4.1.1 Stability and reserve huoyancy
4.1.1.1 Sufficient stability and reserve buoyancy shall
be ensured for all floating objects in all stages of the
marine operations.
4.1.2.1 Temporary closing devices, such as hatches,
blind flanges, access openings etc., that may he exposed
to slamming or sloshing shall be designed and verified
for such effectslloads.
Special considerations shall be made to securing of these
devices.
4.1.1.2 Both intact and damage stability shall be
documented.
4.1.1.3 The requirements to damage stability shall be
evaluated considering the operation procedure,
environmental loads and responses, duration of
)
operation, consequences of possible damage, etc.
4.1.1.4 Attention shall be paid to ingress of water
caused by e.g.;
impact loads from vessels, dropped objects, etc.,
mechanical system failure,
operational errors, and
deteriorating weather conditions.
4.1.2.2 All openings between buoyant compartments
that may eause progressive flooding of the object should
be closed during operatioDs.
4.1.2.3 Regular inspections or gauging of air pressure,
water level, draught, heel, trim, etc. in search for
leakage should be carried out during operations.
4.1.3 Stahility calculations
4.1.1.5 Sufficient stability should normally not include
the up-righting contribution from occasionally
submerged elements such as jacket legs hanging over the
barge sides. This contribution may, however r be
)
Type and securing of sealings/gaskets shall be carefully
considered. Relative movement between closing device
and supporting structure shall be considered.
included in special cases for the requirement given in
4.2.2.2 upon careful examination of the operational
parameters. The contribution of the buoyancy of cargo
elements in the stability calculations must be accounted
for in the seafastening loads.
4.1.1.6 Drainage openings to avoid unacceptable
accumulation of water should be considered. If drainage
openings are impractical, the stability of the barge
should be investigated considering this effect.
4.1.3.1 During the calculations of stability and reserve
buoyancy, due allowance shall be included to account for
uncertainty in mass, centre of gravity loeation, density
of ballast and ballasting water, and density of the sea.
4.1.3.2 Correction for free surface effects in tanks and
compartments containing liquids shall be included.
4.1.3.3 For operations where stability andlor reserve
buoyancy at some stage is critical, special consideration
shall be given to the duration of the critical condition,
the risk of possible hazards and to the mobilisation time
for - and amount of - back-up systems.
4.1.3.4 Calculations of motions and effect of wind as
input to 4.2.2.2,4..2.2.3 and 4.3.2.1 shall be for the
decisive desIgn condition as defined in Pt. 1 GII.3. ICnol
otherwise specified, the 1 minute average wind speed
shall be applied in the stability calculations. For
unrestricted operations in the North Sea area wind speeds
exceeding 41 mls need normally not be considered.
Guidance Note
The load factor can for stability considerations be laken as 1.0 when
calculating"wind heeling moments.
)
DET NORSKE VERITAS
January 1996
Rules for Marine Operations
Pt.1 Ch.2 Planning of Operations
,
Page 15 of 23
4.1.4 Inclining tests
4.1.4.1 Inclining tests shall normally be performed at
various stages during construction afloat and prior to
major marine operations to confirm the parameters
influencing the stability. This is particularly relevant
when the calculated value of the metacentric height is
close to the D)inimum acceptable value and if such a
minimum condition is obtained by the transfer of heavy
loads.
4.1.4.2 A detailed procedure for the tests should be
prepared considering the following:
)
Maximum allowable wind speed for execution
of the tests should he established prior to the
testing. This maximum value should normally
not exceed 3 m/sec.
4.1.4.5 For floating objects with large metacentric
height, an inclining test may not give sufficient accurate
results. The stability calculations may then be based on
the calculated weight and centre of gravity andlor on
results from a thorough weight control system enforced
during the construction.
4.1.5 Watertight integrity
4.1.5.1 The number of openings in watertight
bulkheads and decks shall be kept to a minimum.
4.1.5.2 Where penetrations of watertight decks, onter
walls, and bulkheads are necessary for access, piping,
ventilation, electrical cables, etc., arrangements shall be
made to maintain the watertight integrity.
The inclining angle should be of the order of
+/- 1deg. for large volum structures and 5 deg.
for conventional vesselslbarges.
4.2 BARGE TRANSPORTS
The angles should be measured by at least two
4.2.1 Safety against entry of water
pendulums, or one pendulum and one
electronic/optic~
device.
The draught should be such that the waterline
intersects the unit in a wallside area.
The effects of external forces due to wind,
waves, moorings, anchors, tugs, cranes, etc.,
should be considered and preferably monitored.
4.1.4.3 Before the test, a sensitivity analysis of the
parameters affecting the inclining test results should be
performed. Sucb parameters are draught, heel angle, sea
water density, inclining weights and distances moved,
variable wind speed, accuracy of the measuring
equipment, etc.
The sensitivity analysis should give the total expected
error on the position of the centre of gravity and also
indicate which parameters to monitor during the test.
4.1.4.4 Upon completion of the inclining test, a report
containing measurements/readings ~d corresponding
calculations of displacement (and light weight if
relevant), melacentric height (GM), and the position of
the centre of gravity of the structure, should be
prepared.
After execution of inclining tests, a proper weight
control system should be implemented and enforced until
the relevant marine operation is completed.
4.2.1.1 The requirements of The International
Conference on Load Unes, 1966 (lLLC 66) should be
complied wjth as applicable with respect ~o air pipes,
overboard and iDlet pipes ~hrough hull, and weather tight
securing of doors, hatches and other openings.
4.2.1.2 All doors, batches, windows and ventilators
shall be closed with their closing appliances, except
where use of such openings are necessary for a riding
crew. In this case, the closing appliances for the
openings in use shall be stored close to their respective
openings. Manholes to tanks should he closed. All
water tight doors in bulkheads should be closed.
Valves on the barge sides and bottom not in use during
the voyage should be closed. Pipelines leading
overboard without any closing appliances should be
blanked off.
All bilges should be clean and dry on departure.
4.2.1.3 Dry compartments and empty or slack tanks
which contribute significantly to the buoyancy of the
barge shall be fitted with sounding facilities.
4.2.2 Intact stability requirements
4.2.2.1 For single and multi barge tows the
requirements both in 4.2.2.2 and 4.2.2.3 should
normally be met during all stages of sea transportstion
operations.
DET NORSKE VERITAS
January 1996
Page 16 of 23
)
Rules for Marine Operatious
Pt. 1 Ch.2 Planniug of Opemtious
4.2.2.2 The stability should be positive to a heel angle
beyond equilibrium as given below:
<I> ~
(<1>_ +15+ 15/GM),
Fi!!W"e 4.2 - Intact Stability requirement
max. 40 degrees
ItITACr STABUTY
Eq.4-1
provided <1>= for the design environmental condition is
smaller or equal \0 the heel angle where the maximum
transverse righting moment occurs, otherwise:
<I>
~
Eq.4-2·
where
GM =
)
Rlghllng Moment
~
,
a
ffi
>
40 degrees
<1>_ =
(A .. 8) > 1.4 (9 + C)
vr~"07/
~/
maximum dynamic heel angle due to wind and
waves, see also Pt. 1 Ch.3.
initial metacentricbeight in metres.
EJ
~
~
K
1m ANC1.E
(
4.2.3 Siugle barge damage stability requirements
Fi ure 4.1 - Dlustration of Stabili
Terms.
4.2.3.1 Damage stability evaluations shall be based on
damage scenarios according \0 identified contingency
situations, see 2.1. 1. Collision, leakage and operational
failure situations shall be evaluated.
Righting Arm (GZ)
As a minimum the barge should bave an acceptable
stability and reserve buoyancy, and remain floating in an
acceptable manner with anyone submerged or partly
submerged compartment flooded.
GM
Heel Angl
4.2.3.2 The acceptable floating condition is determined
by the following:
the angle corresponding to the second intercept of
The design resistance of any part of the barge,
cargo seafastening or grillage should not be
exceeded.
The barge should have sufficient freeboard
considering environmental effects to any open
the two curves,
compartment, where flooding may occur.
the angle of progressive flooding, or
the angle at which overloading of a structural
The area under the righting moment curve should
be greater than the minimum area under the wind
member occurs.
heeling moment curve up to :
the second intercept, or
4.2.2.3 The areas under the rigbting moment curve and
the wind beeling moment curve should be calculated up
to an angle of heel which is the least of;
)
The area under tbe righting moment curve should not be
less than 1.4 times the area under the wind heeling
moment curve.
This stability requirement (A+B) ~ 1.4 (B+C) is
illustrated in Figure 4.2 where the righting moment
curve is included in the sarne diagram.
4.2.2.4 For marine operations of very short duration
(for instance harbour moves and out of dock operations)
covered by reliable weather forecasts, an exemption from
the down flooding angle, whichever is less, see
Figure 4.3.
4.2.3.3 The consequences of a damage stability
situation should be thoroughly evaluated, in particular
witb respect to;
progressive flooding,
local strength of watertight boundaries and
loads on seafastening.
the requirements given in 4.2.2.2 may be acceptable
provided that adequate safety is eusured. However, the
stability should be positive to a heel angle 15 degrees
beyond equilibrium. Such situations are subject to DNV
acceptance.
)
DET NORSKE VERITAS
,
'i
Rules for Marine Operations
January 1996
Page 17 of 23
l't.1 Ch.2 Planning of Operations
I
Fieure 4.3 - Damaee Stabilitv Reouirements
4.3.2 Intact stability requirements
4.3.2.1 The following requirements sbould be met by
the self-floating object:
DAMAG£D SU.BUTY
(A+B»(B+C)
Righting t,lamenl
~
Z
'"0>
>
The initial metacentric height, GM, corrected for
free surface effects and effect of possible air
cushion should be at least LOrn.
The requirements to intact stability in 4.2.2
apply. For large concrete gravity base structures
a reduced ratio between righting moment and
heeling moment of 1.3 may be used.
Special consideration sbould be given to the
bydrostatic stability and motions ciuring transfer
of beavy loads to a floating structure both under
w~"om/
~
/
~
EJ~1"
1m. ""'"'
normal conditions and in case of an accidental
} 2.4 Multi barge damage stability requirements
)
load transfer.
4.2.4.1 Damage stability evaluatioos sball be based on
4.3.3 Damage stability requirements
damage scenarios according to identified contingency
situations, see 2.1.1. Collision, leakage and operational
failure situations sball be evaluated.
4.3.3.1 General requirements to damage stability given
in 4.2.3 apply.
As a minimum tbe harges with tbe transported object
sbould remain afloat in stable equilibrium with sufficient
freeboard to preclude progressive flooding with anyone
damage scenarios according to identified contingency
situations, see 2.1.1. Collision, leakage and operational
compartments open to the sea.
failure situations sball be evaluated.
The acceptable floating condition is determined by tbe
following:
remain afloat in a stable equilibrium with sufficient
)
The requirements of 4.2.3.2 apply.
The steady angle of beel or pitch caused by tile
damage nod win~ pressure sbould not immerse
any non watertight closures in the hull.
It shall be demonstrated by calculation that the
flooding of anyone compartment will not cause
the damaged barge to e~ange its heel or trim angle
relative to the overall heel or trim of the barge
unit, i.e., the damaged barge should not pivot
around any of the deck supports and thus loose
contact with the deck at other support(s).
4.3.3.2 Damage stability evaluations shall be based on
As a minimum tbe self-floating object shall normally
freeboard to preclude progressive flooding witb anyone
compartment open to the sea, as given in 4.2.3.2.
Exemptions from this requirement are not acceptable
unless adequate, approved precautions are taken. The
precautions should ensure acceptable safety, for instance
as given in 4.3.3.3 andlor 4.3.3.4.
.
4.3.3.3 If 4.3.3.1 cannot be complied with, the
structure sball witbstand the collision loads according to
Pt. 1 Ch.3 Sec.3, on the whole exposed circumference of
the structure from 5 metres below to 5 metres abOve any
operation waterline without ingress of water.
)
4.3.3.4 During moored construction pbases,
compliance with 4.3.3.3 may be obtained by sufficient
fendering in the waterline area.
4.3 SELF FLOATING STRUCTURES
4.3.1 General
4.3.1.1 This sub-section applies to objects such as
gravity base structures, jackets, offshore towers, etc.
supported by their own buoyancy during towing and
4.4 LOAD OUT OPERATIONS
construction afloat.
4.4.1 General
4.3.1.2 The requirements in 4.2.1 apply.
4.4.1.1 Load out operations sball be performed with a
minimum inital GM = 1.0 m. The requirements in
, . 3.1.3 Inclining tests for the floating object should be
4.2.2.3 and 4.2.2.4 apply .
..,erformed prior to marine operation to confirm the
position of centre of gravity, see 4.1.4.
DE! NORSKE VERITAS
January 1996
rage 18 of 23
Rules for Marine Operations
Pt.l Ch.2 Planning of Operatipns
4.4.1.2 Special attention shall be paid to the influence
of slack Uwks on stability afloat during the load out
operations.
4.5 OTHER VESSELS
4.5.1
<7eneraJ
4.5.1.1 Other vessels, semi submersibles, crane vessels,
etc., involved in marine operations shall, for both intact
and damaged conditions, comply with national or
international (IMO) stability regulations or codes.
4.5.1.2 Approved stability calculations according to
4.5.1.1 .ball be presented upon request prior to the
' eration.
(
)
DET NORSKE VERITAS
,
January 1996
Page 19 of 23
Rules for Marine Operations
,....... Pt. 1 Ch.2 Planning of Operations
5. SYSTEMS AND EQUIPMENT
5.1.2 Back up
5.1 SYSTEM DESIGN
5.1.1 General
5.1.1.1 Systems and equipment shall he designed.
fabricated, installed, and tested in accordance with
relevant codes and standards., see 1.1.2.
o
5.1.1.2 Systems and equipment shall be selected based
on .a thorough consideration of functional and
operational requirements for the complete operation.
"mphasis shall be placed on reliability and contingency.
j
5.1.1.3 Depending on the complexity and duration of
the operation, and the structure itself, separate studies
may he required to determine the systems and equipment
required for a safe operation, see 2.3. Such studies shall
include normal operations as well as emergency
situations.
5. 1.1.4 The following systems shall be considered
where applicable;
power supply,
fuel supply,
electrical distribution systems,
machine!}' control systems,
5.1.2.2 All back-up systems shall he designed and
fabricated to the same standard as the primary systems.
Back-up systems can when found feasible be an
integrated part of the primary systems.
5.1.2.3 For systems consisting of multiple independent
units back-up may be provided by having a sufficient
number of available spare units available on site.
5.1.2.4 Automatic control systems shall be provided
with a possibility for manual overriding.
5.2.1 General
bilge and ballast systems,
compressed air systems,
fire fighting systems,
5.2.1.1 All vessels shall be in good condition and fit
for the intended operations.
communications systems, and
instrumentation systems for monitoring of;
loads and/or deformations,
environmenta! conditions,
- ballast and stability conditions,
- heel, trim, and draught,
- position (navigation),
- underkeel clearance, and
5.2.1.2 Vessel and barges shall satisfY the hydroslatic
stability requirements given in 4.
-
-
Guidance Note
It is recommended 10 Include a list In the Operation Manual of main
spare parts available on site. It is a/so I:ecommended to assess the
necessity of having repair or service personnel available on site
durfng operetions.
5.2 VESSELS AND BARGES
valve control systems,
),
5.1.2.1 All essential systems, part of systems or
equipment shall have back-up or back-up alternatives.
Necessary time for a change over operations shall be
assessed.
S.2.1.3 All vesselslbarges involved in the operations
shall be inspected prior to the operation to confirm
compliance with design assumptions, validity of
certificates and general condition.
penetration/settlements.
5.1.1.5 Systems shall as far as possible be designed to
be fail safe.
5.2.1.4 Vessels classed by a Classification Society shall
be operated in accordance with requirements from this
Society.
5.1.1.6 Computerised control or data acquisition
systems should be equipped with un-interuplable power
supply system (UPS).
The condition for class as given in "'Appendix to Class"
or similar shall be presented.
5.1.1. 7 All systems shall be tested according 10 3.4.
DEI" NORSKE VERITAS
January 1996
Page 20 of 23
Rules for Marine Operations
Pt.l Ch.2 Planning of Operations
5.2.1.5 For Mobile Offshore Unites the following
annexes (or similar) to the maritime certificates shall be
presented;
Annex I operational limitations,
Annex II resolutions according to which the unit has
heen surveyed, and possible deviations from
these.
5.3 MOORING SYSTEMS
5.3.1 General
5.3.1.1 This sub section applies for design and
verification of mooring of vessel or barges alongside
quays, or for mooring systems combining long and short
lines.
5.2.1.6 Valid recommendations given by the
Classification, Society shall be presented.
5.3.1.2 For verification of offshore and inshore
catinary mooring systems reference is made to Pr.2
CiI.7.
Guidance Note
Modifications to vessellbarge structure or eqUipment may require
approval Irom the Classification Society.
5.2.1.7 · Where severa! tugs or vessels are involved, a
stand by tug to assist or remove vessels in case of black
out, engine failure, etc. should be considered.
5.2.1.8 If allowable deck load is based on "load
charts", limitations IUld conditions for these with respect
to number of loads IUld simultaneousness of loads shall
be clearly stated. Applied dynamic factors, load factors
or material factors shall be specified.
5.3.1.3 For mooring of GBS structures reference is
made to Veritas Marine Operations, Guidelines No.: 1.1
"Mooring and Towage of Gravity Base Structures" ,
November 1989.
5.3.1.4 For certification of offshore mooring wire and
chain refereoce is made to DNV Certification Note 2.5,
"Certification of Ofthore Mooring Steel Wire Rope" and
Certification Note 2.6, "Certification of Offhore
Mooring Chainn .
5.2.1.9 The vessels global and local condition with
respect to corrosion shall be confirmed and considered
strength verifications, see also Pl. 1 ChA Sec. 2. 2. 3.
in
5.3.1.5 Mooring lines shall be in good condition.
5.3.2 ULS conditions
5.2.1.10 Genera! description of vessel systems to be
used shall be presented. Ballast and towing
equipment/systems shall be described in detail if used.
5.2.2 Navigational lights and shapes
5.2.2.1 The vessel or towed object should exibit
) navigational lights and shapes in accordance with IMO
codes and local requlations.
5.2.2.2 Sufficient energy supply for the navigational
lights to last for minimum 1.5 times the expected
duration of the voyage shoul be provided.,
5.2.3 towing vessels
5.2.3.1 Requirements to towing vessels are given in
Pt.2 Ch.2 Sec. 3.3. Requirements to towing equipment
are given in Pt.2 CiI.2 Sec. 3. 1.
5.3.2.1 All relevant combinations of characteristic
loads and directions should be evaluated in the UI..S
case.
5.3.2.2 Characteristic mooring line loads should be
calculated with characteristic loads according to Pt. 1
CiI.3. Sec.2 and Sec.3.
5.3.2.3 Design loads and load cases shold be defined
according to Pr.l ChAo
Guidance Note
Effect of pretension and external loads, e.g. from pulVpush systems,
may be categorized as live loads.
5.3.2.4 Tension in anchors and mooring lines sbould be
calculated based on the design loads, vessel response,
characteristic line and fender sti ffuess, and the local path
of displacement.
5.3.2.5 A dynamic analysis of the system behaviour is
preferable. A quasistatic analyses may be acceptable
upon consideration of natura! frequencies of the system
5.2.4 Barges
5.2.4.1 Requirements to cargo barges and barge
equipment are given in Pt.2 CiI.2 Sec. 3. 1 alld 3.2.
and its individual components.
5.3.2.6 Special considerations shall bc made to the load
distribution in mooring lines for systems with several
short lines arranged in an undetermined pattern.
DET NORSKE VERITAS
Rules for Marine Operations
Ch.2 Plaruting of Operations
January 1996
Page 21 of 23
~\'t.l
I
Guidance Note
5.3.5 Mooring line strength
Quasistatic analysis implies that wind, current, and mean wave drift
(orces are considered as static forces. Forces resulting from wave
induced motions are then added to the sialic forces.
The stiffness characteristics should be determined from recognised
theory.
5.3.5.1 'The mooring line design capacity may be found
by dividing the characteristic strength by the appropriate
material factor, see 5.3.5.4 and 5. 3.5. 6.
The moored structure will take an equilibrium position at which the
restoring force from the mooring system equals the sum of static
forces. The distance from this position to a position corresponding to
zero environmental forces is called the mean quasi static
displacement. Due to the wave Induced forces. the structure will
oscillate around the equilibrium position.
5.3.5.2 'The characteristic strength of mooring lines
may be assumed to be the minimum breaking strength
specified by the fabricator.
The total quasistatic displacement is assumed to be the sum of the
mean quasistatlc displacement and the oscillatory amplityde:
5.3.5.3 Reductions in line capacity due to bending shall
be considered, see also Pt. 2 Ch.5 Sec. 3. 1.
5tom!
= 5me..n + Omotion
If relevant, local dynamics of individual mooring lines should be
included. The line may be excited by the time varying motions ~t the
upper end (found from the dynamic system analysis) and by wave
and current induced vortex shedding.
)
5.3.3 PLS conditions
5.3.3.1 'The mooring system sball be verified for a PLS
case. 'The PLS case sbould be defined as a conditions
witb anyone line broken. Dynamic effects/transient
motion and clearances sball be considered for tbe PLS
case ..
5.3.~.2
Loading conditions c and d, see Pt. 1 CII.4
Table 3.2, should be investigated.
5.3.5.4 'The material factors for certified steel wire
ropes and chains are normally taken as:
1m = 1.5
1m = 1.3
for UlS
for PLS
Guidance Note
Mooring arrangements with planned duration's less than 30 days
and arranged with new certified wire ropes may be verified with a
reduced
matenal factor.
1m= 1.35 (ULS).
Guidance Note
Wire ropes without a certified MBl may be acceptable for mooring
purposes. Design calculations for these systems shall be based on
the fabricators specified MBl and a material faclor: rm~ 1.65 (ULS).
5.3.5.5 If mooring lines are arranged with wire clamps
these shall be installed, and regulariy inspected,
according to fabricators instructions and procedure.
5.3.3.3 Upon failure of one mooring line tbe remaining
system sbould be able to resist expected loads and
displacements until! repaired.
Guidance Note
Special considerations shall be made to the required number of
clamps and possible tensioning and/or control procedure.
Guidance Note
Verification of a PlS may be ommed if lugs are stand by at the
moorfng site, and the system allow the tugs to provide sufficient
thrust at positions and in directions necessary to replace anyone
5.3.5.6 Material factors for synthetic ropes should be
5.3.4 FLS conditions
5.3.5.7 Special attention shall be made to the
possibilities of chaflDg if synthetic fiber ropes are used.
5.3.4.1 For permanent mooring systems of long design
life and with serious failure consequences, fatigue data
should be established for the relevant environment and a
fatigue investigation carried out. The investigation
should be based on the load history of the equipment.
5.3.4.2 For chain cable and steel wire ropes fatigue
data should be based on statements from manufacturers
and available research results.
Guidance Note
For synthetic fibre ropes specifiC fatigue calculations are normally
not required. A condition for this is that the various components will
be replaced at certain intervals. A program for such replacements
should be prepared in each separate case. Besides ordinary
fatigue, the effect of wear, ageing, temperature-rise due to cyclic
IC'<>.-fing, long-term creep and other possible effects should be taken
lccount 'NIlen deciding replacement intervals.
taken as:
1m
1m
= 3.5
= 3.0
forUlS
for PLS
5.3.6 Mooring details
5.3.6.1 Mooring line attachement and equipment such
as;
hollards,
brackets,
mooring rings/lugs, and
fenders.
sball be designed so tbat failures. due to overloading will
not result in damage to the main structure.
5.3.6.2 Submerged mooring brackets shall be design in
such a way that they will Dot cause openings to sea in
case of excessive loading of the bracket.
OET NORSKE VERIT AS
January 1996
Page 22 of 23
Rules for Marine Operations
Pt.l Ch.2 Planning of Operations
5.3.6.3 Design loads for mooring details should be
taken as the characteristic mooring line load multiplied
with load factors, see Pt.} Ch.4.
5.4 'GUIDING AND POSITIONING SYSfEMS
5.3.6.4 Strength verification of 'Wooring line
connections shall comply with requirements in Pt.}
ChAo The characteristic strength shall be documented
either by calculations or certificates. Strength reduction
due to cOlTosion and wear sball be considered.
5.4.1.1 This sub section applies for design and
verification of guiding and positioning systems to be
used for inarine operations.
Guidance Note
Special considerations shall be given to condition or barge bollards
older than 10 years.
5.3.6.5 Onshore boUards without a certificate from a
recognised CertifYing Body should be tested before uSe
to 1. 25 times the characteristic line load.
5.4.1 General
5.4.1.2 Guides and bumpers shall have sufficient
strength and ductility to resist impact and guiding loads
during positioning without causing operational problems
(e.g. excessive positioning tolerances), and without
overloading members of the supporting struct\lre.
Plastic defolTD3tion of guides due to impact loads may be
allowed. After contact between bumpers and guides they
should, in a defolTDed shape, be able to resist loads due
to the environmental conditions during operation, and
5.3.7 Anchors
operational loads from tugger lines, mooring lines etc.
5.3.7.1 The conditions of the seabed should be taken
into account in the selection of the anchor type.
A factor not less than 1.3 between design loads of supporting
structure and guIde/bumper strength Is recommended.
Guidance Note
I
Guidance Note
5.3.7.2 Characteristic anchor forces should be
determined in accordance with 5.3.2 or 5.3.3.
5.3.7.3 The characteristic holding capacity of anchors
should be taken as the conservatively assessed mean
value based on infolTD3tion from tests or theoretical
calculations. The values used should apply to the actual
conditions of the seabed in question.
5.3.7.4 The anchor material coefficient (holding
capacity coefficient) is normally taken as:
Ym = 1.5
Ym = 1.3
Guiding systems are often designed with a primary and secondary
system. The primary system is normally designed to absorb
possible impact energy, and provide guiding onto the secondary
system. The secondary system Is nonnally design to ensure
accurate and controlled positioning of the Object.
5.4.1.3 Guides and bumpers shall after an impact
provide a positive clearance towards neighbouring and
supporting structure, and maintain their functionality.
The possibility and consequences of multiple impacts
shall be considered.
5.4.2 Characteristic loads
for ULS
for PLS
5.4.2.1 Characteristic impact loads for bumpers sho\lld
5.3.7.5 For anchom not designed to cony vertical loads
the length of anchor line should be such that no vertical
force will occur in any loading condition.
5.3.7.6 Direct-embedment anchors of deep penetration
and high holding power/weight ratio may be used
provided the suitability of the anchors is documented in
advance. Alternatively pile anchors may be used.
5.3.7.7 Anchors shall normally be tested to 1.25 times
the characteristic mooring line load. The anchors shall
be tested for at least 15 minutes.
be based on impact and deformation energy
considerations.
5.4.2.2 Realistic impact velocities, impact positions and
defolTDOtlon patterns shall ~e assumed.
,I
I
5.4.2.3 Design loads and load Cases for the impact
phase may, assuming realistic maximum impact
velocities, be established according to requirements for a
PLS ease.
5.4.2.4 Characteristic loads for the guiding and
positioning phase shall be based on environmental
conditions during operation, in addition to operational
loads from tuggerlines, mooring lines etc. Combination
of horizontal and vertical loads during guiding shall be
considered in the design load eases. Realistic friction
coefficients shall be used.
DET NORSKE VERITAS
I
Rules for Marine Operations
Pt.! Ch.2 Planning of Operations
January 1996
Page 23 of 23
5.4.2.5 Design loads and load cases for the gniding and
positioning phase may be established according to
requirements for an ULS case.
5.4.2.6 Characteristic loads for positioning lines
(tugger lines, mooring lines etc.) and attachments
(padeyes, brackets etc.) shall be the expected maximum
line tension. Possible dynamic effects shall be
considered.
5.4.3 Design strength
5.4.3.1 Structural strength of guiding and positioning
systems shall be verified according to Pt.] ChAo
5.4.3.2 Positioning padeyes should be design to behave
., a ductile manner in ease of overloading.
r..
l
[
5.4.3.3 For submerged brackets or padeyes the
requirements in 5.3.6.2 apply.
)
)
DET NORSKE VERITAS
RULES FOR
PLANNING AND EXECUTION OF
MARINE OPERATIONS
PART 1 : GENERAL REQUIREMENrS
()
)
PART 1 CHAPTER. 3
DESIGN LOADS
JANUARY 1996
SECTIONS
)
1. INTRODUCTION ... .. .... ......... . .. .. ...................... ... .... .. . .... ....................................... . ........ ... .... .. 4
2. ENVIRONMENTAL CONDmONS ............................................................................................ 6
3. LOADS AND LOAD EFFECTS ......... ................. .. .... . ..................... .... ......................... :......... .. . 12
()
DET NORSKE VERlTAS
Veritasveien I, N-I322 H0Vik, Norway Tel.: +4767579900, Fax.: +47675799 11
CHANGES IN THE RULES
This is the first issue of the Rules for Planning and
Execution of Marine Operations, decided by the Board
of Det Norske Veritas Classification AlS as of December
1995. These Rules supersedes the June 1985, Standard
for Insurance Warranty Surveys in Marine Operations.
This chapter is valid until superseded by a revised
chapter. Supplements to this chapter will not be issued
except for minor amendments and an updated list of
corrections presented in the introduction hooklet.
Users are advised to check the systematic index in the
introduction booklet to ensure that that the chapter is
These Rules come into force on 1st of January 1996.
current.
..
o
)
)
© Det Nonke Veri18S
Computer Typesetting by Det Non;ke Vento"
Printed in Norway by the Det Norske Veritas January 1996
1.96.600
January 1996
Page 3 aflO
Rules for Marine Operations
Pt.l Ch.3 Design Loads
,
CONTENTS
1.
INTRODUCTION ..........•......•.•.......•.•.... 4
1.1
GENERAL ............ . ............................... 4
1.1.1 Application .................................... 4
1.1.2 Regulations, codes and standards .......... 4
1.2
DEFINITIONS .................................... . .. 4
1.2.1 Terminology ............................ . ...... 4
1.2.2 Symbols .. ...................................... 4
2.
ENVIRONMENTAL CONDITIONS ....•...•.. 6
) 2.1
GENERAL .. . ......................................... 6
2.1.1 Environmental phenomena .................. 6
2.1.2 Characteristic conditions and loads ........ 6
2.1.3 Environmental statistics .................... . 6
2.1.4 Seasonal variations ....... ..... ....... . ... , .... 7
2.1.5 Local e!lvironmental conditions ............ 7
2.2
WIND CONDITIONS ........ . ................ .. ... 7
2.2.1 General .... ., .........•..... .. .................. 7
2.2.2 Characteristic wind velocity ................ 7
2.2.3 Gust wind ...................................... 8
2.3
WAVE CONDITIONS .............................. 8
2.3.1 Design methods ............................... 8
2.3.2 Weather restricted operations ............... 8
2.3 . 3 Unrestricted operations ...................... 8
2.3.4 Design wave method ......................... 9
2.3.5 DeSign spectra method ....................... 9
2.3.6 Swell ............ .. ............................. 10
2.4
CURRENT AND TIDE CONDITIONS ........ 10
2.4.1 Current ........................................ 10
2.4.2 Tide ............................................ 11
3.2.5 Friction effects ........ .. .................... . 13
3.2.6 Tolerances .................................... 14
3.2.7 Model testing ................................. 14
3.3
WAVE LOADS ..................................... 14
3.3.1 First order wave loads ...................... 14
3.3.2 Second order wave loads ................... 14
3.3.3 Analysis of motions .............. .. ......... 14
3.3.4 Wave headings .............................. . 15
3.3.5 Wave periods ................................. 15
3.3.6 Response amplitude operators (RAO) .... 15
3.3.7 Slamming loads .............................. 15
3.3.8 Water on deck .. .... ...... .. .................. 15
3.3.9 Swell ......... .. ................................ 15
3.4
WIND AND CURRENT LOADS ............... 15
3.4.1 Wind load components ...................... 15
3.4.2 Current loads ................................. 15
3.5
STATIC LOADS .................................... 16
3.5.1 Weight estimates ............................. 16
3.5.2 Characteristic weight. ....................... 16
3.5.3 Centre of gravity ............................. 16
3.6
HYDROSTATIC LOADS ......................... 16
3.6.1 Characteristic hydrostatic loads ........... 16
3.7
RESTRAIN LOADS ............................... 16
3.7.1 General ........................................ 16
3.8
ACCIDENTAL LOADS ........................... 17
3.8.1 General ........................................ 17
3.8.2 Vessel collision .............................. 17
3.8.3 Dropped objects .............................. 17
APPENDIX ................................................... 18
Figure List
3.
LOADS AND LOAD EFFECTS ................ 12
3.1
LOAD CATEGORIES ............................. 12
3.1.1 General ........................................ 12
3.1.2 Permanent loads (P) ......................... 12
3. 1.3 Live loads (L) ...................... .. ........ 12
3.1.4 Deformatio!lloads (D) ...................... 12
3.1.5 Environme!ltalloads (E) .................... 12
3.1.6 Accidental loads (A) ........................ 12
3.2
)
Figure 2.1 - Design process ................................. 6
Figure 2.2 - Current stretching method ................... 11
Figure 2.3 - Definition of water levels ................ .. . ll
Table List.
Table 2.1 - Characteristic wind velocities ....... .......... 7
Table 2.2 - Wind profile, U(z,l",...)fU(z,.,t,..w...) ......... 8
LOAD ANALYSIS ................................. 13
3.2.1 General ........................................ 13
3.2.2 Sensitivity studies ........................... 13
3.2.3 DY!lamic effects .............. .. .............. 13
3.2.4 NO!l-linear effects ............................ 13
DEY NORSKE VERITAS
January 1996
Page 4 of20
Rules for Marine Operations
Pt.l Ch.3 Design Loads
1. INTRODUCTION
1.1 GENERAL
Design load: A load or load condition whicb forms
basis for design and design verification.
1.1.1 Application
1.1.1.1 Pf.] Ch.3, Design Loads, applies as reference
for establishing environmental conditions and loads for
marine operations planned and designed according to
requirements and philosophy of these Rules.
1.1.1.2 General recommendation for planning and
preparatipns are given in Pt. 1 Ch.2, and for structural
design in Pt.] Ch.4. Load factors and combination of
loads into design loadcases are described in Pt.] Ch.4.
Gust wind: Average wind speed during a specified time
inteIVaI less than one minute
Long tenn: A period of time where environmental
conditions are non-stationary.
Mean wind velocity: The average wind velocity within
a specified time interval.
Short tenn: A period of time wherein statistical
eovironmental parameters may be assumed stationruy.
Normally 3 or 4 bours.
1.1.1.3 Operation specific requirements and
recommendations are"given in Pt. 2 of these Rules.
1.1.1.4 Conditions for using these Rules are stated in
Pt. 0 Ch.] Sec.I.2.
1.1.2 Regulations, codes and standards
Wave height: The crest to trough height.
1.2.2 Symbols
1.1.2.1 Other complementary recognised codes and
standards may be used.
1.1.2.2 Examples of applicable publications giving
further recommendations are;
)
Significant wave: Four times the standard deviations of
the surface elevation in a short term wave condition
(close to the average of the one third highest waves).
NPD Guidelines conseruing loads and load
effects,
DNV Classification Note 30.5,
DNV Classification Note 30.6,
DNV Classification Note 31.4,
NS 3479, and
Veritas Offsbore Standards, Recommended
Practices.
The list below define symbols used within this chapter:
Ad):
Act :
Ace:
CoG:
c:
D:
d:
d,,:
Fc;IIll:
Fx:
Fy:
F, :
F~:
Fwy :
1.2 DEFlNITIONS
1.2.1 Tenninology
Characteristic condition: A condition whicb, togetber
with load and material factors, render a defined
probability of exceeding structural capacity within a
defined time period.
Characteristic load: A load having a defined
probability of exceeding tbe structural capacity within a
defined time period.
f('I') :
f, :
fa, :
fw{ :
g:
H:
H, :
H.,:
H.... :
HJlUU:
HtIlIU,c :
H, :
h:
DEf NORSKE VERITAS
Current volume, mean wat~r level.
Current volume, top of wnve.
Current volume, bottom of wave.
Center of gravity.
Weibull slope parameter for wind.
See Sec. 2.3.3.
See Sec. 2.3.3.
Operation period in days.
Collision load.
Force comp. , X direction.
Force comp. , Y direction.
Force Comp. , Z direction.
Wind force comp., X direction.
Wind force comp., Y direction.
Directional function.
See Sec. ;2.3.3.
See Sec. 2.3.3.
Weatber forecast uncertainty factor.
Acceleration of gravity.
Wave height.
Significant wave height.
Characteristic wave height.
Characteristic significant wave heigbt.
Max. wave beight.
Max. cbaracteristic wave beight.
WeibuU scale parameter for waves.
Water depth.
Rules for Marine Operations
Pt.1 Ch.3 Design Loads
January 1996
Page 5 of20
bo :
Reference water depth.
j :
Weibull slope parameter for wave.
k:
See Sec. 2.3.3.
N :
Number of occurrences.
S(OJ :)
Wave spectrum.
S(OJ.'I'): Directional wave spectrum.
STF :
Stprm factor.
T:
Exposure period.
TA :
Period with stationary wind conditions.
T. :
Wave spectrum peak period.
Tw :
Wave period.
Tz, :
Mean zero up-cros~ing period.
t,.= :
Average period for wind.
t,. m~ : Reference average period for wind 10 min.
t.i(z,..t,..m~ : Reference wind velocity.
Uo .....(z.t,.~) : Characteristic max. wind.
U(z.t,....,): ~ax. mean wind within a period T A .
) U. :
Weibull scale parameter for wind.
v:
Current velocity.
VdJ:
Current velocity, mean water level.
Vel :
Current velocity, top of wave.
va:
Cun"ent velocity, botlom of wave
Vtido :
Tide generated current velocity.
v""" :
Wind generated current velocity.
W:
Loads due to self weight.
z,.,.,. : Max. wave amplitude.
z:
Height or depth.
z,. :
Reference height = 10m.
a. :
Phillip.' constant.
y:
Wave spectrum peakness parameter.
'I' :
Wave spreading angle.
1.. :
Wave length.
IT :
Spectral width parameter.
OJ :
Angular wave frequency.
OJ. :
Angular spectral peak frequency.
=
)
DET NORSKE VERITAS
Rules for Marine Operations
Pt.1 Ch.3 Design Loads
January 1996
Page 6 or20
2.
E~ONMENTALCONDnaONS
2.1 GENERAL
The design process involving;
2.1.1 Environmental phenomena
2.1.1.1 Environmental conditions are natural
phenom~na which
contribute to structural stress and
strain, impose operationallimitations/restrictions or
navigational considerations. Phenomena of general
importance are;
characteristic conditions,
characteristic loads, and
design loads
is illustrated in Figure 2.1.
Figure 2.1 - Design process
wind,
waves and
curreJ;lts.
Analysis &
Calculations
Phenomena which may be of importance are;
tide,
soil conditions,
ice and snow.
load
Factors
earthquake,
Design &
Verification
temperature,
fouling,
visibility/fog and
heavy rain.
2.1.3 Environmental statistics
2.1.2 Characteristic conditions and loads
2.1.3.1 .Environmental phenomena may be described by
2.1.2.1 Characteristic conditions are conditions with a
defined probability of exceedance, within a defined
period of time.
2.1.2.2 Characteristic conditions and loads combined
)
with load and material factors as specified by these Rules
complies with the overall objectives as stated in Pr.O
CIl.1.
Guidance Note
Note that these Rules adopt an approach alternatiVe to the traditional
return period design philosophy although With the same safety
philosophy. A return period design will have (dependent of duration)
a variatlng probability of failure, while these Rules aim at a constant
probability of failure per operation.
With a return period approach an operation would have the same
characteristic condition both for a three days and a three months
planned duration. A three months period would however expose the
object for a longer period, with a corresponding higher probability or
failure compared to the tree days operation.
I
2.1.2.3 Characteristic conditions and loads combined
with load and material factors according to PI. 1 CII.4
sball form the basis for design and design verification.
statistical distributions and variables. Statistical data
should as far as possible be used to establish
characteristic environmental conditions. The statistical
description should revcal the extreme conditions for
shorl and long term cases.
2.1.3.2 Statistical data used as basis for establishing
characteristic environmental criteria must cover a
sufficiently long period of time period. For
meteorological and oceanographic data a minimum of
three to four years of data collection is recommended:
2.1.3.3 The environmental design data should be
representative for the geographical area or site.
2.1.3.4 If statistical envirorunental data are assumed to
follow a two parameter Weibull distribution, the
regression analysis should be performed with emphasise
on a correct representation of the extreme values .
Guidance Note
Regression analysis of two parameter Weibull distributions are
recommended based on the 30 % highest data points , Le.
P(x>X)=O.3.
OET NORSKE VERITAS
Rules for Marine Operations
Pt.1 Ch.3 Design Loads
January 1996
Page 7 or 20
2.1.4 Seasonal variations
2.2.2.2 For unrestricted operations the characteristic
wind velocity may be calculated according to Eq. 2-2
2.1.4.1 Seasonal variations may be taken into account.
Uo
T
!.
U,,,,,,(z.to~) = 1.22In(-:r:-·IO')c .
2.1.4.2 Characteristic environmental conditions
considering seasonal variations shall be based on
statistical data for the actual operation month(s). and the
preceding and succeeding month.
Eq.2-2
where
U,,mu(z.t,....,) = Characteristic max. wind speed.
= Exposure time.
TA
= Period for which wind conditions are assumed
stationllI}' (usually 3 hours) or max. wind
observation period.
T
2.1.5 Local envirpnmentaJ conditions
2.1.5.1 Loca1 environmental conditions. not reflected
by statistical data; shall be investigated.
(
)
Characteristic wind velocities less than the 1 year return
wind is not recommend~ for un'restricted operations.
Such effects may be;
special tide variations,
special swell or wave conditions,
2.2.2.3 Simplified characteristic wind velocities may be
taken according to Table 2. 1. Wind velocities exceeding
41m1sec. t,.~= IOmin. z= 10m need normally not be
considered on the Norwegian continental shelf.
current variations, and
local wind variations/conditions.
Guidance Note
Local harbour authorities, pilots etc, may be sources (or such
information.
10 year return
2.2 WIND CONDITIONS
100 year return
2.2.1 General
2.2.1.1 Wind velocity varies with time and height
above tbe sea surface.
'lQ/\
)
2.2.2.4 For weather restricted operations characteristic
wind velocities less than IOmlsec are generally not
recommended. Requirements to ratio between operation
The averaged wind velocity over a defined period is
referred to as mean wind.
aod design wind is given in Pt. 1 Ch.2 Sec.]. 1.
Guidance Note
Forecasted wind is normally given at z=1 Om reference height and
tmnn=10 min. mean wind.
2.2.2.5 The wind velocity profile may be related to a
2.2.1.2 The characteristic mean wind period shall
correspond to the systems response periods.
reference height (z,) and mean time period (1,..m..J
according to Eq. 2-3. see also Table 2.2.
.
U(z,t~)= U(Z"t,,mom{1+0137~:') -O.047ht,:J]
Guidance Note.
The ,following periods are meant as illustrative examples;
- local plate field
3
(sec.]
1
(minute]
- Mooring with ·short· lines
_ catenary mooring of vessels
10
{mlnutes1
• catenary mooring of GBS
60
(minutes]
2.2.2 Characteristic wind velocity
2.2.2.1 The statistical behaviour of maximum mean
Eq.2-3
where
z
z,
t,.=
=
=
=
=
~.mcaa
U(z.t,....,) =
U(z,.I,..m..J =
wind velocities. U~(z.t,....). within a "short term"
period ('fA) may be described by a Weibull distribution;
-( ...~-f
Pr(U) = 1- e
Uo
Eq.2-1
PrCU) = Cumulative probability ofU~(z.t,....,).
= U~(z.t,....). max. mean wind speed.
U
Uo = Weibull scale parameter.
= Weibull slope parameter.
c
DET NORSKE VERITAS
Height above sea surface.
Reference height 10 [mI.
Averaging time for design.
Reference averaging time 10 [minutes].
Average wind velocity.
Reference wind speed.
January 1996
Rules for Marine Operations
Pt. 1 Ch.3 Design Loads
Page 8 of20
Table 2.2 - Wind profile,
U(z,t".~")fU(z..t.
)
--c;- . _
l'~ :;)
given in Pt. 1 Ch.2 Sec. 3. 1.
Guidance Note
-'·f :
.~ .
2.3.2.2 Requirements to ratios between operation
criteria and significant characteristic wave height are
T
_
0.93
0.79
0.69
0.60
1.15
1.01
0.91
0.82
1.25
1.11
1.00
0.92
1.34
1.20
1.10
1.01
2.3.2.3 Characteristic maximum wav~ beight for
weather restricted operations sbould be estimated
according to Eq. 2-4.
1.47
1.33
1.22
1.14
H_ = STF*H,
1.56
1.42
1.32
1.23
:
Significant wave heights less than 2m are not recommended. for
open sea operations.
Eq.2-4
where
)
2.2.3 Gust wind
STF = 2.0 for operation reference periods up to 72
hours.
2.2.3.1 For elements or systems sensitive to wind
oscillations (e.g. where dynamics or fatigue may be
governing for the design) the sbort and long term wind
2.3.3 Unrestricted operations
variations should be considered.
2.3.3.1 Characteristic wave conditions for unrestricted
operations shall be based on long term statistical data.
2.2.3.2 The wind variations may be described by a
wind spectrum according to NPD, Guidelines for Loads
and Load Effects.
2.3.3.2 Long tenn variations of waves may be
described by a set of sea states, each characterised by tbe
2.3 WAVE CONDITIONS
2.3.3.3 Characteristic significant wave beight, H,.o may
be taken according to 2.3.3.5. Corresponding maximum
wave height, ~o, maybe taken according to 2,3.3.6.
2.3.1 Design methods
2.3.1.1 Wave conditions are defined by characteristic
wave height, He, or the significant wave height, H.,c, and
corresponding periods.
)
2.3.1.2 Wave conditions for design may be described
either by a deterministic design wave method, see 2.3.4,
or by a stochastic method see 2.3.5.
2.3.1.3 Witb the deterministic metbod tbe design sea
slates are represent by regular periodic waves
cbaracterised by wave length (or period), wave beight
and possible shape parameters.
2.3.1.4 With the stocbastic method tbe design sea states
are represent by wave energy spectra characterised by
parameters sucb as H, and T, or Tp.
wave spectrum parameter e.g. H., Tz or oc, T p' y.
Characteristic values sball be based on tbe defined
operation reference period, see Pt. 1 Ch.2 Sec. 3. 1.
Periods less than 3 days shall not be used.
Gui~ance Note
The Hl!lU,c corresponds to a 10% probability or exceedance (or
individual wave heights. Characteristic wave conditions defined
according to alternative methods should be based on the 10%
rraclile of the extreme wave heIght distribution of individual waves for
the antiCipated operation duration.
2.3.3.4 In the absence of site specific wave data tbe
Weibull parameters in table Al (Appendix) may be used.
Guidance Note
For operationsllransports .passing through several area, the extreme
value distribution may be based on an accumulated distribution of
Individual wave heights conSidering (he exposure period in the
individual area. A simplified approach would be to estimate Hmu.c
based on exposure in the worst area (or the whole operation period.
2.3 .2 Weather restricted operations
2.3.2.1 Characteristic wave conditions for weatber
restricted operations, i.e. operations with wave heights
(andlor periods) selected independent of statistical data,
see also Pt.} Ch.2 Sec. 3. 1.2, should be as described by
2.3.5.
DET NORSKE VERIT AS
Rules for Marine Operations
Pt.l Ch.3 Design Loads
January 1996
Page 9 oflO
2.3.3.5 Characteristic significant wave height for the
exposure period may be taken as
H. =Hl(2~/1)
o
It"
J
2.3.4.2 The following wave periods should be
considered for the characteristic wave height H" (H-.o
in metres and T in seconds).
=(45H max ., )"2
T
Eq.2-5
(
H
1/2
0
45H m ... o )
S T S 20
where
< H .....,
H=H~."
. Eq.2-7
f, = In(R . N) + (d - I) In(in(R . N»)
2.3.5 Design spectra melhod
2.3.5.1 The design spectm method i. based on
calculation of motion and load responses in sea states
characterised by a wave spectrum.
r(d - ~) = Gamma function, see appendix A
)
=
d
1.S-(1I2j)
Wei bull parameters for the probability
function of the observed significant wave
heights, see also 2.3.3.4.
H, andj =
N
14400 d,. where d,. is the number of days
within the deSign operation period.
=
2.3.3.6 Maximum characteristic wave height, H_o,
for a defined exposure period may be taken as
Hmaz,o= 1.8
where
Zmax = D ( fOJ )
c- 2.52 . H~::2 S
T. S 13
0 .52
(
)0.5
2.52 · H,.,
ST. S 30· H •.D
~(~r(tr
S(lo)
Reference is made to 2.3.3.5 for definitions of symbols.
lO-'eX{-%(:pf +e-t.~:'r 10(1)]
Cil
= Angular waVe frequency, Cil=2n!Tw•
Tw
Wave period.
= Angular spectml peak frequency Cilp=21!rrp.
A.cceleration of gravity.
Genemlised Phillips' constant,
(5116)*(H,2lO :lg1*(I-U.287ln(y»
Spectml wi~th parameter.
= 0.07 if",,,;
= 0.09 if'" > Cilp
Peakness parameter.
"'p
g
a
a
2.3.4 Design wave method
2.3.4.1 For most practical purposes the kinematics of
regular deterministic waves may be described the
following theories:
= Water depth.
= Ilg2
Eq.2-9
2+j
where
H•., >5.6 [m]
Eq.2-8
where
k=~
hI;\. ,,; 0.1
Solitary wave theory.
0.1 < hI;\.,,; 0.3 Stokes' 5th order wave theory.
hi;\, > 0.3 .
Linear wave theory.
H..,S 5.6 [m]
2.3.5.3 Wave spectra defined by the Jonswap or the
Pierson Moskowitz spectrum are most frequently used.
The spectral density function is;
"k
f o., = In(IO · R . N) + (d - l)ln(ln(IO . R · N))
h
;\.
2.3.5.2 For the design sea spectra method the following
periods should be considered (H..o shall be given in
metres, Tz in seconds).
z,...
Eq.2-6
D =
Characteristic significant and maximum responses are
identified by investigating a range of T. periods
according to 2.:1.5.2. The wave spectrum may be taken
according to 2.3.5.3.
(J
Y
=
=
=
=
=
lOp
=
The Pierson Moskowitz spectrum appears fory = 1.0.
The relation between T, and Tp may be taken according
to Eq. 2-10.
T
tEL
• =TPVu-:;r
= Wave length.
Eq.2-IO
DEI' NORSKE VERIfAS
J~uary
1'~el0
Rules for Marine Operations
1996
of20
Pt.1 Ch.3 Design Loads
2.3 .5.4 The Pierson Moskowitz spectrum is generally
r=<>mmended for open. deep waters ( > 150m) and fully
2.3.6.2 Swell type waves may be assumed regular in
de"...loped seas. The Jonswap spectrum is recommended
for fetch limited. growing seas and in shallow waters.
independent from wind generated waves.
Fo. a general Jonswap spectrum the r parameter may.
unless specific data are available be taken as (f, in
sec.<lnds and H, in metres);
2.3.6.3 Characteristic height for swell type waves may
for
y=5
r
(S.75)S:'~)
.JH.
=e
for
for
be taken as the 10 year retnm value. Critical swell
periods should be identified and considered in the design
verification.
Tz
..JH:
<2.7
T
z
2.7 S; /U
2.4 CURRENT AND TIDE CONDITIONS
S;
3.7
"H,
y =1
period and height. and may normally also be assumed
~ > 3.7
"H,
2.3.5.5 A directional short crested wave spectrum. see
&J-
2-11. may be applied based on non-directional
spe<:tra.
2.4.1 Current
2.4.1.1 Characteristic current velocity shall be based on
local statistical $!a and experiences. Unless more
detailed evalnations of current velocity are made the
characteristic current shall be the taken as the 10 year
retum value.
o
2.4.1.2 Variations in current velocity due to tide sball
Eq.2-11
Guidance Note
where
=
'P
be considered for insho.re operations.
Angle between direction of elementary wave
trains and the main direction of the short
crested
wav~ sy~tem.
S(CD.'P) = Directional short crested wave power density
spectrum.
f(q»
= Directional function.
j f(q»dq>
=
1
q mlD
Eq.2-12
10 absence of more reliable data the following directional
function may be applied for H, between 2 and 10m;
f( q>}= (0.116+0.37* H~.s) COSH, (q»
f(<p} = 0
2.4.1.3 Effects of simultaneous occurrence of current
aod waves sball be considered.
Guidance Note
Allhough the tidal current velocity can be measured. and the wind
gehemted .current velocity can be calculated, the resultIng current In
the extreme storm condition Is a rather uncertain quantity, Note that
errors in the estimation of current velocity are often consIdered to
represent one of the most critical uncertainties in the loa,d analysis.
Energy conservation requires that the directional
function fulfils &J. 2-12;
"'mal:
Significant local vanations In current velocity due to tide may occur.
If site specific data are not aVClilable current variations shou1d be
monitored prior 10 and during Ihe operation, see Pt.1 Ch.2 SeC.3.
2.4.1.4 10 open areas the characteristic wind-generated
current velocities at still water level may J if statistical
data are not available. be taken as;
v"",, = O.OIS*U(z.t"..,J
Eq.2-14
-1<12 '" 'P '" 1<12
elsewhere
Eq.2-13
Directional short crestness should not be considered for
significant wave heights exceeding 10m.
where
U(z.t"..,J is the wind velocity according to 2.2.
z
= 10 [m)
t,,_
= 1 [hr]
2.3 .6 Swell
2.3.6.1 Swell are long period waves generated outside
the geographical area of interest. Swell type waves
should be considered for operations sensitive to long
period motion or loads.
DEl' NORSKE VERITAS
(
Rules for Marine Operations
Pt.1 Ch.3 Design Loads
January 1996
Page 11 of20
2.4.1.5 The current profile should be specially
considered for each project. Alternatively the current
profile may be taken as
v(z) = V.d.(Z)
+ v"",,(z)
2.4.2 Tide
2.4:2.1 The astronomical tidal range is defined as the
range between the highest astronomical tide (HA1) and
the lowest astronomical tide (LA1), see Figure 2.3.
Eq.2-15
where
V tide (Z)
V wind (Z)
=
. (h+Z)"7
-z-
=
z,;o
V Ihle
V wind
(
h0
+
h0
z)
-h" > z
v(z)
z
)
Vtide
v"""
h
h"
= Total current velocity at level z.
= Distance from still water level, positive
upwards.
= Tidal current velocity at still water level.
= Wind generated current velocity at still water
level.
= Water depth to still water level (taken
positive)
= Reference depth for wind generated current, ho
=50m
2.4.2.2 Mean water level (MWL) is defined as the
mean level between the highest astronomical tide and the
lowest astronomical tide.
2.4.2.3 Storm surge includes wind induced and
atmospheric pressure induced effects. Variations due to
storm surge shall be considered.
2.4.2.4 Characteristic water levels shall be taken as
expected astronomical tide variations plus/minus storm
surge effects. Both a maximum and minimum
characteristic water level shall be defined for operations
sensitive to tidal variations, see Figure 2.3.
Fi
e 2.3 - Definition of water levels
2.4.1.6 It is normally assumed that waves and current
are coincident in direction.
2.4.1.7 Variation in current profile with variation in
water depth due to wave action shall be accounted for.
Variations in the current profile may for regular waves,
and as a simplified approach, be considered by stretching
the current profile vertically. The current velocity at
any proportion of the instantaneous depth is kept
constant, see Figure 2.2. By this method the surface
MN. 1MlmlE\R
current component shall remain constant.
Figure 2.2 - Current stretching .method
v"
v,,
V,1
CURRENT PROFILE
CURRENT PROFILE STRETCHING
NO WAVE
( VCIJ
(Ac1
>
Vel
Aco
:.
Vc2 )
Ac2)
)
DET NORSKE VERITAS
January 1996
Rules for Marine Operations
Pt.1 Ch.3 Design Loads
Page U of 20
3. LOADS AND LOAD EFFECTS
3.1 LOAD CATEGORIES
3.1.4 Defonnation loads (D)
3.1.1 (;eneral
3.1.4.1 Deformation loads are associated with
deformations. Such loads may be;
3.1.1.1 Loads and load effects shall he categorised into
the foUowing groups;
l'erman""t Loads " P,
Live Loads - L,
Deformation Loads - D,
Envirol)Illental Loads - E, and
Accidental Loads - A.
installation or set down tolerances,
structural restraints between structures,
differential settlements, and
temperature.
3.1.4.2 Characteristic deformation loads shall be
~um or minimum values resulting from
characteristic environmental conditions.
3.1.2 Permanent loads (P)
3.1.5 Environmental loads (E)
3.1.2.1 Permanent loads are static loads which will not
be moved or removed during the phase considered.
Such load may be;
weight of structures,
weight of.permanent ballast and equipment that
can not be removed,
external/internal hydrostatic pressure of
3.1.5.1 All loads caused by environmental phenomena
shall be categorised as environmental loads. Such loads
may be;
wind,
waves,
current,
storm surge,
permanent nature, and
tide, and
ice.
buoyancy (permanent part).
3.1.2.2 Characteristic permanent loads shall be based
on reliable estimates of weight, weight control system or
weighted weight, see also 3.5.
3.1.5.2 Loads due to the gravity components in plan
parallel or perpendicular to deck, caused by motions due
to wind and waves of a floating object, shall be
categorised as environmental loads.
3.1.3 Live loads (L)
3.1.5.3 Characteristic environmental loads shall be
based on characteristic environmental conditions as
specified in Sec.2.
3.1.3.1 Live loads are loads that can be moved,
removed or added. Such loads may be;
opemtion of cranes.,
loads from alongside vessels,
differential ballasting,
operational impact loads, and
stored materials, equipment or liquids.
3.1.6 Accidental loads (A)
3.1.3.2 Characteristic live loads shall be specified with
maximum and minimum values, both values may be
necessary to consider.
3.1.6.1 Accidental loads are loads associated with
exceptional or unexpected events or conditions. Such
loads may be;
collisions from vessels,
dropped objects,
loss of hydrostatic stability,
flooding, and
loss of internal pressure.
3.1.6.2 Characteristic accidental loads shall be based on
realistic accidental scenarios.
Realistic accidental scenarios may be identified by
Hazop techniques, see Pt. 1 Ch.2 Sec. 2.
DEI" NORSKE VERITAS
Rules for Marine Operations
Pt. i Ch.3 Design Loads
January 1996
Page 13 of20
3.2 LOAD ANALYSIS
3.2.3 Dynamic effects
3.2.3.1 Dynamic loads and load effects shall be
3.2.1 General
3.2.1.1 All loads and load effects which during the
marine operation may influence operational procedure,
investigated. Dynamic load effects may be caused by
oscillatory wave forces, wind loadS (gusts), vortex
shedding in air or water, or slamming loads.
design or the dimensioning of structures shall be
analysised and considered in planning and preparation
for marine operations.
3.2.3.2 Dynamic loading effects shall be investigated
3.2.2 Sensitivity st"dies
3.2.3.3 Special considerations should be made to the
by recognised methods, realistic assumptions of natural
period, damping, material properties etc.
possibilities of dynamic amplification.
3.2.2.1 Parametric sensitivity studies should be
performed if any load or operational parameters
significantly affect the design or the selection of method
and equipment.
If the result of the study indicates that the operational
safety is critically dependent on any parameters,
increased reliability shan be obtained for the design
solution e.g. by use of conservative characteristic values.
Guidance Note
The objectives with a sensitivity study are to reveal If minor changes
of input parameters critically or unexpectedly affect the design. .
3.2.2.2 Consequences of unexpected conditions and
loads w.r.t. structural capacity and failure modes should
be investigated. Emphasis shall be put on possible nonlinear load effects.
Guidance Note
Examples of unexpected conditions may be unexpected
deformations and load distributions, unexpected weights and C.o.G
pOSitions, unexpected buoyancy and centre of buoyancy etc.
3.2.2.3 Consequences of malfunctioning equipment and
erroneous operation of equipment or systems shall be
evaluated.
3.2.3.4 Both fatigue and ultimate stress or deflection
may be critical for the design.
3.2.4 Non-linear effects
3.2.4.1 Non-linear effects shall be considered in cases
where these significantly influence the load estimates.
Typical non-linear effects are;
material ncm-linearities,
geometrical non-linearities,
damping effects,
non linear effects due to combination of load
components or response components, and
wave elevation effects.
3.2.4,2 Non linear load effects due to combination of
environmental conditions should be evaluated.
Guidance Note
The quadratic Increase In drag loads due combination of wave
particle velocity and current velocity illustrate such effect.
3.2.5 Friction effects
Guidance Note
Examples of malrunctionlng equipment may be leaking valves,
valves impossible to close, pipeline fracture, unexpected deformation
pattern of load distribution elements.
Examples of erroneous operation of equipment may b~
opening/closing of wrong ballast valve.
3.2.5.1 Effect of friction shall be considered in the
3.2.2.4 The variations of input parameters shall be
necessary to considered in the design calculations.
within realistic limits. Too small variations shall be
avoided.
3.2.5.3 The friction coefficient range shall be defined
3.2.2.5 Consequences of parameters outside specified
according to recognised industry standards or tests, see
also Pt.2 Ch.l Sec.2.2.5.
or expected values or ranges may be categorised as a
PLS condition.
3.2.5.4 Consequences of friction coefficients outside
Single unplanned or unexpected events, see 3.2.2.2 alld
3.2.2.3, shall not lead to a progressive failure situation.
the established range shall be evaluated, and if found
severe the range shall be extended, see also 3.2.2.
design verification.
3.2.5.2 A friction coefficient range, i.e. both a
maximum and a J;D.inimum friction coefficient may
be
Simultaneous variations of several input parameters
outside the specified design value or range does not be
3.2.5.5 Vibrations, variating or uncertain surface
considered.
condition etc. affecting the friction shall be considered.
DET NORSKE VERITAS
January 1996
Rules for Marine Operations
Pt.l Ch.3 Design Loads
Page 14 or20
3.2.5.6 Restraint effects caused by combination of
friction and global deflections shall be considered.
3.2.6 Tolerances
3.2.6.1 Loads caused by operational or fabrication
tolerances exceeding tolerances stated in the design
standards/codes sh..n be considered. Typical examples
may be;
. set down tolerances (load out, positioning),
.himming tolerances, and
uncertain deformation (in load distributing
material).
3.2.6.2 Characteristic loads .ball be based on specified
maximum or minimum values.
3.3.1.4 Wave slamming loads, see 3.3.7,
hydrodynamic loads and hydrostatic loads on members
protruding over the barge side shall be considered. The
effect of such loads 00 motion characteristics and on
seafasteuing /grillage shall be accounted for.
3.3.2 Second order wave loads
3.3.2.1 Second order wave drift forces may be
important for design of certain marine operations. The
effect of second order drift forces .hall be considered for
these cases.
Guidance Note
Drift are particular important for large volume structures, design of
moorings and positioning systems, towing resistance estimates, etc.
Q
3.3.2.2 Second order wave loads may be assumed to
consist of;.
3.2.7 Modeltesting
mean wave drift forces, and
3.2.7.1 Testing to detennine motions or loads may be
required. Reference is also made to 3.3.3.1
3.2.7.2 Adequate and reliable model test data sbould be
used to verify/correlate tbeoretically calculated
envirnnmentalloads. This is particularly relevant for
geometrically complex structures and for new design or
operational concepts.
.low varying wave drift forces.
o
3.3.2.3 Long period responses exitated by slow drift
force. sball be investigated.
3.3.3 Analysis of motions
3.3.3.1 Motions of floating objects sball be determined
for the relevant environmental conditions and loads.
3.2.7.3 The law of similarity sball be carefully
considered in order to obtain a representative test result.
Effects that may influence the measured quantity, and
that can not be represented in the model test sball be
identified and consequences of these effects sbould be
evaluated.
3.3 WAVE LOADS
3.3.1 First nrder wave loads
3.3.1.1 Wave loads .hould be estimated according to a
deterministic or stochastic design method. A wave
period range according to 2.3.4 or 2.3.5 should be
investigated.
Guidance Note
If any responses are found dimensioning for T~ < 2.52H"c0.52 the
response should be checked In these areas with H,=O.17T1.' .(12
3.3.1.2 Wave loads sball be determined by use of
methods applicable for tbe location and operation, taking
into account the type of structure, size, shape and
response characteristics.
3.3.1.3 Effects of wave elevation shall be evaluated,
and if necessary included in the design verification.
Testing of models or full scale structures may be carried
out where relevance of theoretical approaches are
uncertain, or where the design is particularly sensitive
for motions.
Estimation of motions from model testing or by
theoretical calculation has associated advantages and
disadvantages. The two approaches are generally to be
considered as complimentary rather than as alternatives.
3.3.3.2 It i. recommended to correlate theoretical
calculations against relevant model test data (if available)
in cases where strong non-linear behaviour may be
expected. Such cases may be when;
overhanging cargo is being occasionally
submerged, or
there are large changes in the water plane area
with draught.
3.3.3.3 The analytic models should be checked witb
respect to sensitivity to input parameters, see 3.2.2.
3.3.3.4 Recognised and well proven six degrees of
freedom linear or linearized computer programs,
uiilising the strip theory or 3D sink source techniques
are generally recommended. Special considerations sball
be made to the non linear damping effects. The effect of
forward speed shall be evaluated.
DET NORSKE VERITAS
Q
Rules for Marine Operations
Pt.l Ch.3 Design Loads
January 1996
PagelS of 20
Guidance Note
Cases where conservatively estimated motions significanlly
influence the design are recommended analysed with a strip or 3D
sink source program. This generally applies for transport of objects
weighing more than 1000 lannes.
3.3.4 Wave headings
3.3.4.1 The full range of wave headings shall be
considered. Spacing between analysed wave headings
should not exceed 45 degrees. If wave short crestedness
is considered analysed wave headings should not exceed
30 degrees.
3.3.5 Wave periods
3.3.5.1 A wave period range with corresponding wave
heigbts, see 2.3 ·shall be considered when evalnnting
characteristic motions and accelerations.
3.3.8 Water on deck
3.3.8.1 The possibilities, and effects of extensive
amounts of water on deck due to waves shall be
considered. Both structural and stability (weight and
free surface) effects shall be investigated.
3.3.9 Swell
,
3.3.9.1 Loads and motion effects of swell shall be
considered. Swell may be governing for towing
operations designed for small irregular waves (H. less
than 4 to Sm) as the relative importance of swell e!fects
increase.
3.4 WIND AND CURRENT LOADS
3.4.1 Wind load components
3.3.6 Response amplitude operators (RAO)
3.3.6.1 RAO's for the basic six degrees of freedom
may be utilised to establish RAO's for displacements,
3.4.1.1 Wind loads shall be calculated based on
characteristic wind speed, see 2.2, and recognised
methods.
velocities, accelerations, and reaction forces (for a body
fixed co-ordinate system). These RAO's may be used
for calculation of significant and maximum responses.
3.3.6.2 When combining different responses, the phase
angle between the different components may be
3.4.1.2 Wind induced loads shall be based on projected
area. Total wind load shall consid~r both lateral and
parallel load components.
Possibility and magnitude of lift effects shall be
considered.
considered.
3.3.6.3 The gravity component shall be considered
when determining the RAO's for inertia loads (e.g.
3.4.1.3 The gravity components due to wind heeling
shall be considered.
transverse accelerations).
Guidance Note
I{[
3.3.6.4 Inertia loads due to motion should be calculated
for all six degrees of freedom.
Guidance Note
This include also an evaluation of inertia effects from roll and pitch.
These effects should as a minimum be quantified, and the effect
evaluated. This Is particularly relevant for barge transports with
large roll motions.
DNV Classification Note 30.5, ~Environmental Conditions and
Environmental Loads· give further information with respect to shape
coefficlenls, effects of angulare wind and 3D effects.
3.4.2 Current loads
3.4.2.1 Current loads shall be calculated based on
characteristic current velocity, see 2.4, and recognised
methods.
3.3.7 Slamming loads
3.3.7.1 Elements in the splash zone or overhanging the
outer borders of the floating body shall be investigated
w.r.t. possibility and effect of slamming loads.
3.4.2.2 Current induced drag loads shall be calculated
considering both current and wave particle velocity.
3.4.2.3 Increased current velocitieslloads due to
shallow waters or narrow passages shall be considered.
3.3.7.2 Shock pressures on surfaces in the splash zone,
caused by breaking waves, shall be investigated.
DET NORSKE VERITAS
January 1996
Page 16 of20
Rules for Marine Operations
Pt.l Ch.3 Design Loads
3.5 STATIC LOADS
3.5.2.5 The weight control system sbould be employed
until the installation is completed. Weight estimates
sball be corrected for remaining work.
3.5.1 Weight estimates
3.5.1.1 Weight and position of centre of gravity sbould
preferably be determined by weighing. If weighing is
not feasible, the weight and ceotre of gravity sbould be
calculated on basis of accurately specified weights and
volumes, anellor weigbed or estimated weights of parts
of tbe object.
3.5.1.2 Weighing equipment witb inaccuracy higher
tban 3 % is not recommended. If weighing equipment
wilb inaccuracy higher tban 3 % is used Ibe cbaracteristic
weight sbould be adjusted, e.g. by application of an
inaccuracy factor. This factor sbould be defined
considering tbe weighing arrangement and procedures.
3.5.2 Characteristic weight
3.5.2.1 Cbaracteristic weight sball be taken as one of
tbe following;
a)
weighed weight,
b)
weight according to a detailed weigbt control
system; or
c)
estimated weight.
For cbaracteristic weights based on weighings after 90 %
completion, an inaccuracy factor of 1.0 is acceptable, see
also 3.5.2.2 and 3.5.2.3. For cbaracteristic weights
based on c), a weight inaccuracy factor of minimum 1.1
sboul" be applied.
Guidance Note
For designs having critical details in tensIon, possible minimum
weights should also be considered in the design/engineering
phases, I.e. characteristic weight divided by the inaccuracy factor.
3.5.2.2 A weigbt control system that continuously
forecast final weight and CoG poition, is recommended.
The system sbould include all components and consider
weight uncertainties. It is recommended to establisb and
maintain an overall weight inaccuracy fktor based on
corresponding factor for eacb object/component The
factors sbould be cbanged (reduced) during Ibe
design/fabrication as found appropriate.
Guidance Note
Note that normal weighing operations only idenUfy the CoG position
in a horizontal plan. Inaccuracies in vertical CoG position should
hence be specially considered ror operations sensitive to vertical
CoG position.
3.5.3 Centre of gravity
3.5.3.1 Inaccuracy in CoG position sball be considered
in Ibe design Iqads. To allow for CoG inaccuracies a
CoG envelope or box is recommended. The size of Ibe
envelopelbox sbould reflect Ibe operational and
structors! sensitivity to CoG variations. Furtber sbould
object shape, size, type of operation, control possibilities
(weighing, transfer operations) etc., be considered wben
establishing tbe CoG box.
Guidance Note
For early design phases loa small envelope/box should be avoided.
Box sizes less than 1x1x1 m shOUld be aVoided.
Guidance Note
For operations with a linear relation between CoG shifts and
loadslload effects, or operalions less sensitive to CoG shifts,
inaccuracy in eslimated CoG may be account!,!d for by an
inaccuracy factor. This facler should nennally not be taken less
than 1.05.
3.6 HYDROSTATIC LOADS
3.6.1 Characteristic hydrostatic loads
3.6.1.1 Hydrostatic loads can generally be categorised
as permanent loads (P).
Cbaracteristic loads should be based on maximum andlor
minimum expected values.
3.6.1.2 The buoyancy of Ibe object sbould be
determined on Ibe basis of an accurate geometric model.
The position of tbe center of buoyancy sbould be
establisbed accordingly.
3.7 RESTRAIN LOADS
3.5.2.3 Weight and CoG position estimates based on
weight control systems sbould normally be
confirmed!calibrated towards one or more weighings.
3.5.2.4 A detailed weighing procedure, including
equipment specifications, sbould be made. The
weighing sbould normally be repeated at least three
3.7.1 General
3.7.1.1 Loads and motions due to interaction between
structures deflecting in environmental condition (e.g.
waves, temperature, redistribution of ballast etc.) sball
be considered, see also Pt. 1 ell.4 Sec. 2. 2.4.
times.
DEl' NORSKE VERITAS
QI
OJ
Rules for Marine Operations
Pt.l Ch.3 Design Loads
January 1996
Page 17 of 20
3.7.1.2 Horizontal restraint loads may typically occur
3.8.2.2 The behaviour of Ibe vessels or structures
wilb a statically undetermined seafastening arrangement.
during the impact. and Ibus the distribution of impact
energy between kinetic rotation and translation and
deformation energy. should be considered by dynamic
Guidance Note
Horizontal restraints may typically occur for "pitch- seafastening
arrangements with stoppers at both ·ends~. Restraint loads may
normally be Ignored for "roll- stopper arrangements If the stoppers
are arranged on both sides of the module and each stopper supports
load in one direction only. If the stoppem support load In both
directions the effect of restraints should be considered.
It Is generally recommended to: as far as possible, avoid horizontal
restraint loads through proven design of seafastening.
3.8.2.3 Bolb local effects (deformation. damage. etc.)
Guidance Note
Guidance Note
DNV. Rules (or Classification of Mobile Offshore Units, Pl3 Ch.1
In order to obtain a statically determined system, ~fastenlng ~nd
grillages are often arranged with sliding surfaces . .If sliding surfaces
are used, any effects caused by the sliding should be considered,
i.e. possible clashes, rucation of "'ow friction" pads etc.
3.7.1.3 Vertical restraint loads. due to interaction
equilibrium or energy considerations.
and global load effects (acceleration. global stress. etc.)
shall be considered.
Sec.4and PNV. Veritas Offshore Standards, RP 0205 (May 1981)
-Impact loads from Boats" give further guidance for estimating
Impact loads.
3.8.3 Dropped objects
between independent deflecting structures. caused by
)
environmental condition (e.g. waves, temperature
3.8.3.1 Loads caused by dropped objects may be
ballasting) shall be considered.
relevant for some PLS load cases. Characteristic loads
due 10 dropped object should be based on possible object
weight and IIllIXimum fall height in lb. actual position.
3.7.1.4 Vertical restraint loads may typically occur due
to bending and torsion deflections of barges.
3.8.3.2 For objects falling Ibrough water a 20 deg.
Restraint loads in tension details (uplift stoppen;.
connections to barge decks) should be specially
dispersion angle should be assumed.
considered.
Guidance Note
Vertical restraint etrects may typically be considered for transports of
objects on standard barges with three or more supports over the
length o( the barge. For objects supported on totally four supports
on typical cargo barges restraint effects due to torsion may normally
be ignored.
Guidance Note
Global moments for calculation of global denections does not be
taken greater than wave bending moments according to DNV, Rules
for Classification of Ships Pt.3 Ch.1 SecA.
\
\
) 3.8 ACCIDENTAL LOADS
3.8.1 General
3.8.1.1 Accidental loads should be defined bosed on
relevant accidental cases and contingency situations.
Accidental cases and contingency situations may be
defined or excluded based on results from HAZOP's or
risk evaluations/assessments. see also Pt.l Ch.2 Sec. 2.3.
3.8.2 Vessel collision
3.8.2.1 Cbaracteristic collision loads shall be estimated
from energy considerations. Estimates of collision
energy should be based on reasonable assumptions of
possible collision scenarios, velocities, directions, ship
or object type. size. mass and added mass. Estimates of
deformation energy should be based on most likely
impact points and probable deformation pallems.
DET NORSKE VERITAS
Rules for Marine Operations
Pt.1 Ch.3 Design Loads
January 1996
Page 18 of20
APPENDIX A
Figure At - Area Definition.
...
"
".
n•
..
.
EO
"
'10
.
,
".
~~
"
""
.,"
.
20
•
..
..
~.
20
"
..
'"
I
..
I
~'
EO
'"
".
n.
..
"
.
20
20
"
"
I
"
~1I"
I
".
I;J
n.
".
101
~
.a~2
~
'".
Nautical zones for estimation of long teno wave distribution parameters.
o
)
DET NORSKE VERITAS
Rules for Marine Operations
Pt.l Ch.3 Design Loads
&1:-:: . . . ,- .
.
. j,: '
'-" ' .
" :' ~
•i<: .
I
".'N : f· :"'.:."'/:
';'
. .
. .
. . ''''''
i "' .:." :',: : '\;. ·;X.·:"':i: . . .,., '. .
.
2.33
1.96
2.74
2.84
1.76
2.76
3.39
3.47
3.56
2.45
53 ·
54
55
56
57
.58
59
60
61
62
1.26
1.56
1.64
1.46
1.50
1.56
1.41
1.14
1.35
1.48
2.19
3.31
3.18
2.62
3 .09
3.42
2.77
1.66
2.48
3.15
1.69
1.72
1.39
1.48
1.61
1.30
1.30
1.28
1.38
1.56
2.97
2:29
2.23
2.95
2.90
1.81
1.76
1.81
2.31
3.14
63
64
65
66
67
68
69
70
7-1
72
73
74
75
76
77
78
79
80
81
82
1.79
1.47
1.66
J..70
2.05
1.82
1.53
1.24
1.37
1.42
2.62
1.81
2.17
2.46
2.74
2.32
1.66
1.23
1.74
2.36
47
48
49
50
1.50
1.41
1.78
2.17
2.07
1.44
1.78
2.20
2.13
1.28
51
52
1.44
1.50
II
12
13
14
15
16
17
18
19
20
)
i!!: ci 'C! '. """ ·'.''' "' ,'t,/, .','':,.'' ' ;:';\;
1.33
1.34
1.35
1.53
1.59
1.45
1.75
1.57
1.61
1.37
2
3
4
5
6
7
8
9
10
j,
..
,~
January 1996
Page 19 of20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
!
!
,
,
.
.
1.93'
2.19
2.56
2.45
1.96
2.18
2 .19
2 .08
1.76
1.39
1.82
1.39
1.70
2.16
1.90
2 .15
2.21
2.16
1.89
1.84
1.69
1.93
1.83
2.40
2.17
1.85
2.02
1.93
2.10
1.73
1.88
234
2.02
2.33
2.43
2.42
2.23
2 .32
1.79
2.44
2.26
1.69
1.67
1.77
1.83
1.70
1.53
1.70
1.71
1.94
2.80
2.23
2.69
2.86
3.04
2.60
2.18
2.54
2.83
2.84
83
84
85
86
87
88
89
90
91
92
1.83
2.10
1.94
1.54
1.40
1.75
1.45
1.59
1.68
1.71
2.60
2.92
3.32
2.91
2.43
3.35
3.02
3.35
3.54
3.42
.2.47
2.32
2.78
2 .83
2.60
1.76
2.30
2.55
2.50
2.05
93
94
95
96
97
98
99
100
101
102
1.45
1.69
1.93
1.47
1.63
1.70
1.77
1.54
1.57
1.60
2.66
3.89
3.71
' 2.65
1.78
2.14
103
104
1.58
1.57
~
DET NORSKE VERITAS
,
3.61
3.53
4.07
3.76
3.21
3.08
..
'":,,!....:: .
Rules for Marine Operations
Pt.l Ch.3 Design Loads
January 1996
Page 20 of 20
Table A2 - Gamma
Function Values
.. .....
':"<
, '.
)
"
"
"
,'.
f, '
.. ,-
.. ..~~!;:'~:
"e'"
,
~
" ..
: ..
(";'
:,
.'
.: ".;.:.
0.50
0.52
1.7725
1.7058
1.02
1.04
0.9888
0 .9784
.:a.-~ ,',
1.54
1.56
0.54
1.6448
1.06
0.9687
1.58
0.56
1.5886
1.08
0.9597
1.60
0.8935
0.58
1.5369
1.10
0.9514
1.62
0.8959
0.60
1.4892
1.12
0.9436
1.64
0.8986
0.62
1.4450
1.14
0.9364
1.66
0.9017
0.64
1.4lJ41
1.16
0.9298
1.68
0.9050
0.66
1.3662
1.18
0.9237
1.70
0.9086
0 .68
L3309
1.20
0 .9182
1.72
0.9126
0 :70
1.2981
1.22
0.9131
1.74
0.9168
0.72
1.2675
1.24
0.9085
1.76
0.9214
0.74
1.2390
1.26
0.9044
1.78
0.9262
0 .76
L2123
1.28
0.9007
1.80
0.93\4
0.78
1.1875
1.30
0.8975
1.82
0.9368
0 .80
1.1642
1.32
0 .8946
1.84
0.9426
0.82
1.1425
1.34
0.8922
1.86
0.9487
0.84
1.1=
1.36
0.8902
1.88
0.9551
0.86
1.1031
1.38
0 .8885
1.90
0 .9618
0.88
1.0853
lAO
0 .8873
1.92
0.9688
0 .90
1.0686
1.42
0.8864
1.94
0 .9761
0.92
1.0530
1.44
0.8858
1.96
0.9837
0.94
1.0384
1.46
0.8856
1.98
0.9917
0.96
1.0247
1.48
0.8857
2.00
1.0000
0.98
1.0119
1.50
0.8862
1.00
1.0000
1.52
0.8870
.,I;~ Q.- ·I: _ ~'.•
,
, ." Cla)';·"",·; , 1>'--'" ,,1, .
:"
' ;, ',
,
:;:
"
:
0.8882
0.8896
0.8914
a
u
)
u
DET NORSKE VERITAS
RULES FOR
PLANNING AND EXECUTION OF
MARINE OPERATIONS
PART 1 : GENERAL REQUIREMENTS
()
)
PART 1 CHAPTER 4
STRUCTURAL DESIGN
JANUAR 1996
SECTIONS
\
)
I . INTRODUCTION .. ... .. .... ..... .. .... ....... ... ... ... .. ... .. .. . .. .. ......... . ... .. .. .. .... ... . .. .. .... .. ...... ... .. ... . ......... .. 4
2. DESIGN PRINCIPLES .. . .. ... .... .. ............ .. . .. ..... . .. .. .. .. .. .... .... ..... . ...... .... .. ......... .... .............. : .. .. ... . 6
3. DESIGN METHODS .... .. .. ...... ......... .... .. .... .. .. ... .... .. ....... . .. . .. ..... .... .... ...... ....... . ....... .... ...... ........ 9
4. RESISTANCE AND MATERIALS .... .. .......... .. .. .. .... .. . .......... .. .............. ...... .... .. .... ... .... .. .. .. ......... 13
,)
DET NORSKE VERITAS
Veritasveien I, N·1322 Hevilc, Norway Tel.: +4767579900, Pax.: +47675799 II
CHANGES IN THE RULES
This is the first issue of the Rules for Planning and
Execution of Marine Operations, decided by the Board
ofDet Norske Veritas Classification AlS as ofDece\Dber
1995. These Rules supersedes the June 1985, Standard
for Insurance Warranty Surveys in Marine Operations.
These Rules cO\De into force on 1st of January 1996.
This chapter is valid until superseded by • revised
chapter. Supplements to this chapter will not be issued
except for minor amendments and an updsted list of
corrections presented in the introduction booklet.
Users are advised to check the systematic index in the
introduction booklet to ensure that that the chapter is
current.
)
(/)
)
)
@ Del Norske Verita&
Computer Typcseuing by Det Norske Veritas
Printed in Norway by the Det Norske Veritas 1anuary 1996
n
Januar 1996
Rules for Marine Operations
Pt.l Ch.4 Structural Design
Page 3 of 15
CONTENTS
1.
INTRODUCTION ......................•........•.• 4
4.
RESISTANCE AND MATERIALS ............ 13
1.1
GENERAL ................................•.. · ........ 4
1.1.1 Application ...... •....•........... ............. 4
1.1.2 Regnlations, codes and standards ....... ... 4
4.1
1.2
DEFlNTTIONS ............................... ........ 4
1.2.1 Terminology ............. ...................... 4
1.2.2 Symbols ........................................ 5
S1RUCTURAL RESISTANCE .................. 13
4.1.1 General ........................................ 13
4. 1.2 Characteristic resistance .................... 13
4.1.3 Materiru. coefficients - ULS ................ 13
4.1.4 Material coefficient - PLS .................. 14
4.1.5 Material coefficient - SLS .................. 14
4. 1.6 Material coefficient - FLS .. ; ............... 14
4.2
()
2.
DESIGN PRINCIPLES ............................ 6
)
2.1
DESIGN CONSIDERATIONS .................... 6
2.1.1 General ................... ...................... 6
2.1.2 Structural details ........ .. .... .. .............. 6
2.1.3 Inspection ........ . ............................. 6
2.1.4 Existing structures ............................ 6
2.1.5 Protection against accidental damage ...... 6
MATERlALS AND FABRICATION ........... 14
4.2.1 General ....·.................................... 14
4.2.2 Structural categories ......................... 14
4.2.3 Material quality .............................. 14
4.2.4 Fabrication .................................... 14
4.2.5 Non destructive examination .......... . .... 15
2.2
\,
)
LOAD CAS):JS ........... . ........................ ... 7
2.2.1 Load combinations ...........................,' 7
2.2.2 Sensitivity analysis .... .. ..................... 7
2.2.3 Loads due to motions and wind ............ 7
2.2.4 Restraint and inertia loads ................. .. 7
2.2.5 Loads due to irregnlar waves and swell ... 7
2.3
DESIGN ANALYSIS AND CRITERIA .......... 8
2.3.1 General ......................................... 8
2.3.2 Failure modes ....... .......... , ............... 8
3.
DESIGN VERIFICATION ....................... 9
3.1
VERIFICATION METIlODS ..................... 9
3. 1. 1 Probabilistic methods ........................ 9
3.1.2 Partial coefficient method ................... 9
3.1.3 Pennissible stress method ........ .. ......... 9
3.2
STRENGTII VERIFICATION ................... 10
3.2.1 General ........................................ 10
3.2.2 Limit state definition .......... .. ... ......... 10
3.2.3 Design approach ............................. 10
3.2.4 Acceptance criteria ...................... ..... 10
3.2.5 Ultimate limit state - ULS .................. 11
3.2.6 Progressive collapse limit state - PLS .... 11
3.2.7 Fatigne limit state - FLS .................... 11
3.2.8 Serviceability limit state - SLS ............ 12
3.3
TESTING ................................. .. .. .. ..... 12
3.3.1 General ........................................ 12
3.3.2 Model testing .................. ............... 12
3.3.3 Full scale testing and monitoring ......... 12
Figure List
Fignre 3-1 - Comparing safety levels .................... 9
Table List
Table 3.1 Table 3.2 Table 3.3 Table 4.1 -
DET NORSKE VERITAS
Load factors for ULS.. _..................... l1
Load factors for PLS ........................ 11
Cumulative damage ratios .................. 1l
Material coefficients for members in
compressiop. .. . ...................... . ......... 13
Januar 1996
Page 4 of 15
Rules for Marine Operations
Pt.l Ch.4 StructuraI Design
1. INTRODUCTION
1.1 GENERAL
1.2 DEFINITIONS
1.1.1 Application
1.2.1 Tenninology'
1.1.1.1 The intention of Pt.l Ch.4, Structural Design is
to give requirements and guidelines for design and
verification of structures involved in marine operations.
1.1.1.2 General recommendation for planning and
preparations of marine operations are given in Pt.l
Ch.2, and for establishing environmental conditions and
loads in Pr. l Ch. 3.
1.1.1.3 Operation specific requirements and
recommendations ~e given in Pt. 2 of these Rules.
1.1.1.4 Conditions for using these Rules are stated in
Pt.D Ch. l Sec.l.2.
1.2.1.1 General definitions of terms are included in
Pt. D Ch.l. Terms considered to be of special
importance for this chapter are repeated below.
Characteristic load: The value of a randomly variable
load that bas an agreed probability of exceedance under
actual conditions within an agreed time period.
Characteristic resistance : The value of resistance that
bas ,an agreed probability of exceedance.
Characreristic strength: The material strength,
determined by tests, tbat bas an agreed probability of
exceedance.
.
Design life: The period of time from commencement of
construction to condemnation of the structure.
1.1.2 Regulations, codes and standards
1.1.2.1 This cbapter does not specifY detailed
requirements for design and fabrication. Accordingly
this cbapter shall be used together witb other recognised
codes and standards for design and fabrication.
1.1.2.2 Examples of acceptable publications describing
additional requirements to design and fabrication are;
NPD - Guidelines on Design and Analysis of
Steel Structures,
NS3472 - NOIwegian Steel Standard, and
API - RP-2A-LRFD; "Recommended Practice for
Planning, Designing and Construction Fixed
Offsbore Platforms - Load and Resistance Factor
Design.
DNV - Rules for Classification of Fixed Offsbore
Installations,
DNV - Rules for Classification of Mobile
Offshore Units,
DNV - Rules for Classification of Steel Ships,
DNV - Supporting documents to tbe Rules as
Appendices, Guidelines, Classification Notes, and
Certification Notes.
1.1.2.3 Combining requirements in different codes
sbould be done with due consideration to tbe desired
safety level.
Design load: Load used in the design of a structure,
i.e. characteristic load mUltiplied by the load coefficient.
Design load qrect: The load effects calculated on the
basis of the design load.
Design resistance: The resistance to be used in the
safety evaluation of a structure or part of a structure,
i.e., cbaracteristic resistance divided by tbe material
coefficient.
.
Design strellgtl!: The material strengtb to be used in the
determination of the design resistance of a structure or
part of a structure, i.e., cbaracteristic strength divided
by tbe material coefficient.
Limit state: A state in whicb a structure ceases to fulfil
tbe function, or to satisfY the conditions, for whicb it
was designed.
wad: Any action causing stress or stmin in the
structure.
Load cotfficient: Coefficient by whicb the
cbaracteristic load is mUltiplied to obtain the design
load.
Load qrect: Effect of load on tbe structure, sucb as
stresses and stress resultants (internal forces and
moments), strain, deflections and deformations,
Operatioll reference period : The time period to be used
in establishing the characteristic value of a random
parameter used as the basis for the design.
DET NORSKE VERITAS
Rules for Marine Operations
Pt.I Ch.4 Structural Design
Januar 1996
Page 5 of 15
Recognised code or slandard: National or international,
code or standard, which is recognised by the majorily of
professional people and institutions in the marine and
offshore industry.
1.2.2 Symbols
The list below define tbe symbols used in this chapter:
A:
D:
E:
F:
Fe:
F ti :
Fd:
Fde£ :
)
F; :
Fi.m~ :
Fi,amp:
Fmot :
F",,:
FWJ;.:
F",,:
Fl.:
Fy:
F%.:
FLS :
f" :
fer :
fd:
fc: :
fy:
L:
P:
PLS:
q:
qo :
R:
R"
R,,:
s:
Sd:
SLS :
ULS:
W:
Yr :
Yo :
1m:
'Ym,uh :
"-:
Accidental load, see PI.1 Cil.3 Sec.3.1.6.
Deformation load, see PI.} Cil.3 Sec. 3. 1.'1.
Environmental load, see PI. 1 Ch.3 Sec. 3. 1.5.
Lo.ad . .
Characteristic load.
Characteristic load.
Design load.
Maximum loads due to deflections.
Load.
Cbaracteristic static load components.
Amplitude of dynamic load components.
Maximum inertia loads due to motion.
Total design load.
Wind force in x direction.
Wind force in y direction.
Inertia force in x direction.
Inertia force in y direction.
Inertia force in z direction.
Fatigue limit state.
Characteristic strength.
Critical buckling stress.
Design strength.
Critical elastic huckling stress.
Yield strength.
Live load, see PI.] Cil.3 Sec. 3. 1.3.
Permanent load.
Progressive collapse limit state.
Usage factor.
Permissible usage factor.
Resistance.
Design resistance.
Characteristic resistance.
Loading effect.
Design load effect.
Serviceability limit state.
Ultimate limit state.
Load due to self weight (vectors).
Load coefficient.
Load coefficient.
Material coefficient.
Material coefficient for ULS.
Reduced slenderness.
)
DET NORSKE VERIT AS
Januar 1996
()
Rules for Marine Operations
Pt.1 Ch.4 Structural Design
Page 6 of 15
2. DESIGN PRINCIPLES
2.1 DESIGN CONSIDERATIONS
2.1.3 Inspection
2.1.1 General
2.1.3.1 To the extent relevant or practicable, access for
inspection, maintenance, and repair shall be provided.
2.1.1. 1 The overall desigo shall be performed with due
consideration to the execution of marine operations.
2.1.3.2 instrumentation which gives information on the
performance may be used as a silpplement to other
2.1.1.2 The desigo shall be such that acceptable safety
is achieved during the marlne operations. Acceptable
safety shall nonnally be provided against;
inspection.
) =
loss and damage of property,
loss of human lives or injury of human health,
and
pollution or other damage of the environment.
2.1.4 Existingstructures
2.1.4.1 Strength calculations for marine operations will
often include verification of existing steel structures
including barges. Possible reduction in desigo capacity
due to e.g.;
2.1.1.3 Structures shall be able to resist local damages
without a total collapse.
corrosion
damages, and
modifications not shown on drawings
2.1.1.4 Structural components and details should be so
shaped that the structure as far as possible will behave in
a ductile manner. Connections should be desigoed with
smooth transitions and proper alignment of elements.
Stress concentrations should as far as possible be
avoided.
Guidance Note:
A structure or a structural element, may be brittle even If it is made
of ductile materials e.g. when there are sudden changes in section
properties.
)
2.1.1.5 Simple load and stress patterns shall be aimed
for in the desigo.
2.1.1.6 Structures shall preferably not be desigoed to
rely on compressed air such as internal over pressure in
buoyant members or underbase air cushions to obtain
sufficient safety against structural failure. This may,
however, be exempted from in 1ipecial
ekes upon
need to be considered.
2.1.4.2 Existing structures should normally be
inspected in order to assess possible reductions in the
design capacity.
Guidance Note
In case inspections 9f eXisting structures in barges are not carried
out, a reduction of the plate thickness indicated on barge drawings
of 0.2 mm per year from the barge was new is recommendeli. This
indicated value is assumed to account for corrosion on bo~h sides of
the plate For hew barges with a proper corrosion protection
system, e.g. painting or coating, no thickness reduction need to be
considered for the first five year of the barge lire.
2.1.5 Protection ngainst accidental damage
2.1.5.1 The structure shall be protected against
accidental damage by the following two principles:
Reduction of damage probability.
Reduction of damage consequences.
thorough consideration of the systems involved,
including back·up systems, redundancy, failure
consequences, duration of the operation, etc.
2.1.2 Structural details
2.1.2.1 Transmission of tensile stresses through the
thickness of rolled steel elements (plates, beams etc.)
should as far as possible be avoided.
2.1.5.2 Pipes, equipment, structures etc. which in a
damaged condition involves risk of accidental flooding,
explosion, fire or pollution, shall be proteCted to
minimise the risk of accidental damage. The protection
may be established by providing a sheltered location, by
local strengthening of the structure, or by appropriate
fender systems.
2.1.2.2 Structural details above the waterline shall be
so arranged that water will not be trapped in the
structure if this may cause damages such as e.g. rupture
due to freezing of the water.
DET NORSKE VERIT AS
Rules for Marine Operations
Pt.1 Ch.4 Structural Design
Jaouar 1996
Page 7 of 15
2.2.3 Loads due to motions aod wind
2.2 LOAD CASES
2.2.1 Load combinations
2.2.1.1 Loads and load effects according to Pt.1 Ch.3
shall be combined to load cases applicable and physically
feasible, for the actual structures and type of operation.
2.2.1.2 All possible load cases which during the marine
operation may influence the dimensioning or feasibility
of the marine operation shall be considered in the design
and design verification.
2.2.1.3 Characteristic loads may be combined taking
into account their simultaneous occurrence.
)
2.2.3.1 In lieu of a refined analysis the worst possible
combination of the individual resP9nses for the same
heading, including components from the self weight and
wind, shall be combined, i.e.
Sd = S(±{Fx+F..,J, ±(Fy+Fwy),+(W±FJ)
Eq.2-2
where
Sd :
Design load or load effect.
S( ) :
Response/load effect function.
F"Fy,Fx : Inertia forces (vectors), in x, y and z
directions including relevant loadfactors and
gravity components.
F~,Fwy:
2.2.1.4 Characteristic static load components and
characteristic dynamic load components which are
statistically independent may be combined according to
Eq.2-1.
W:
Wind forces (vectors), ill x and y directions
including relevantloadfactors. The horizontal
load components due to wind illduced beel or
trim shall be included.
Load due to self weight (vectorS).
Guidance Note:
Dynamic load components shall in this context be
restricted to loads with periods less than 10 minutes.
Dynamic loads with periods greater than 10 minutes
shall be added as mean values
n
2
L Fi,amp
i= l
Eq.2-1
where
Wind loads based on the one hour mean wind will normally be
acceptable in the above la_
ad combination.
2.2.3.2 Where transfer functions for motions are
available these may be combined to a transfer function
for the actiJal response or load effect. The phasing
between the different components should be considered.
Significant and extreme values sbould be estimated
according to Pt. ] Ch.3 Sec. 2. 3.
Guidance Note
Characteristic static load components.
This method require care(ul evaluatipns of Ule responses to be
analysed. All responses which will be governing for th~ design shall
be considered.
Amplitude of dynamic load components.
2.2.1.5 Correlated dynamic load components shall be
added as vectors, unless statistical data of simultaneous
2.2.4 Restraint and inertia loads
occurrence are available ,.
Guidance Note
Note that load components due to first order motions are considered
to be correlated. Combination of these components are described in
2.2.3.
2.2.4.1 Combination of restraint loads due to barge
defleCting ill waves, see Pt. 1 Ch.3 Sec. 3. 7, and inertia
loads due to barge motion may be taken according to Eq.
2-3.
2.2.2 Sensitivity analysis
Eq.2-3
2.2.2.1 Defining loadcases shall include parametric
sensitivity analyses whenever found relevant. The
extent of such analysis sball comply with Pt. 1 CiI.3
Sec. 3. 2. 2.
where
F",,: Total design load.
Fd,,: Maximum loads due to deflections.
Fm~ : Maximum inertia loads due to motions.
2.2.5 Loads due to irregUlar waves and swell
2.2.5. 1 Combinations of load and load effects from
irregular waves and swell shall be combined. These
loads and load effects may normally be combined as
statistically independent.
DEl' NORSKE VERITAS
Januar 1996
Page 8 of IS
Rules for Marine Operations
Pt.1 Ch.4 Structural Design
2.3.2.3 Local modes of failure may be;
2.3 DESIGN ANALYSIS AND CRITERIA
plastic overloading (yield),
buckling,
2.3.1 General
fracture,
2.3.1.1 The analytic models used for evaluation of
responses, structural behaviour and resistance must be
relevant considering the design philosophy, type of
operation and possible failure modes. They .hould
satisfactory simulate the behaviour of the structures,
large deflections, and
excessive vibration.
its
supports, and the environment.
2.3,1.2 Design analyses should generally include the
following stepa:
Determination of cbaracteristic load., see Pt. 1
CII.3.
)
Determination of relevant load cases, see 2.2.
Calculation of load effects.
Determination of structural resistance, see 4.1.
Determination of safety, which depends on the
ratio between loading effect and structural
resistance, and on the uncertainties of these
quantities.
2.3.1.3 Adequate safety is obtained when the steps in
2.3.1.2 satisfy certain requirements and criteria. The
detailed requirements and criteria depend on the design
method used.
2.3.1.4 Design method. are;
probabilistic methods,
the partial coefficient method, and
the permissible stress method.
These methods are explained in sections 3.1,3.1.2 and
3.1.3.
2.3.2 Failure modes
2.3.2.1 All relevant failure modes shall be investigated.
The relevant failure modes may be grouped according to
their nature, either as global (total system) or local
(individual members) modes of failure.
2.3.2.2 Global modes of failure may be;
overturning,
sliding,
lift-off,
loss of hydrostatic or hydrodynamic stability,
sinking,
settlement, and
free drift.
}
DET Noruarn VERITAS
Rules for Marine Operations
Pt.1 ChA Structural Design
lanuar 1996
Page 9 of 15
3. DESIGN VERIFICATION
3;1.204 The method is particularly suitable for nonlinear problems since safety coefficients are included
both on the load side and on the material side.
3.1 VERIFICATION METHODS
3.1.1 Probabilistic methods
3.1.1.1 The evaluation of safety may be based on
probabilistic methods. In these methods calculations are
made to deterJDine the probability of failure mnking use
of a probabilistic description of the joint occurrence of
the relevant parameters involv ed, tak:i.p.g into account the
true nature of the failure domain. All relevant failure
modes shall be considered, see 2.3.2.
3.1.1.2 All p"",!"eters which are essential in the
analysis of an actual failure criterion shall be described
as stochastic variables. Such parameters are load.,9 and
materials' strength, geometry imperfections,
J
uncertainties in the failure criterion model nsed, etc.
3.1.1.3 Probabilistic analyses may be directly used as a
design method or it may' b'e used in combination with
another method. Particular benefit of this method may
be ac'hieved for the detennination of partial coefficients,
see 3.1.2, to be used in dYDamic problems, associated
with the determination of design loads for floating and
compliant structures.
3.1.3 Permissible stress metllOd
3.1.3.1 By this method the target safety is obtained by
calibrating an inverted safety factor which is applied to
the characteristic value of the structural resistance. The
inverted safety factor is normally referred to as the
permissible usage factor.
3.1.3.2 Generally the factors should be defined such
that the safety level will he equal or greater than
obtained with the partial coefficient method.
Guidance Note:
The common used basic usage factors in ULS are 0.6 considering P
and L loads only and O.B when E loads are included as well.
The graphs in Figur.e 3-1 compare the safety level (I.e. characteristic
load/characteristic reslstance) applying the partial ~oefficlent method
and the permissible stress method. Usage factors are as indicated
above,1m = 1.15, equal chaiclcterlstlc load,S and loadfa~ors
according to Table 3.1 are assumed.
Fi ure 3-1 - .Com arin
safe
levels
'.1
--
3.1.1.4 In probabilistic design analyses the design
criteria are normally that calculated probabilities of
failures shall not exceed specified target probabilities,
see also Pt. a Ch.I Sec. 1.
II
V
I
t---
t---
'"
'.2
3.1.1.5 The target probability of failure for an
individual structural element shall never be higher than
that the target value for the total system will be met.
...•
•o
10
zo
30
~o
~o
sn
70
80
90
100 ,
% ParlTlQ"ltlll Laods, (100'(P+l)/(P+l+£))
1--
PI>'I. C. .... Ihod
f.m. Sirus IL
3.1.2 Partial coefficient method
3.1.2.1 In the partial coefficient method the tar.get
safety is obtained by mUltiplying characteristic values
(reference values) of loads and structural resistance by
calibrated coefficients such as load and material
coefficients.
3.1.2.2 How partial coefficients are applied to obtain
design values for load and structural resistance and to
ensure adequate safety is explained in 3.2.4
The graphs in Agure 3-1 Indicate that the safety level obtained by
applying an 1/3 allowable stress Increase, i.e. from OJ~ to 0.8, due to
the presence of E loads, are not generally acceptable. An acceptable
safety level may be oblalned by;
increase the characteristic E loads, or
decrease the basic usage factor,
For non linear problems (e, g, buckling) an additional reduction in the
permissible usage factor may be applicable in order to ensure an
acceptable safety level.
3.1.2.3 Characteristic values of loads and structural
resistance parameters are defined in Pt. 1 Ch.3 Sec.3 and
4.1 respectively.
DEl NORSKE VERITAS
Januar 1996
Page 10 of 15
Rules for Marine Operations
Pt.t Ch.4 Structural Design
3.2 STRENGTH VERIFICATION
3.2.4 Acceptance criteria
3.2.1 General
3.2.1.1 These Rules recommend the partial coefficient
method for verification of structural strength. Load and
material factors specified in this sub·section are
according to the principles of the partial coefficient
method.
3.2.1.2 Usage factors for the permissible stress method
are not defined in these Rules. Permissible usage factors
are to be agreed in each case.
3.2.4.1 The fonnal requirement tbat the structure may
reacb but not exceed n defined limit state when subjected
to design loads, is satisfied wben the design load effect,
Sd' does not exceed the design resistance, R., for all
possible failure modes i.e.;
Eq.3·1
The equation Sd
= R. defines the limit state.
3.2.4.2 A design load effect is a load effect (sucb as
stress or stress resultant) due to a design load i.e.:
Sd = S(FJ
3.2.2 Limit state definition
Eq.3·2
3.2.2.1 A limit state is commonly defined as a state in
which the structure ceases to fulfil the function, or to
satisf'y the conditions, for which it was designed.
3.2.2.2 The following limit state spall be considered in
the strength verification;
The Ultimate Limit States (ULS), related to the
maximum load canying capacity (yielding limit
state, buckling limit state, etc.)
The Fatigue Limit State (FLS), related to the
where
S:
loading effect
Fd: design load
S(FJ : S-function of Fd
!
)
3.2.4.3 A design load is obtained by multiplying the
characteristic load by a load coefficient i.e.:
Fd = Yr' F.
Eq.3·3
where
Yr:
load coefficient
effect of repeated loading.
Fe :
characteristic load
The Progressive Collapse Limit States (PLS),
related to maximum load canying capacity under
the assumption that local damage is unavoidable,
or that certain parts of the structure have been
damaged or removed (see also ULS).
3.2.4.4 A design resistance is obtained by dividing the
characteristic resistance by a material coefficient, i.e.:
capacity of the structure to resist accumulated
Eq.3.4
where
The Serviceability Limit States (SLS), related to
limits regarding structural behaviour under
Rc :
specified conditions of service or treatment
'Ym :
(deflection limit state, vibration limit state, limit
states related to human limits, etc.)
characteristic resistance
material coefficient
3.2.4.5 In practical design Eq. 3·] may take various
forms. If R,. can be defined by one single quantity, Eq.
3· ] may be written as;
3.2.3 Design approach
3.2.3,1 The format of the partial coefficient method
implies that strength verification of structures or
structural element involves the following steps:
Identif'y all relevant limit states/failure·modes.
For each limit state an!! failure mode, determine
tbe design loads and conditions.
For eacb limit state and failure mode, determine
the design load effects.
For eacb limit state and failure mode, determine
the design resistance.
Ensure adequate safety by proving that the design
loads or effects does not exceed the design
resislUflce.
Eq.3·5
3.2.4.6 If both Sd and R. cannot be defined by single
quantities, Eq. 3·] may be written as;
Eq.3·6
Above function describes a combination of the fractions
S..IR., through S.JR.", by intemction. A typical
example of this case is the buckling of a plate subjected
to various stress components, for which the structural
resistance may be defined separately for eacb component
acting alone.
DIlT NORSKE VERITAS
Rules for Marine Operations
Pt.1 Ch.4 Structural Design
Januar 1996
Page 11 of 15
3.2.5 Ultimate limit state - ULS
3.2.5.1 For the ultimate limit states (ULS) the two load
conditions a and b as given in the Table 3.1 below sball
be considered.
3.2.6.2 The evaluation of safety against progressive
collapse (PLS) sball be carried out in tbe following two
steps:
1)
this cbeck loading condition c applies, see Table
3.3 (loads of type E may be ignored).
Table 3.1 - Load factors for ULS
~;~~~~ci~~.H': .<.: :~;:::.. . :.· :.:. L~:~~~~:~~;6~f~~'i~~ >~':~\::.~;:~~:':
~:a~.... ... .~; \ :-;:
1.3 I 1.3 I 1.0 I 0.7 I .NA
'1> .,.:':;' ,'.' :.:'-"
1.0
I 1.0
I 1.0 I
1.3
I
2)
3.2.5.2 For loads and load effects that are well
controlled a reduced load coefficient Yf = 1.2 may be
used for the P and L loads instead of 1.3 in load
~ondition a.
Guidance Note:
A load coefficient of 1.215 for projects within the petroleum actiVities
on the Norwegian continental shelr, subject 10 NPD's approval.
3.2.5.3 Where a permanent load P (e.g. self weight or
hydrostatic pressure) causes favourably load effects a
load coefficient 1f 1.0 sball be used for this load in
=
load condition a.
3.2.5.4 In eases where the load is tbe r"l'ult of
counteracting and independent large bydrostatic
pressures the appropriate load coefficient sball be applied
to the pressure difference. However, the pressure
difference sbould .n ot be taken less tban 0.1 times the
hydrostatic pressure.
3.2.5.5 In dynamic problems special considerations of
application of the load coefficients are necessary. In lieu
ofa refined analysis, e.g. sucb as indicated in 3.1, the
load effects may be found by application of load
coefficients after baving found the responses, e.g. after
baving splved tbe equations of motion for vessel motion
response analysis .
VerilY tbat the damaged structure may resist the
design loading effect caused by P, L, D, and E
without the occurrence of a global mode of
NA
failure, see 3.2.2.2. See also Table 3.2, loading
condition d.
Load categories P, l ; 0, E and A are described In Pl.1 Ch.3 Sec.3.
))
Determination of effects (damages) caused by an
accidental situation on the intact structure. For
Table 3.2 - Load factors for PLS
·;;g~~i~~·h: /.f~: :~~':~';.~/, ;\~~: :~ t~: ·~~;~~~.~~·;~i.~! /'~~>~~~~~_f~
''''·''''''::'.'''','', h 1.0 I 1.0 I 1.0 I NA I 1.0
,;d -;· .',.>. ":'., 1.0 I 1.0
1.0
1.0 I NA
load categories P,l, D. E and A are described in Pt.1 Ch.3 5eO.3.
3.2.7 Fatigue limit state - FLS
3.2.7.1 For marine operations of long durations and
with elements exposed to high cyclic loads tbe
possibilities and effects of fatigue should be considered.
3.2.7.2 The fatigue limit state (FLS) sball be evaluated
according to procedures given in a recognised code or
standard. Such evaluation should be based on the
defined operation period and the anticipated load history
during the marine operation
3.2.7.3 All load coefficients sball be
Y = 1.0
f
3.2.7.4 If a deterministic approacb by calculating a
Miner sum is used, the Miner sum sball not exceed the
values indicated in Table 3.3.
3.2.6 Progressive collapse limit state - PLS
3.2.6.1 Possible accidental situations sball be
considered against whicb sufficient local strengtb cannot
be provided by reasonable means, or against whicb
increased local strengtb would reduce the safety against
overall failure of the structure.
The elements shall be categorised according to
3.2.7.5 Lower values for the Miner sums may be
relevant if tbe structure bas been or will be subjected to
fatigue loading before or after the considered marine
operation. In sucb eases the maximum allowable Miner
sum for the actual marine operations sball be determined
by considering tbe total load history the structure will be
exposed to.
DET NORSKE VERIT AS
RULES FOR
PLANNING AND EXECUTION OF
n
MARINE OPERATIONS
;RImr-!!::!IJWW
PART 2 : OPERATION SPECIFIC REQUIREMENTS
)
·0
PART 2 CHAPTER 1
LOAD TRANSFER OPERATIONS
JANUARY 1996
SECTIONS
1. INTRODUCTION ................................ . ... .. ... .......................... ............. .................................... 5
2. LOAD OUT ................................................ ......................................... .......... ....................... 7
3. FLOAT OUT ............................. .............. ................. .............................. . ............................. 15
4. LIFT OFF ........................................................................................................................... 18
5. MATING ............................................................................................................................ 23
6. CONSIRUCTION AFLOAT .............. .... ............... ... ................................................................ 27
DET NORSKE VERITAS
Verilasveien I, N-1322 H0Vik, Norway Te\.: +4767579900, Fax.: +47675799 11
CHANGES IN THE RULES
This is the first issue of the Rules for Planning and
Execution of Marine Operations, decided by the Board
ofDet Norske Veritas Classification AlS as of December
1995. These Rules supersedes the June 1985, Standard
for Insurance Warranty Surveys in Marine Operations.
These Rules come into force on 1st of January 1996.
This chapter is valid until superseded by a revised
chapter. Supplements to this chapter will not be issued
except for minor amendments and an updnted list of
corrections presented in the introduction booklet.
Users are advised to check the systematic index in tbe
introduction booklet to ensure that that the chapter is
current.
)
)
@ Det Norske Vcritaa
Computer Typescuing by Del Norskc VeriLaIi
Printed in NOrWay by the Oct NOIlike VeritasJanuary 1996
1.96.600
Rules for Marine Operations
"1.. 2 Ch.l Load Transfer Operations
January 1996
Page 3 of 28
j
CONTENTS
.)
2.6
LOAD OUT VESSEL.............................. 12
2.6.1 General ................................. : .. .. .. 12
2.6.2 Structural strength ........................... 12
2.6.3 Documentation ............................... 13
2.6.4 Stability afloat ................................ 13
2.6.S Maintenance .................................. 13
2.7
OPERATIONAL ASPECfS .. .. .................. 13
2.7.1 General ...... ......................... . .... .... 13
2.7.2 Load out site ... .. ............................ 13
2.7.3 Preparations .......·.............. .... ......... 13
2.7.4 Grillage and seafasteruog ................... 14
2.7.5 Monitoring ................................... 14
2.8
SPECIAL CASES ............ ....................... 14
2.8.1 Load in ........................................ 14
2.8.2 Barge to barge load transfer ................ 14
3.
FLOAT OUT ....................................... 15
3.1
INTRODUCTION .................................. IS
3.1.1 Application ................................... 15
3.1.2 Planning and design basis ........ ......... . 15
LOADS ................... ... .. ... ..... ................ 7
2.2.1 General .................... ..................... 7
2.2.2 Weight and CoG .............................. 7
2.2.3 Weight of load out equipment .............. 8
2.2.4 Environmental loads ......................... 8
2.2.5 Skidding loads ................................ 8
2.2.6 Skew load ...................................... 8
2.2.7 Other loads .................................... 8
3.2
LOADS ....................... ...... .. ... ... ......... . IS
3.2.1 Geoeral ....... .. ... ................ .. ... : ...... IS
3.2.2 Weight ......................................... IS
3.2.3 Buoyancy ..................................... 15
3.2.4 Other loads ................................... IS
3.3
LOADCASES AND ANALYSIS OF FORCESI5
3.3.1 Basic loadcases and structural analyses .. IS
2.3
LOAD CASES AND ANALYSIS OF FORCES 9
2.3.1 General .. ...... .. ... . ........... ................ 9
2.3.2 Loadcases ...................................... 9
3.4
STRUCTURES ................. .. ................... IS
3.4.1 General ........................................ 15
3.4.2 Stability afloat. ............................... 16
2.4
STRUCTURES AND SOIL ........................ 9
2.4.1 General ......................................... 9
2.4.2 Quays ........................................... 9
2.4.3 Soil .............................................. 9
3.5
SYSTEMS AND EQUIPMENT.................. 16
3.5.1 General ........................................ 16
3.5.2 tnstallation systems .......................... 16
3.5.3 Air cushion systems ......................... 16
3.5.4 MooringlPositioruogrrowing System .... 16
2.S
SYSTEMS AND EQUIPMENT ................... 9
2.5.1 Geoeral .... ....... .............................. 9
2.5.2 Push/pull systems ..... : ....................... 9
2.5.3 Trailers ................. . .................... .. 10
2.S.4 Skidding equipment ......................... 10
2.5.5 Barge ballast system ......................... II
2.S.6 Power supply ................................. 12
2.S.7 Testing ........................................ 12
2.5.8 Mooring and fendering ..................... 12
3.6
OPERATIONAL ASPECTS ...................... 16
3.6.1 General .......... ........ ...................... 16
3.6.2 Float out site .................... . ........... . 16
3.6.3 Clearances .................................... 16
3.6.4 Monitoring .... ................. . ............. 17
1.
INTRODUCTION .•................•.•..•.. •....... 5
1.1
GENERAL ............................................ 5
1. 1.1 Application ... . .... . ..... .... .... ... .. ........ . 5
1.1. 2 Terminology ................................... 5
1.1.3 Symbols ........................................ S
1.2
DESIGN PHASE .................................... S
1.2.1 Planning and design .......................... 5
1.2.2 Documentation ............ .... ................ 6
1.3
OPERATIONAL ASPECTS ....................... 6
1.3.1 Preparations ................................... 6
1.3.2 Recording and monitoring .................. 6
1.3.3 Weather forecast. ................ .... ..... .... 6
1.3.4 Organisation ... ............ ......... ... ........ 6
}
2.
LOAD OUT .......................................... 7
2.1
GENERAL ............................................ 7
2.1.1 Application .................................... 7
2. 1.2 Plamiing and design .............. ............ 7
2. 1. 3 Load out class ................................. 7
2.2
)
DlIT NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.l Load Transfer Operations
January 1996
Page 4 of2S
)
4.
LIFT OFF .......................................... 18
5.4
4.1
GENERAL .................................. . .......
4.1.1 Application ... . ..............................
4.1.2 Planning and design basis .................
4.1.3 Lift off class ......... .............. ... ... ....
18
18
18
18
STRUCTURES ............................ .. ........ 24
5.4.1 General .......... .. ....... ...... ............ ... 24
5.4.2 Barge supports .................•..... .. ... ... 24
5.4.3 Substructure .............. •................ .. . 24
5.5
4.2
LOADS .... ... .................. ...... . ........... '"
4.2.1 General ............. ..... . ........ ... .........
4.2.2 Skew loads ................. ..... ........ .. ...
4.2.3 Other lo.ds ............................ .. .....
18
18
18
19 '
SYSTEMS AND EQUIPMENT .. .............. .. 24
5.5.1 General .................... ... ..... .... ........ 24
5.5.2 Multi barge ballast systems ............. .. .24
5.5.3 Substructure ballast and sounding systems24
5.5.4 Primary positioning system ................ 25
5.5.5 Secondary positioning system ........ .... .. 25
4.3
LOADCASES AND ANALYSIS OF FORCES19
4.3.1 General .................... ................... 19
4.3.2 Basic loadcases and force distribution .. . 19
5.6
4.4
STRUCTURES ....... ....... ... ......... ...... .....
4.4.1 General .............. . ................ .. ......
4.4.2 Object.. ............ . . .........................
4.4.3 Plnstruction supports ......................
4.4.4 Barge supports ...............................
OPERATIONAL ASPECTS ......... ... .......... 25
5.6.1 General .. ...................................... 25
5.6.2 Mating Site ................... ................ 25
5.6.3 Preparations .................................. 25
5.6.4 Clearances ..................................... 26
5.6.5 Monitoring and monitoring systems ...... 26
6.
CONSTRUCTION AFLOAT .. . ..•..•.•. ... ••. .27
6.1
INTRODUCTION ..... . ............................ 27
6.1.1 Application ................................ ... 27
6.1.2 Planning and design basis ........... . ...... 27
6.2
LOADS ................................... .... ........ 27
6.2.1 General ...... ................. .. .... ....... .... 27
6.3
STABlUTY AFLOAT .... ........ . ................ 27
6.3.1 General ..................... ............. ...... 27
6.3.2lnclining tests . ...•.. .. .... .. ........... ...... .27
6.4
MOORlNG ........................................... 27
6.4.1 General ........................................ 27
6.4.2 Anchor lines ..... .. ............. ..... ......... 28
6.4.3 Auxiliary anchoring equipment.. .......... 28
6.5
OPERATIONAL ASPECTS .. .. ............. ..... 28
6.5.1 General . .................. ........... ..... ..... 28
19
19
19
19
19
4.5
SYSTEMS AND EQUIPMENT ........ .. ....... 20
4.5. 1 General ........... ..... ............... ... ... .. 20
4.5.2 Ballast system .. ............................. ·20
4.5.3 Positioning systems .......... ............... 21
4.6
UFT OFF VESSELS ........... ..... ..............
4.6.1 General ................ ... ..... ...............
4.6.2 Structural strength ...................... ....
4.6.3 Stability afioaL .......... ....................
21
21
21
21
OPERATIONAL ASPECTS ....... .......... . ...
4.7.1 General ..... ... .. .... ........... . .............
4.7.2 Lift off site .............. .. ...................
4.7.3 Preparations ..................................
4.7.4 Clearances ........... ... .................. . .. .
4.7.5 Monitoring and monitoring systems .....
21
21
21
22
22
22
4.7
)
5.
MATING ..... •• .•.•.. •.•................•....•....• 23
5.1
INTRODUCTION ...... . .......... ... ............ . 23
5.1.1 Application ... ............................... 23
5.1.2 Planning and design basis .......... ....... 23
5.2
LOADS ............ .................. ...... ... ... .... 23
5.2.1 General .... ... ...... .. ............ ............ 23
5.2.2 Skew loads . ................................. . 23
5.3
LOADCASES AND ANALYSIS OF FORCES23
5.3.1 Basic loadcases and force distribution ... 23
5.3.2 Additionalloadcases ..... .......... ..... .... 23
5.3.3 Deck horizontal restraint ...... ............ 24
Table List.
Table 2.1 - Load out class definition ........ ....... ........ 7
Table 2.2 - Friction coefficients .......... ..... ........ .... . 8
Table 2.3 - Push/pull requirements .. ..................... 10
Table 2.4 - Ballast capacity requirements ....... .. ...... 11
Table 4.1 - Lift off class definition .................. ..... 18
Table 4.2 - Ballast capacity requirements ........... ... . 20
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.l Load Transfer Operations
January 1996
PageS of28
1. INTRODUCTION
1.1 GENERAL
Mating: The activities necessary to join two floating
objects. The floating objects may be supported by
barges, pontoons, etc.
1.1.1 Application
o
)
1.1.1.1 Pt.2 Ch. !. Load Transfer Operations. gives
specific requirements and recommen~tions for load out,
float out, lift off and mating operations. This chapter
also applies for the construction afloat phases.
1.1.1.2 General requirements for planning, design and
Object: Structure subjected to one or several of the
operations defined in this paragraph.
Site move .: The activities necessary to transfer an object
from one location at the yard to another.
execution of marine operations are given in Pt. 1 Ch.2.
1.1.3 Symbols
1.1.1.3 Re<juirements generally applicable for load
chapter.
transfer operations ,are given in this section. Sections 2
through 6 include requirements for the different types of
operations.
1.1.1.4 For load transfer operations carried out by
crane lifting reference is made to Pt.2 Ch.5.
1.1.~.5
The towing aspects of load transfer operations
are covered in Pr.2 Ch.2 and Ch.3.
1.1.1.6 Conditions for using these Rules are slated in
Pt. 0 Ch.! Sec. 1. 2.
1.1.2 Tenninology
1.1.2.1 Definitions of terms are given in Pt. 0 Ch.I.
Terms considered to be of sp"",ial importance for this
chapter are repeated below.
1.1.3.1 The list below defines the symbols used in this
Centre of gravity.
Expected dynamic skidding load.
Expected slatic skidding load.
Minimum effective freeboard.
GBS: Gravity Base Structure.
Initial melacentric height.
GM:
HIIlllJ[ : Maximum anticipated waveheight.
PLS: Progressive (coUapse) Limit Slate.
Additional loads during skidding.
P dyn :
p. :
Additional break loose loads during skidding.
Operation Reference Period.
T. :
W:
Weight (of object).
Weight of load out equipment.
W", :
Dynamic friction coefficient.
I-ldyn :
Static friction coefficient.
fl.:
CoG:
Fdyn :
F. :
fmio :
1.2 DESIGN PHASE
Float out: The ac.t ivities necessary to transfer an object
from a dry construction site to a ,self floating condition
outside the construction site.
Load in : The activities necessary to tiansfer an object
from 8 vessel to land, i.e. a reversed lo~d out.
Load out : The activities necessary to transfer an object
from land onto a vessel by a horizontal movement of the
object.
Load transfer : The activities necessary to transfer an
object from one support condition to another.
Lift off: The activities necessary to transfer an object
positioned on land or sea bed supports into a floating
1.2.1 Planning and design
1.2.1.1 General requirements to planning and design
are given in Pt.! Cil. 2.
1.2.1.2 The design effects of all extreme environmental
conditions need to be evaluated. The effects should be
considered in the design calculations and if applicable be
taken care of by operational limitations.
1.2.1.3 The operation should be defined as either
weather restricted or unrestricted, see Pt. ! CIr.2 Sec. 3. 1.
condition.
1.2.1.4 Sensitivity studies should be carried out
Lift on : A reversed lift off. I.e. the activities necessary
to transfer an floating object onto land/sea bed supports.
according to Pt.! CII.3 Sec. 3. 2. 2. whenever relevant.
DEf NORSKE VERIT AS
January 1996
Rules for Marine Operations
Pt.2 Ch.l Load Transfer Operations
Page 6 of 28
1.2.2 Documentation
1.3.2 Recording and monitoring
1.2.2.1 General requirements to documentation are
given in Pt. 1 Ch.2. Sec.2.2.
1.3.2.1 During the operation a detailed log should be
prepared and kept, see Pt. 1 Ch.2 Sec. 2.2. 5. The
following sbould be recorded;
.
1.2.2.2 The following design documentation are
environmental conditions,
normally required;
the sequence of events and
all monitoring. results.
.-
documenting of adequate strength and capacity of
all involved equipment and structures,
documentation of civil elements (soil, quay,
bollards, etc.) engineering calculations,
barge data, stability and strength verifications,
and
ballast calculations covering the planned
operation as well as contingency situations.
1.2.2.3 Evaluations and calculations of expected
monitoring results should be presented. Acceptable
tolerances should be stated and documented.
1.2.2.4 An operation manual must be prepared, see
1.3.2.2 Monitoring of environmental conditions shall
be carried out according Pt. 1 Ch.2 Sec.3.2.3.
1.3.3 Weather for!!CllSt
1.3.3.1 The operation manual sbould clearly define
weather limitations and requirements to the weather
forecast, see Pt. 1 Ch.2 Sec. 3.2.
1.3.3.2 Weather effects such as swell and tide could be ()
of significant importance for load transfer operations and
should be duly considered.
Pt.1 Ch.2 Sec.3.5.
1.3.4 Organisation
1.2.2.5 Before the start of the operation;
certificates,
1.3.4.1 General requirements to the organisation and
test, survey and NDE reports, and
classification documents
communication during load transfer operations are given
in Pt. 1 Ch.2 Sec.3.3.
for structures, equipment and vessels involved should be
presented, as applicable.
o
Guidance Note
Load transfer operations will in many cases involve personnel which
are not participating in this type of operation on a frequent basis.
Personnel exercising and briefing are hence of great importance,
see pt.! Ch.2 Seo.3.4..2.
1.3 OPERATIONAL ASPECTS
1.3.1 Preparations
1.3.1.1 The environmental conditions, including the
forecasts, should be such that the operation can be
completed in a well controlled manner and in accordance
with the design assumptions and the operational
limitations for the objects involved.
1.3.1.2 All structures and equipment necessary for the
operation sbould be correctly rigged and ready to be
used.
1.3.1.3 For operations or phases of operations that may
be carried out in darkness sufficient lighting should be
arranged to be present during the entire operation.
1.3.1.4 The involved area should be checked for
obstacles which may unduly delay the operations.
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.l Load Transfer Operations
January 1996
Page 7 of28
2. LOAD OUT
2.1.3 Load out class
2.1 GENERAL
2.1.1 Application
2.1.1.1 This section applies for transfer of heavy
objects from land onto a transport vessel or barge, i.e.
load outs.
2.1.3.1 Requirements to load out equipment are defined
according to load out classes. The load out shall, based
on tide conditions, restrictions w.r.t. weather and repair
possibilities be classified according to Table 2.1.
Table 2 1 - Load out class def1nition
1'1
)
2.1.1.2 As applicable this section applies also for site
moves. Site moves could be defined as load out Class 4
or 5, see 2.1.3.
2.1.1.3 Load in and barge to barge load transfer
operations are generally covered by this section. Special
requirements for such operations are given in 2.8.1 and
2.8.2.
Slgnlficant
Significant
Yes
No
SloniRcant
No
No
No
Zero
Zero
NofYes
Yes
No
1
2
Yes
No
4
6
3
Notes
- A Significant tide range indicates that ballasting Is required to
compensate for the tide variations.
- Ir the baUast system cannot compensate for a complete tide
cycle the load out Is defined as "tide restrfcted~, I:e. Class 1,
see also 2.5.5.5 below.
- Requirements (or weather restricted operations are given in
PI.1 Ch.2 Sec.3.1.
2.1.2 Planning and design
2.1.2.1 General requirements are given in 1. 2.1.
2.1.2.2 Tide variation, which is normally the most
critical parameter for load outs, should be specially
evaluated,
2.1.2.3 The operation reference period, T R , defined in
Pt.1 Ch.2 Sec. 3. 1, should be established at an early
stage. The start and end points for load out operations
should be clearly defined.
2.2 LOADS
2.2.1 General
2.2.1.1 Loads and load effects should be established
according to Pt. 1 Ch. 3 .
Guidance Note
Start points (or load out operations should at the latest be defined
when the load out equipment start to enter out over the quay side.
The object should be in final pOSition and the seafastenlng started In
order to define the load out as completed.
2.1.2.4 Other items of importance for planning of load
out operations are;
yard lay-out, including position of object,
barge dimensions and strength,
object position and support height on barge,
load out route survey w.r.t clearances and
obstructions,
water depths,
quay and ground strength and condition.
2.2.2 Weight and CoG
2.2.2.1 The weight (W) is the characteristic weight of
the object as defined in Pt.1 Ch.3 Sec.3.5.2.
2.2.2.2 Any possible CoG position should be
considered for support geometry's or system layouts
sensitive to CoG shifts. It is generally not recommended
to substitute a CoG envelope study by a weight
inaccuracy factor, see also Pt. 1 Ch.3 Sec. 3.5.3.
2.2.2.3 If there are significant uncertainties w.r.1.
weight and C.o.G position, sensitivity analysis should be
carried oul. The appropriate weights and CoG's to be
used may be evaluated separately for strength and ballast
purposes.
DET NORSKE VERITAS
January 1996
Page 8 of 28
Rules for Marine Operations
Pt.2 Ch.l Load Transfer Operations
2.2.3 Weight of load out equipment
2.2.3.1 The weight of the load out equipment (W,,,) is
the total weight of equipment and support structures
whicb moves witb the transported object. Sucb
equipment may be support beams. grillages. skidding
sboes. trailers. pusblpull jacks. hydraulic power packs.
etc.
)
2.2.5.4 The friction coefficient values used sbould not
be taken less than specified in Table 2.2 unless adequate
in service documentation indicates that other values may
be used.
Table 2 2 - Friction coefficients
".':...: ~
" j :.':- ,.
\ .' $I~lit.
"Si~iii9's~I:k~~
, .: :-:
.-"
,.... ../" .". --'.' " : ." .,
,,
.
-;:
~. ~ >~~~1n~~:
SteeUSteel
0.30
0.20
Tenon/sleel
0.25
0.10
2.2.4 Environrnentalloods
Tenon/stainless steel
0.20
0.07
2.2.4.1 All load effects caused by tide variations sball
be considered.
TeflonNVood
0.25
0 .08
Waxe<l woodISteel
0.20
0.12
Steel rollers/Steel
0.02
0.02
Rubber wneelS/Asphaft
0.03
0.03
2.2.4.2 Load out operations sbould normally not be
carried out in significant waves and swell conditions.
Loads due to waves and swell sbould bowever be
considered for barge mooring after tbe load out
operation. Wave conditions and loads should be
determined in accordance witb Pt. 1 GIJ.3 Sec. .2 and 3.
2.2.4.3 Wind and current loads sbould be determined in
accordance witb Pr.1 GIr.3 Sec.3.4.
';:.::
Note~
-
It Is assumed that the sliding surfaces are properly
lUbricated.
-
Break out factor to account for extra loading due to long term
effects such as adhesion, settlements, etc. is Included in the
static coerticlents.
-
The values are valid only for contact stresses lower or equal
to the allowable cl;lntact stresses for the considered medium.
Allowable contact stresses should be obtained from the
manufacturer or from an applicable code or standard.
2.2.5 Skidding loads
2.2.5.1 The expected static and dynamic skidding loads
are respectively tbe loads required to start and to
continue moving the object. These loads are expressed
as;
F,
= J.1. (W+W.,J +
F dyn
p.
where
F. : Static skidding load.
Fdyn: Dynamic skidding load.
~
Dynamic friction coefficient. see 2.2.5.4.
W : See 2. .2.2.
W .... : See.2.2.3.
p. :
:
Any other load occurring during break out. see
also .2.2.5. .2.
Any otber load occurring during skidding. see
also 2.2.5.2.
2.2.5.2 Effects of inertia. environmental loads and
slope of the skidding or rolling surface should be
considered and if relevant included in tbe skidding loads.
)
2.2.6.2 Skew loads could normally be disregarded for
load out operations where the object bas a 3 point
support system. This could be obtained by including a
reliable load equalising system.
Static friction coefficient, see 2.2.5.4.
:
~yn:
Pdyn
2.2.6.1 Skew load is tbe extra loading at object support
points due to inaccuracies in the level of tbe skidways.
rolling surfaces, supports, etc.
= ~yn (W+W,.) + Pdyn
Eq.2-1
)
2.2.6 Skew load
2.2.5.3 If two or more pusblpull systems are used the
effect of maximum possible differential pusblpuilioads
sball be considered.
2.2.6.3 For cases not covered by 2.2.6.2, the skew
load should be determined by considering the stiffness of
the object. tbe supporting structure. the tolerances of
skidways. rolling surfaces and supports. movement of
barge and link beams and load on the barge.
Guidance Note
In lieu of a more refined analysiS, the skew load may be determined
conSidering the object to be supported by 3 support points only.
2.2.7 Otherloads
2.2.7.1 Any otber significant loads. not covered above
should be considered in tbe design of the object and in
the planning of tbe operation. Such loads may include;
hydrostatic loads on barges.
impact loads.
local support loads all grounded barge bulls.
mooring loads. and
guiding loads.
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.l Load Transfer Operations
January 1996
Page 9 of2S
2.3 LOADCASES AND ANALYSlS OF FORCES
2.3.1 General
2 .3.1.1 Relevant load cases and load combinations
should be established according to the principles outlined
in Pt. 1 Ch.4.
(.0
2.3.1.2 A load out operation does not represent one
well defined loadcase, but a sequence of different
lo.dcases. 10 principle, the entire load out sequence
should be considered step-by,step and the most critical
loadcase for each specific element should he identified.
2.3.2 Lnadca5es
2.3.2.1 Relevant loadcases should be selected in order
to identify design conditions for the object, skidding
2.4.3 Soil
2.4.3.1 Strength and settlement calculations!
evaluations for the ground in the load out area should be
presented.
Guidance Note
The rIsk of differential ground settlements which may influence the
loads during load out, should be minimised by means as;
pre-loadIng of ground In load out tracks and
load spreading by e.g. concrete slabs.
2.4.3.2 Soil material should normally be tested prior to
construction or load out of the object. Alternatively
relevant site investigation reports should be available.
2.4.3.3 For load outs involving grounded barge, the
seabed should be evaluated with respect to topography,
bearing capacity, settlement, etc.
equipment or trailers, support structures and barge.
2.5 SYSTEMS AND EQUIPMENT
2.3.2.2 All loads described in 2.2 shall be considered.
2.5.1 General
2.3.2.3 The force distribution during a load out may
normally be represented .by static loadcases distributing
the object weight and any environmental and equipment
loads to each element.
2.3.2.4 The design loadcases for link beams, Link
beam attachments and the quay should consider mooring
forces and skidding forces when relevant, foreseeing a
situation that the object is jammed for some reason . .
2.3_2.5 For design of the mooring system maximum
loads from pushing or pulling units should be
considered.
2.5.1.1 Systems and equipment to be used during load
out should comply with the requirements given in Pt. 1
Ch.2Sec.5.
2.5.2 Push/pull systems
2.5.2.1 The push/pull systems sball be able to break
loose and push/pull the object to the final position on the
barge.
Guida~ce Note
Adequate break loose capacity may be obtained by combining e.g.
jacks with the continuous push/pull system
2.5.2.2 The push/pull systems for transfer of the object
sball have a nominal capacity equal or greater than the
minimum design capacity defined by the respective load
out class, see Table 2.3.
2.4 STRUCTURES AND SOIL
2.4.1 General
2.4.1.1 Structures and structural elements shall be
verified according to principles and requirements in
Pt.1 Ch.4.
2.5.2.3 The push/pull systems should act in a
synchronised manner in the transfer direction. A
mininaum required load out velocity shall be identified
considering;
maximum allowable load out duration,
length of the load out track,
2.4.2 Quays
maximum anticipated duration of repair work if
2.4.2.1 Strength of load out quays should be
documented. Allowable horizontal and vertical loads
should be defined.
such work is accepted as back up, and
estimated installation time for back up equipment.
2.4.2.2 Calculations showing the actual loads during
load out are less than the allowable loads should be
presented.
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.1 Load Transfer Operations
January 1996
Page 10 of28
2.5.2.4 Back-up push/pull system capacity should be
2.5.3.4 Adequate global structural strength (spine
able to compensate for the following conditions;
strength) should be documented for the actual support
conditions.
a)
b)
Breakdown of one arbitrary self contained
push/pull unit.
Unexpected increase in the skidding loads above
the expected nominal value.
2.5.2.5 Requirements to push/ pull back up systems for
the respective load out class are given in Table 2.3.
Guidance Note
The back-up capacity for accidental conditions repr~sent~ by
2.5.2.4 aJ may be separate push/put! unils with nominal capacity to
complete the operation in the case of a mechanical brea~down of the
main system. The back-up capacity may plso be spare parts of the
main 'Units, if an acceptable repair/replacement time can be proven.
The back-up capacity for conditions represented by 2.5.2.4 b) may
be spare capacity in the main units or back-up push/pull units.
2.5.3.5 Trailers to be used should have adequate
handling capabilities and cargo weight capacity giving
wheel loads within the permissible limits.
2.5.3.6 The support lay-out on each trailer shall ensure
stability in both directions of the trailer.
Guidance Note
A ,trailer with a fullV linked hydraulic suspension need to be regarded
more as a ,distributed load than a support structure. The SUPPorts
on such trailers should be checked for the vertical loading from the
trailers combined with maximum horizontal loads acting on the
trailers, see 2.5.3.7.
\I
2.5.3.7 The trailers should be properly supported to
withstand horizontal loads. These are caused by
2.5.2.6 Any required modifications during the
operation. e.g. removal of pull bars of the push/pull
system lay-out should be proven feasible. Normally.
lay-out modifications should be avoided with the object
supported both at the quay and barge.
"external" effects, i.e. wind, inertia and ground. slope,
in -addition to "internal" effects such as pifferential
traction and steering inaccuracies.
2.5.3.8 The traction system. either the trailers are selfpropelled or pushed/pulled by trucks/winches. should
fulfil the requirements in.2.5.2. Ground surface
conditions should be duly considered.
2.5.3.9 It should be documented that the trailer
hydraulic suspension will work well within the stroke
limits. Support heights. ground slopes/~onditions and
possible barge levels/movements should be considered.
Guidance Note
Normally the planned operational stroke 'should be limited to 70% of
the total theoretically available stroke.
2.5.3.10 Contingency/repair procedures should at least
be presented for;
hydraulic system/hose ruptureslleakage.
tyre puncture,
steering problems and
traction failure. see 2.5.2.
2.5.3 Trailers
2.5.3.1 Trailers (multi wheel bogies) should be used in
accordance with the manufacturer's specifications.
2.5.4 Skidding equipment
2.5.3.2 The hydraulic suspension layout (linking)
2.5.4.1 Skidshoes. steel wheel bogies and steel rollers
should be thoroughly considered. Normally a layout
giving a three point support condition for the object is
recommended.
2.5.3.3 The trailer design load calculations must
consider;
weight of object and relevant equipment.
extreme positions of CoG,
hydraulic suspension lay-out, and
relevant horizontal loads.
are in this subsectIon defined as skidding equipment.
Any part of such equipment used for the horizontal
movement of the object is defined as part of the
push/pull system. see 2.5.2.
2.5.4.2 AdeqUate strength and stability of skidding
equipment should be documented. All possible
combinations of vertical load, horizontal load and
support reaction distribution should be verified.
DET NORSKE VERIT AS
0
Rules for Marine Operations
Pt.2 Ch.l Load Transfer Operations
January 1996
Page 11 of 28
Guidance Note
Guidance Notes
Skidding eqUipment may be connected in order to reduce internal
horizontallcads transfered through the object. The etrect of
possible rotation of skidding equipment should be considered.
The back-up capacity required to compensate for the conditions
represented by a), b) and c) may be spare pumps or spare capacity
in the main pumps.
The back up capacity for accidental conditions represented by d) for
pumps that may not be replaced within the lime available for
replacemen~ may be a spare pump with SUfficient cap~city to
replace the main pump. For pumps that may be replaced ~uring the
2.5.4.3 Skidways level tolerances, surface colldition
and side guides should be adequate for tbe applied
skidding equipment.
load out spare pumps in stand-by position that require a minimum of
lime for replacement may be used.
2.5.4.4 For a hydraulic suspension system, see 2.5.3.2
and 2.5.3.9.
2.5.5.7 Guidance for minimum total ballast capacity
required, including back-up, is given in Table 2.4. See
also notes in the table.
2.5.5 Barge ballast system
o
)
'0
2.5.5.1 Barge ballast systems should have sufficient
capacity to compensate for both change of load and
change of tide during the entire load out operation.
2.5.5.2 Any strength limitations, see 2.6.2.1, andlor
hull deflection restrictions should be considered in the
ballast procedure.
2.5.5.3 It should be thoroughly documented how the
ballasting will be done/controlled for all possible
combinations of tide level and load transferred.
Guidance Note
In order to maintain maximum control with the ballasting it Is
recommended to as far as possible use different systems/tanks for
compensation of;
2.5.5.8 To rely on the barge in~emal pumps as the
primary pumping source during loadou~ should be
carefully considered, bearing in mind the often
unreliable service record of such units and the inherent
inflexibility of the permanent piping systems.
2.5.5.9 Ballasting by air pressurising barge tanks
during the load out operation should be avoided.
Table 2.4 • Ballast caDacitv re uirernents
: "1-#1:.);'
'~.
.
bUr · ':
,Ct~ss· ·
1
• tide.
- weight,
2
- trim, and
- heel.
' NormafOpetaUon c ·
;~i~I~~o,
Yin!i!;l,(:
Iliiltleil"l- . ..: : . ,
Minimum :200% capacity
with intact system and
minimum 120'k capacity
120% capacity
minimum 100% capacity
in all tanks with anyone
DumD sYStem rruled.
Minimum 150% capacity
with intact system Bnd
minimum 120% capacity
In all tanks with anyone
DumD sYStem railed.
Minimum 130'" capacity
with lntact system and a
contingency plan
covering pump system
As for Class 2
2.5.5.5 For load out classes 2 through 5, it should be
documented that the ballast systems have capacity to
compensate for the tide rise/fall through one complete
tide cycle with the load out object in any position.
4
failure.
As for Class 2.
5
As for Class 3
No reaujremenls
No reaulrements
Notes
pump capacity during normal operation is the capacity
- 100'1.
required to carry out the load out at the planned speed. The
required pump capacity for a redpced speed coUld be
acceptable as reference, if ballast calculations are presented
for this case. The maximum allowable operation period
should also be duly considered.
-
100% pump capacity during tide compensation Is the
capacity required to compensate for the niaximum expected
tide variation.
-
A pump system Includes the pump(s) which wilt cease to
operate due to a sIngle failure in any component, see 2.5.5.6
d through g. in the baUast system.
load out due to repair work, etc.
If required, retrieval of the load out object.
Breakdown of ballast pump(s).
Breakdown of power supply, including cables.
Failure of any control panel/switchboard.
Failure of any ballast valve or hose/pipe.
Minim~m
with Intact system and
cumD system railed.
Minimum 130% capacity
with intact system and
minimum 100% capacity
In all tanks with anyone
cumD sYStem railed.
3
c)
d)
e)
f)
g)
.~~~o~tl:. ~.:.:,:~::"!-'. ·;:t~ .:.;:' .~
in all tanks with anyone
2.5.5.4 The nominal ballast capacity should be
determined by the worst combination of expected tide
riselfall and planned load out velocity, see also 2.5.2.3.
2.5.5.6 Back-up ballast capacity is the capacity required
to compensate for the following situations:
a)
Tide levels andlor tide velocities ahovefbelow the
predicted values.
b)
Unplanned stops in object movement during the
, .,'. ' lld.eiZ6i1ijji!.il~liQrt ;; :: ,..':
i:i6]ect'll 'e~i!ll¥ ' ."
'.; <
'
.:
DIIT NORSKE VERITAS
Rules for Marine Operations
January 1996
Page 12 of 28
Pt.2. Ch.l Load Transfer Operations
In
2.5.6 Power supply
2.5.8 Mooring and fendering
2.5.6.1 Adequate power supply and sources for the
ballast pumps and for the push/pull units should be
ensured during the load out.
2.5.8.1 General design requirements to mooring
systems ace given in Pt.} CIr.2 Sec.5.3. Other
additional requirements applicable for load outs are
given below.
2.5.6.2 The need for emergency power supply due to
the following situations should be considered;
a)
Breakdown of one arbitrary power unit.
b)
Breakdown of the common energy supply.
c)
Unexpected increase in the consumption of energy
above the expected value.
Guidance Note
2.5.8.2 For additionalloadcases to be considered see
2.3.2.4 and 2.3.2.5.
2.5.8.3 Facilities for retel)Sioning of mooring lines
should be present and in stand by during the load out,
. Such facilities may be wit\ches, jackS for tensioning, etc.
The back-up capacity for accidental conditions represented by
2.5.6.2 a) and b) may be spare 4nits In stand·by posnlon. The back-
o
up capacity for conditions represented by 2.5.6.2 c). may be spare
capacity in the main unit or a back-up unit installed to assist the
main unit.
·2.5.6.3 Sufficient main and back-up power supply
capacity should be documented by calculations.
2.5.6.4 Guidance for necessary ballast capacity for each
load out class is given in Table 2.4. For evaluations of
back up requirements an independent power supply
)
2.5.8.4 Adequate strength, stiffness and layout of
fenders should be documented.
Guidance Note
Fender design solutions should at least consider,
- possible requirement to a stiff mooring system during load out,
- effect of extreme tide variations,
- possible impact loads, and
- the possibility that the parge could Qhang" on the fenders, see
also 2.7.2.3.
source should be regarded as a "pump system" .
2.6 LOAD OUT VESSEL
2.5.7 Testing
2.6.1 General
2.5.7.1 See general reqUirements in Pt.} Ch.2 Sec.3.4
with respect to testingfcommissioning, test .procedures
and test reporting.
2.6.1.1 General requirements to vessels and barges are
given in Pt.} CIr.2 Sec. 5. 2 and in Pt.2 CI•. 2 Sec.3.2 and
3.3.
2.5.7.2 Commissioning of the ballast pumps should at
least include;
capacity control and
final functional testing not more than two hours
before start of the operation.
2.6.2 Structural strength
2.6.2.1 ·The barge global strength shall be documented
for all possible ballast conditions, see also Pt. 2 Ch.2
Sec. 2. 3.
Guidance Note
Pump capacity control should be carried out with equal or greater
head and similar hose lengths 85 planned used during the operation.
If tan~ ullages are used as capacity measuring means pumped
volumes should be sufficient to obtain minimum 300 mm difrerence
in ul1ages berore and after pumping.
2.5.7.3 For load out operations of class 1 a complete
test run of the ballast system follOWing the procedure for
the load out should normally be carried out.
2.5.7.4 The push/pull units including the spare units
should be tested in both push and pull mode prior to the
2.6.2.2 The strength should be doculIle"ted for all parts
of the barge exposed to local loads. Such parts are
typically;
a)
b)
c)
d)
e)
f)
g)
link bearn/plate support area,
skidwayflaunchnmner, in9luding support area,
deck plate f()r wheel loading,
push/pull system connection points,
hullioeally for horizontal loads from the quay,
bottom structure, if grounded load out and
bollardsfmooring brackets.
load out operation in order to verify the estiniated
friction forces and functioningfcapacities of the
equipment.
)
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.l Load Transfer Operations
January 1996
Page 13 of 28
2.6.5.2 If relevant precautions to avoid freezing in
tanks and ballast systems should be taken.
2.6.3 Documentation
2.6.3.1 Load out vessel documentation such ss;
general arrangement drawing,
hull structural drawings, including any internal
o
)
.(
reinforcement,
limitations for evenly distributed load and point
loads on barge deck
equipment data aDd drawings,
hydrostatic data, curves/tables,
tank plan, including ullage tables,
guidelines for air pressurised barge tanks and
guidelines for grounded barge condition.
should, when applicable, be available or prepared.
2.7 OPERATIONAL ASPECTS
2.7.1 General
2.7. 1.1 Operational requirements are generally
described in Pt. 1 Ch.2 Sec. 3.
2.7.2 Load out site
2.6.4 Stability afloat
2.6.4.1 Sufficient stability afloat should be ensured
during load out. The minimum requirements to intact
stability are given in Pt. 1 Ch.2 SecA.
2.6.4.2 For load out operations the minimum "effective
freeboard" should be;
f .... = O.5m
Guidance Note
Such arrangements may be heating devices (in pump rooms),
additive anU freeze coolant. or any other devices or acHons serving
th~ above purpose.
+ H~.j2
Eq.2-2
where
f.... : Minimum effective freeboard, see the guidance
note below.
~~ : Maximum anticipated waveheight at the site
during load out.
Guidance Note
2.7.2.1 The searoom at the load out site should be
inspected for obstacles. The seabed in front of the load
out quay should be inspected by divers or by an adequate
survey method if the barge underkeel clearance is
considered as critical.
2.7.2.2 Sufficient barge uoderkee.! clearance should be
present for floating barges during and after the load out
operation. Normally tbe clearancesbould not be less
than O.5m.
2.7.2.3 Due attention should be paid to the possibility
for the barge to "bang" on tbe fenders or the quay
structures.
The -effective freeboard- is defined as the minimum verucal distance
from the water surface to any opening, e.g. an open manhole. A
maximum possible tide level 'and any possible barge heelltrim should
be considered. Coamlngs at openings CQuid be installed to increase
the "effective freeboard".
2.7.2.4 A level cootrol of tbe site area should be
performed for load outs with trailers to ensure !,bat the
level tolerances of the trailers will not be exceeded.
Guidance Note
Class approval to use the barge with less freeboard than defined by
the load line certificate is required.
2.7.3 Preparations
2.6.4.3 Normally there is no requirement to document
damsge stability during load out. However, it may be
applicable to investigate the effect on the stability of
incorrect operation of the ballast system.
2.6.5 Maintenance
2.6.5.1 A barge bandling procedure should normally be
presented. The procedure sbould describe berthing, any
relocation. surveys e.g. on-hire and off-hire surveys,
condition surveys etc., moorings (before and after load
out), watchlceeping, need for barge engineer e.g. for
ballasting, etc.
2.7.3.1 See 1.3.1 for general guidelines.
2.7.3.2 Barge supports (if applicable, skidway- and
temporary supports-) levels and horizontal dimensions
should be thoroughly checked to be correct, i.e. within
acceptable tolerances.
2.7.3.3 A set down procedure for the object should be
used in order to ensure that the grillage and seafastening
desigu assumptions are fulfilled.
2.7.3.4 Nominal set down position and set down
tolerances should be marked on the support stools.
2.7.3.5 Suitable shims sbould be present at the support
stools in case of any excessive gaps during set down.
DETNORSKE VERITAS
January 1996
Rules for Marine Operation
Pt.2 Ch.1 Load Transfer Operation
Page 14 of 28
2.7.3.6 It should he ensured tbat skidway surface
condition is as assumed in the friction coefficient
estimate.
2.8.2 Barge to barge load lr3I)Sfer
2.7.3.7 Planned trailer tracks should provide an
adequate surface condition and the tracks should be
marked on the ground and barge.
2.8.2.2 Requirements to load out operations are
generally applicable for barge to barge load transfer
operations as well.
2.7.4 Grillage aJ)d seafastening
2.7.4.1 The main requirements for the grillage and
seafastening structures of the transported object are
presented in Pt.2 CIJ.2 Sec. 2. 3.2.
2.7.4.2 The seafastening should commence immediately
after completion of the load out operation.
)
2.8.2.1 A barge to barge load transfer operation is
defined as the activities necessary to transfer an object
between vessels doing mainly a boriiontal movement of
the object.
2.8.2.3 Barge to barge load transfer operations could b,
complex involving more than two barges, and different
support conditions on one or more of the barg·es. Due
attention should be paid to this fact during planning,
design and execution of tbe operation.
Guidance Note
2.7.4.3 The transported object should be secured to tbe
barge to withstand possible impact loads andlor any beel
and trim prior to moving the barge to another location
at tbe same site for further seafastening.
Guidance Note
As a minimum horizontal acceleraUon of 0.19 should be considered
in any direction. Friction should be neglected in the calCUlations pf
necessary seafastening capacity.
For operation to be carried out Ule level, lrim and h~1
measurements or the barges may not be sUrticient to control the loa(
distnbutlon.
2.8.2.4 Tide effects can he neglected for operations
involving only floating barges if sufficient bottom
clearance is ensured. Hence, tbe operation could be
defined as load out Class 4 or 5.
2.7.5 Monitoring
2.7.5.1 The following load out parameters sbould as
applicable be monitored and recorded, see 1.3.2, prior to
andlor during tbe operation:
I
)
a)
b)
c)
d)
e)
f)
g)
b)
i)
j)
Tide.
Push/pull force.
Straightness and levelness of skidding tracks.
Inclination oflinkbeam.
Level and vertical deflections of tbe object.
Horizontal position of the object.
Barge draught.
Barge beel and trim.
Water level in barge tanks.
Hydraulic pressure and stroke on any
support/equalising jack, e. g. trailer bydraulic
suspension.
2.8 SPECIAL CASES
2.8.1 Load in
2.8.1.1 Requirements to load out operations are
generally applicable for load in operations as well.
2.8.1.2 As load out is the usual operation special
attention sbould be paid to items as optimal tide pbase
for tbe operation and ballast requirements.
DET NORSKE VERITAS
n
Rules for Marine Operations
Pt.2 Ch.l Load Transfer Operations
January 1996
Page 15 of28
3. FLOAT OUT
3.2.3.2 The final buoyancy estimate should take place
3.1 INTRODUCTION
when the final geometry of the object is established.
3.1.1 Application
3.2.4 Other loads
3.1.1.1 This section applies to objects such as gravity
base structures, jacket substructures, loading towers etc.
fabricated in a dry dock, brought afloat and floated out
from tbe fabrication site.
3.1.2 Planning and design basis
3.2.4.1 All loads which may occur due to effects such
as hydrostatic pressure, impacts, guiding, puUing by
tugs and winches, etc. should be considered in the
design of the object and in the plaoning of the operation.
3 ..2.4.2 The value of other loads should be determined
considering operational and equipment limitations. For
determination of accidental loads possible failure modes
should be sought for.
3.1.2.1 General requirements are given in 1.2.1.
3.1.2.2 Any local environmental effects should be
identified and considered.
3.1.2.3 Sensitivity studies, see Pl. 1 Ch.3 Sec. 3.2.2,
3.3 LOADCASES AND ANALYSIS OF FORCES
should include evaluation of;
time limitations due to the tide,
3.3.1 Basic loadcases and structural analyses'
extreme tide variations due to atmospheric and
local environmental effects,
limiting environmental conditions,
3.3.1.1 A float out operation represents different
loadcases from the condition when the self weight is
resting on the fabrication supports to the self floating
c9ndition. 1n principle, the entire float out sequence
should be considered step-by-step and the most critical
loadcase for each specific member should be identified.
accidental conditions, and
structural limitations.
3.2 LOADS
3.3.1.2 The global structural analysis required for .
verification of the integrity of the structure for the float
out operation may be omitted provided that analyses '
3.2.1 General
show that other operations or conditions represent a
more severe condition for the design.
3.2.1.1 Loads and load effects should be established
according to Pl. 1 Ch. 3.
3.3.1.3 The float out operation represents aloadcase
3.2.2 Weight
for the towing/positioning winches, wires, brackets,
quick release hooks, etc. These structures should be
capable of withstanding relevant environmental loads in
addition to the positioning/towing loads.
3.2.2.1 The weight of the object should be calculated
on the basis of accurate specific weights and volumes
andlor weighed or estimated weights of parts of the
object, equipment, etc.
3.3.1.4 Additionalloadcases due to environmental
3.2.2.2 The requirementS of 2. 2. 2 apply.
loads (mooring forces, etc.) should be considered for the
relevant structures (mooring equipment, etc.)
3.2.3 Buoyancy
3.4 STRUCTURES
3.2.3.1 The buoyancy of the self-floating object should
be estimated. on the basis of an accurate geometric
3.4.1 General
model. The buoyancy shOUld be estimated for all
relevant draughts. The position of the centre of
buoyancy should be estimated accordingly.
3.4.1.1 Structures should be designed as indicated in
Pl. l Ch.4.
DET
NORSKE VERITAS
January 1996
Rules for Marine Operations
Pt.2 Ch.l Load Transfer Operations
Page 16 of28
3.4.2 Stability afloat
3.5.4 MooringlPositioningiTowing system
3.4.2.1 The stability requirements in Pt. 1 Ch.2 Sec.4
apply.
3.5.4.1 The mooring/positioning/towing system
(wires, quick release hooks, winches, etc.) should be
capable of controlling the object during the operations.
3.5 SYSTEMS AND EQUIPMENT
3.5.4.2 Design requirements to mooring systems are
given in Pt. 1 Ch.2 S~c.5. 3.
3.5.1 General
3.5.4.3 The wire lengths (elasticity) and tensions
3.5.1.1 Systems and equipment to be used during float
should be selected to avoid horizontal distortion of the
structure during the float out operation.
out should comply with the requirements given in Pt. 1
Ch.2 Sec.5.l.
3.5.2 Insia1lation systems
3.5.2.1 The installation systems or parts thereof (piping
for flooding, grouting, skirt water eva1uation, etc.)
should he inspected for blockage prior to dry-dock
flOOding.
3.6 OPERATIONAL ASPECTS
Guidance Nole
3.6.1 General
The dry~ock , area beneath the skirt compartments shOUld be
cleaned to avoid blockage of piping outletslinlets due to debris, etc.
Fitter !>axes, plugs, etc., should be attached to piping outletsJinlets, if
necessary. to avoid blockage.
3.6.1.1 Operational requirements are generally
described in Pt. 1 Ch.2 Sec.3. See also 1.3.
3.5.3 Air cushion systems
3.6.2 Float out site
3.5.3.1 To achieve sufficient bottom clearance during
3.6.2.1 The dry-dock including the float out channel
outside the dry-dock should be surveyed prior to float
out to verify that the required mininoum underkeel
clearance will he maintained throughout the float out
operation. Obstacles that may damage the object or the
tugs should be removed.
the operations, air cushions may be applied under the
hottom slabs pf the object. An adequate water seal
should be used.
Guidance Note
)
3.5.4.4 The positioning/towing system shouid be
designed to manoeuvre the structure at a safe distance,
see 3.6.3.2, from the dry-dock sides/dock gates.
_
The waler seal should be specified conSidering the underbase
.compartmentaHon, environmental conditions, motions during
operation, horizontal speed and the consequences of Joss of air.
Normally. a water seal of minimum 0.5 m should be used.
3.5.3.2 The system should have adequate redundancy in
all parts such that breakdown of one arbitrary delivery
line, compressor or generator does not sdversely affect
the operation.
3.5.3.3 The air leakage from the air cnshions prior to
lift off shall be less than 5% of the compressor capacity.
After lift off the leakage shall be monitored to assess the
feasibility of continuing the operation.
3.5.3.4 A proper venting system should be designed to
ensure that all trapped air under the base can be let out
when planned.
3.6.3 Clearances
3.6.3.1 AIl sdequate underkeel clearance inside the
dock until a reasonable distance from the dock exit
should be documented.
3.6.3.2 Sufficient side and vertical clearances should be
ensured considering;
the operational arrangement,
environmental conditions,
equipment and vessels to be used,
dock water inlet requirements,
consequences of failure or malfunctioning of any
one of the pulling sources,
guiding and fendering arrangements,
bottom clearance, and
float out velocity.
Guidance Note
The minimum vertical bottom clearance should nat be less than
O.Sm conSidering the maximum draught, motions and applicable trim
and heel.
DET NORSKE VERITAS
Rules for Marine Operations
January 1996
~ ~~~.~2~C~h=.21~Lo~ad~T~ra=ns~f~~O~p=e~ra=ti=·o=ns~________________________________________~~~~e~I~7~o2f~28~
Guidance Note
Nonnally a minimum width of 1.2 times the object breadth Is
recommended for the channel from the dock entrance/gate to open
water. If the object is noated out under winch control along a fender
at one of the channelsfdes, a minimum channel widlh of 1.05 times
the object breadth Is recommended. Channel width less than 1.05
times object breadth should be speclal1y considered. If the channel
width is greater than 4 times the object breadth, it may be regarded
as open water, see Pt.2 Ch.3 SecA.
3.6.4 Monitoring
3.6.4.1 Monitoring and recording, see 1.3.2, of;
·0 -
draught, trim, and underkeel clearance,
position and orientation of the object,
environmental conditions including tide,
air pressure in air pressurised compartments,
air leakage and
water plug
should be carried out prior to andlor during the float out
operation.
1')
DET NORSKE VERITAS
January 1996
P(Il:e 18 of 28
Rules for Marine Operations
Pt.2 Ch.l Load Transfer Operations
4. LIFTOFF
4.1.3 Lift off class
4.1 GENERAL
4.1.1 Application
4.1.1.1 This section applies to objects such as offshore
modules and deck structures lifted off ground supports.
Lift off may be carried out by one or several
barges/vessels.
4.1.1.2 Lift off includes all activities from barge
positioning llP to the object is lifted to an acceptable
-ight above the construction supports. The weight of
",eobject is norma\ly transferred fro", the supports to
the barge(s) by deballasting of thebarge(s) at rising tide.
4.1.1.3 The requirements in this section are also
generally applicable for lift on operations.
Guidance
4.1.3.1 A Lift off Class should as for load out, see
2.1.3, be defined according to Table 4.1.
Table 4.1 - Lift off class definition
)~:g{;>,,5~}~;; i~t~~f~~J'~ tW:JJi~H~: :; ji;~~~;!;:
Significant
Significant
Significant
Zero
Zero
Yes
No
No
No
No
NoNes
Yes
No
Yes
No
1
2
3
4
6
4.2 LOADS
4.2.1 General
Note
As -lift on- Is a rev~rsed ~lift ofF the requirements may for some
items, e.g. positioning, not be rele~nt. Adequate requirements to
these items may be found in section.S.
4.2.1.1 Loads and load effects should be established
according to Pt. 1 Ch. 3.
4.2.1.2 All relevant wave lengths including swell type
wave lengths should be considered.
4.1.2 Planning and design basis
4.1.2.1 General requirements are given in 1.2.1.
4.1.2.2 Tide variation, whic" is normally the most
critical parameter for lift off, should be specially
evaluated.
4.2.1.3 First order wave loads need to be considered
for stiff securing/mooring systems. such as;
mooring arrangements including short lines
without catenary, and
objects partly supported by barges and partly by
landlsea bed supports.
1.2.3 The operation reference period, T R, defined in
I't.1 Ch.2 Sec.3.1 s"ould be established at an early
stage. The start and stop points for the lift off should be
clearly defined.
4.1.2.4 Ally local environment3J. effects, e.g. the
possibility of swell/waves at the lift-off site, should be
identified and considered.
4.2.2 Skew loads
4.2.2.1 Skew loads are here defined as the variation in
support reactions due to fabrication- and operation
inaccuracies. All possible skew loads should he
evaluated and included in the relevant strength
calculations if the effect can not he proven insignificant.
Guidance Note
4.1.2.5 Other items of importance for the lift-off
planning are normally;
operati?nal precautions such as shimming, monitoring, etc., may be
used pnor to and during the operation in order to reduce/ eliminate
potential skew loads.
construction support lay-out, including position
of object,
requirements to Sllpport heights and lay-out of
barge supports and barges.
barges dimensions and strength,
water depths,
quay and ground strength/condition,
accidental conditions and
structural limitations for object, barge supports,
and barges.
DEI' NORSKE VERITAS
I
Rules for Marine Operations
-:- ', Ch.l Load Transfer Operations
January 1996
Page 19 of 28
4.2.2.2 nems which may cause skew load effects are:
00
the barges
Fabrication tolerances for the object and for the
barge supports.
Fabrication tolerances for the barge(s).
Vertical offset of the object for each support
condition.
Barge heel and trim variations.
Movement of barge ceotre of buoyancy, gravity
and flotation relative to draught and ballast
configuration.
4.3,2.4 The force distribution in the object and in the
barges, and their global deflectioos, should preferably be
determined by a 3-dimensional analysis.
loaccurate positioning of barges relative to the
object supports.
Deformation of the object and the barges
including the possible introduction of horizontal
loads.
~
4.3.2.2 Local loads on the object and
during positioning and mooring at the ~onstroction site
after lift off, tow out. etc. should be treated as separate
loadcases.
4.3.2.3 Forces in anchoring. mooring and fendering
equipment/structures due to functiooal and
environmental loads should be considered.
4.4 STRUCTURES
4 .... 3 Other loads
4.4.1 General
4.2.3.1 The corresponding requirements of 3. 2. 4 apply.
4.4.1.1 Structures shall be designed as indicated in
Pt.1 ChAo
4.3 LOADCASES AND ANALYSIS OF FORCES
4.4.2 Object
4.3.1 General
4.4.2.1 Special attention should be paid to the
assessment of local support loads from the barge
4.3.1. 1 The lift off operation, from initial contact
through completed lift off, represents a serie of loadcases
for both the object and the barges. The intermediate
loadcnses due to transfer of ballast in the barges and due
to global deformations of the object and the barges
should be considered.
supports and other external loads.
4.3.1.2 The entire lift off operation should be
c' ·.idered step-by-step and the most criticalloadcase for
t.
specific member of the object should be identified.
4.4.2.2 Vertical deflection tolerances should be
specified reSUlting from the structural analysis of the
object such that unacceptable vertical deflections may be
avoided. The selected deflection tolerances should duly
consider the practical limitations of the shimming
procedure.
4.4.3 Construction supports
4.3.1.3 Accidental load conditions should be ideotified.
see Pt.! Ch.3 Sec.J.B. Identified accidental loads that
cannot be neglected due to low probability, see Pt.!
Ch. 2 Sec.2.3, should be included in the design
calculations.
4.4.3. 1 The construction supports should have
sufficient strength to wiihstand the object self weight and
relevant skew loads, relevant impact loads from vessels,
mooring forces, forces due to environmental loads, etc. ,
occurring during the lift off operation.
4.3.1.4 Local loads acting on the object and on the
barges during the operation sbould be assessed .
4.4.4 Barge supports
4.3.2 Basic loadcases and force distribution
4.3.2.1 The loadcases given in 4.J.! should be
analysed as static loadcases by distributing the self
weight, barge support forces, and other loads to the
actual members of the object.
4.4.4.1 The barge supports should have sufficient
strength to withstand all vertical and horizootal forces
during lift off. The horizontal forces may be reduced by
decreasing the horizontal restraint by means of e.g.
teflon plates.
DET NORSKE VERITAS
January 1996
Rules for Marine Operations
,V~ag~e~2=O~o=f~2=8~____________________________________________~Pt~._2_C~h~.~I~L~o~a~d~T~r~aru==~~e~r~O~p~era~ti=·o~ns~
4.4.4.2 The barge supports should be shimmed in
4.5.2.7 The ballast pumps should be arranged with one
accordance with an appropriate procedure to avoid
control centre on each unit. For multi barge operations
unfavourable distortion and load distributions in the
object or the barge supports, and to accouet for as built
the control centre on one of the barges should also be
defined as the master ballast control centre. The
arrangement should be such that simultaneous
deballasting can be effected for all the relevant tanks at
each stage.
deviations.
4.4.4.3 A flexible support system should be used
between the top of the barge supports and the object in
order to ensure an adequate load distribution to all
supports. The .flexible support system may be obtained
by useing crushing tubes, lead plates, wood, a wedge
system or similar.
4.5.2.8 The back-up ballast requirements shOUld be
determined by considering the following accidental
conditioDS;
a)
TIde levels andlor tide velocitieS abovelbelow the
predicted values.
Breakdown of ballast pumps.
Breakdown of power supply, including cables.
Failure of any control panel/switchboard.
Failure of any ballast valve or hose/pipe.
One compartment darnsge of any barge.
Air leakage and adjustment of air pressure in air
pressurised compartments in submerged barges.
b)
c)
d)
e)
4.5 SYSTEMS AND EQUll'MENT
)
4.5.1 <7eneral
f)
4.5.1.1 The systems used for lift off should be
designed, fabricated, installed, tested according to Pt. 1
Ch.2 Sec.3.4.
4.5.2 Ballast system
g)
4.5.2.9 Guidance for minimum necessary total ballast
capacity, i.e. including back-up, dependent on lift off
class is given in Table 4.2. See also notes below the
table.
4.5.2.1 Barge ballast systems should have sufficient
capacity to compensate for both change of load and
change of tide during the entire lift off operation.
4.5.2.2 Any strength limitations andlor hull deflection
restrictions should be considered in the ballast
procedure.
with intact system and
minimum 100% capacity
In ail tanks with anyone
4.5.2.3 The power supply is regarded as im integrated
')art of the ballast system in this sub-section.
)
.
4.5.2.4 In order to maintain maximum control with the
ballast, it is normally recommended to apply different
ballast tanks/systems for;
3
with intact system and
minimum 120% capacity
In all tanks with anyone
Minimum 130% capacity
with Intact system and a
conUngency plan
covering accidental
tide, and
weight transfer.
Notes
Guidance Note
If system segregation is not prnctical, a combined system could be
applied. In this case it should be thoroughly documented how the
ballasting will be done/controlled for all possIble combinatIons of tide
level and load transferred.
4.5.2.5 The ballast system and procedure should have
operational flexibility to cope with unexpected tide
conditions and accidental situations, see 4.5.2.8.
4.5.2.6 The nominal ballast capacity should be
determined by the worst combination of expected tide
velocity and planned lift off velocity.
100% pump capacity during normal operation Is the capacity
required to carry out the lift off at the planned speed. The
required pump capacity for a reduced speed could be
acceptable as reference, if ballast calculations are presented
for this case. The maximum allowable operation period
should also be duly considered.
100% pump capacity during tide compensation is the
capacity required to compensate for the maximum expected
tide variation.
A pump system Includes the pump(s) which will cease to
operate due to a single failure in any component, see 4.5.2.8
b through e, in the ballast system.
DET NORSKE VERITAS
wes for Marine Operations
January 1996
Page 21 of 28
"2 Co. t Load Transfer Operations
-
I
5.2.10 The back-up systems should be adequately
paroled from the main system sucb tbat failure of any
,mponent does not adversely affect tbe safe conduct of
e operation.
5.2.11 Any umbilicals used for air pressurisation of
,bmerged barge compartments should be connected to
lives at the .barge tanks. Air pressurised barge tanks
.ould be fitled with safety valves.
.5.3 Positioning systems
.5.3.1 General design requirements for mooring and
ositioning systems are given in Pt. 1 Ch.2 Sec.5.3 and
.4. Other additional requirements applicable for lift off
re given below.
)
.5.3.2 See 4.3.2.2 and 4.3.2.3 regarding loadcases to
e considered.
4.6.2.2 The barge deflections sbould be maintained
within an acceptable range during lift off by selecting
adequate ballast configurations for each barge.
Tolerances for the barge deflections sbould be
establisbed considering the maximum allowable skew
loads at tbe barge supports.
4.6.3 Stability afloat
4.6.3.1 Special attention sbould be paid to accurate
interpretation and application of bydroststic data for the
barges. For complicated operations inclining tests may
be relevant to verity the hydrostatic stability parameters .
4.6.3.2 Sufficient stability afloat should be ensured for
single barges during positioning. The following
requirements apply;
a)
b)
c)
GM<! l.Om
Pt. 1 Ch.2 Sec.4.
fmin = O.3m + H_,.I2, see also 2. 6.4.2
.5.3.3 The positioning and mooring system should
rovide for correct alignment and securing of the barges
uring all phases of the operation.
4.6.3.3 The requirements to stability after lift off are
given in Pt. 1 Ch.2 Sec.4.2.
..5.3.4 Facilities to re-tension mooring lines should be
4.6.3.4 For lift off operatio~s carried out with open
manholes tbe minimum "effective freeboard" (f.wJ
during load transfer, including any defined "stop point"
before lift off, should be;
'resent and in stand by position during the lift off. Such
acilities may be winches, jacks for tensioning, etc.
1.5.3.5 Fendering structures should be arranged on the
large sides or the construction pillars to prevent
fmin
= O.5m + H_,/2,
see also 2.6.4.2
lamages to the barges during the lift off operation.
1.5.3.6 The barges should be equipped with guides to
4.7 OPERATIONAL ASPECTS
msure accurate positioning underneath the object prior
a
CO"
'encing the lift off operation.
4.7.1 General
4.7.1.1 Operational requirements are generally
described in Pt.I CiI. 2 Sec. 3. See also 1.3.
1.6 LIFf OFF VESSELS
t6.1 General
4.7.2 Lift off site
4.6.1.1 Requirements to vessels are given in Pt. 1 Ch.2
Sec.5.2 and 2.6.3.1.
4.7.2.1 The lift off site should be surveyed prior to
installation of the barges. The survey should verity that
the barges vertical and lateral clearances are acceptable
for th.e planned operation. Obstacles that may damage
the barges or impede the operation should be removed.
4.6.1.2 For requirements to barge maintenance see
2. 6.5.
4.6.2 Structural strength
4.6.2.1 General requirements to barge structural
strength verification are given in Pt.2 Ch.2 Sec. 2.3.3
alld Sec. 2. 3.4.
4.7.2.2 The site survey should include a seabed survey,
if grounded barges will be used. This survey should
verity that the grounded barges will not be exposed to
local or global support loads exceeding the capacity of
the barge hull.
DIT NORSKE VERITAS
January 1996
Rules for Marine Operations
Pt.2 Ch.1 Load Transfer Operations
fage 22 of 28
J
4.7.3 Preparations
Guidance Note
4.7.3.1 The requirements of 1.3.1 apply.
4.7.3.2 Means for closing leakages in barge tanks
should be available during the operations. Sucb means
may be leak mats, steel plates, welding equipment, etc.
4.7.4 Clearances
Normally a remote reading sounding system should be used for tank
water level control. A back-up system but not necessarily remotely
controlled (e.g. hand ullageing) should be provided. If access to any
tank Is obstructed, e.g. by seafastening supports, alternative access
should be arranged.
Guidance Note
Support reacUon measurements and comparison or the results with
the actual ballast water and tide situation should be performed
continuously during the lift off. The actual devlatlon in total/oad and
moments should be noled for each measurement and' compared
with agreed tolerances.
4.7.4.1 Sufficient vertical clearance sball be maintained
between the underside of the object and the top of the
barge supports during positioning of barges and prior to
tbe weight transfer operation.
Guidance Note
ThIs aearance shOUld relative to a reference tide level, nol be less
-"an 25'" of the tide variation or O.25m. The reference .tide level
I1Duld be defined taking adequately into account the operation
procedure/schedule IncludIng contingencies.
4.7.4.2 During possible mooring at the construction
supports after weigbt transfer from these to the barges
sufficient clearance sball be ensured between the
underside of the object and the top of the construction
supports.
Guidance Note
The minimum vertical clearance at low tide should not be less than
26% of the tide variation or O.25m.
4.7.4.3 Sufficient borizontal clearance between barges
and construction supports sbould be ensured throughout
the operation.
4.7.4.4 A minimum underkeel clearance of O.Sm
should be maintained during.tbe weight trans(er
operation.
4.7.5 Monitoring and monitoring systems
4.7.5.1 The following lift off parameters should as
applicable be monitored and recprded, see 1.3.2, prior to
,
and during the operation:
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
Tide.
Swell,
Support reactions.
Object deflections.
Barge deflections and draught.
Water level in barge tanks.
Air pressure in air pressurised barge
compartments.
Clearance between the barge supports and tbe
object.
Seabed clearances.
Clearance between construction supports and tbe
related object.
DIIT NORSKE VERITAS
o
Rules for Marine Operations
Pt.2 Ch.1 Load Transfer Operations
January 1996
Page 23 of 28
5. MATING
5.1
5 ..3 LOADCASES AND ANAL YSlS OF FORCES
INTRODUCTION
5.1.1 Application
5.3.1 Basic loadcases and force distribution
5.1.1.1 This seclion applies to maling operalion such as
operations typical for joining heavy deck slructures
supported by barge(s) and gravity base structures
togelber. Mating includes ballasting of Ibe structures,
5.3.1.1 The basis loadcases for the deck on barges and
Ibe substructure should be determined by evalualing Ibe
following activities:
positioning, weigbt transfer between structures,
ballasling and deballasting of Ibe slructures to final
draught, see also sec. 6.
5.1.2 Planning and design basis
~ 5.1.2.1
See 1.2. 1 for general requirements.
5.1.2.2 The following paramelers should be considered
in relation 10 operational feasibility and structural
limitations of Ibe deck all barges and Ibe substructure:
Environmental conditions.
Time limitations delermined by Ihe weather
forecasting period.
Geograpbical limitations.
Structural limitations for deck, barges, barge
supports, substructure, etc.
Ballasting of the subslructure to mating draught.
Positioning of the deck on bargeCs) above Ibe
sub.structure.
.
Deballasting of the substructure to contact wilb
Ibe deck.
Deck weight transfer from the barges 10 Ihe
substructure by combined deballasting of the
subslructure and ballasling of the barges.
Removal of the barges and deballasting of the
substructure to inshore hook-up/lowing draught.
5.3.1.2 Each phase of the mating operation should be
considered step-by-slep and Ihe most critical loadcase for
each specific member of the slructures should be
identified.
5.3.1.3 The basic loadcases-for-lhe-substructure are
determined by loads from;
external/internal hydrostatic pressure,
inlemal transfer of ballast water and
deck self weight.
Freeboard and hydrostatic stability.
5.2 LOADS
5.3.1.4 The basic loadcases for Ibe deck on barges are
determined by loads from;
)
5.2.1 General
5.2.1.1 The loads given in 3.2 should be considered for
tbe mating operation.
transfer of deck self weight from the barges to the
subslructure, and
transfer of ballast water in the barges.
5.3.1.5 The loadcases given in 5.3.1.3 and 5.3. 1.4 may
be analysed as static loadcases.
5.2.2 Skew loads
5.2.2.1 Requirements in 4. 2.2.1 apply.
5.3.2 Additionalloadcases
5.2.2.2 An analysis should be performed to verify
whether the skew loading effects remain as permanent
loads after completion of the mating or not.
5.3.2.1 Positioning and mooring loads acling on the
substructure or the deck on barges should be considered.
Adequate protection against positioning loads should be
ensured.
Motion amplitudes due to waves should be determined
according to Pt. 1 Ch.3 Sec.3.3.
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.l Load Transfer Operations
January 1996
Page 24 of 28
5.3.2.2 All realistic accidental load conditions should
be identified. see Pl. 1 CIr.3 Sec.3.B. Identified
accidental loads that cannot be neglected due to low
probability. see Pt.1 CIr.2 Sec.2.2.3. should be included
in the design calculations.
.
5.5.2 Multi barge ballast systems
5.3.3 Deck horizontal restraint
5.5.3 Substructure ballast and sounding systems
5.3.3.1 II) the period from deck weight transfer to the
5.5.3.1 The deballast systems should have sufficient
substrucbJre until the permanent connection between
capacity to complete the deck mating operation within
the til1le limitations determined by the weather
forecasting period.
deck and substructure has been established. the deck
shall be horizontally restrained.
5.5.2.1 The requirements given In 4.5.2 apply. There
is no tide influence, as the substruc~re is floating. hence
Class 4 or 5 is applicablo.
Guidance.Note
5.3.3.2 The capacity of the horizontal restraint
capability shall be sufficient to hold the deCk in a worst
possible damage case including wind heel and possible
effects of current and waves after deballasting to hookup draught. This heel condition may be regarded as a
PLS situation. The effects of friction may be taken into
account.
Normally the operation should be designed to be performed Within a
period of 48 hours.
.
5.5.3.2 Valves used for ballasting/deballasting should
be doubled when installed on self floating structures not
complying with the one compartment damage stability
requirement.
5.5.3.3 One back-up unit should be available for each
ballast pump, compressor, and .g enerator.
5.4 STRUCTURES
5.5.3.4 The ballastldeballast systems should be capable
5.4.1 General
5.4.1.1 Structures shall be designed as indicated in
of levelling the structure by eccentric
ballasting/deballasting to compensate for any shift in the
centre of gravity during the mating operation.
Pt.1 CIr.4.
5.5.3.5 Pipe systems and valves should be designed to
prevent accidental cross flooding and uncontrolled
5.4.2 Barge supports
ingress of water.
5.4.2.1 The barge supports should have IiUfficient
strength to withstand all vertical forces and horizootal
forces introduced by deflections of the deck and the
barges during deck weight transfer.
5.5.3.6 Ballast compartments. which are intended to
remain dry. should have adequate drainage capability to
eliminate free surface effect from uncontrolled ingress of
water. Water detection sensors/equipment sbould be
evaluated.
5.4.3 Substructure
5.4.3.1 The substructure should be protected against
possible accidental loads such as mooring line failure
(not relevant if the mooring lines are slack during deck
mating). flooding of buoyant compartments. dropped
objects. collision loads. etc .• during the mating
operation.
5.5.3.7 Air venting systems from cells and ballast
compartments should have adequate monitoring and
control to prevent excess structural loading during
.
ballasting and deballasting of compartments.
5.5.3.8 Umbilicals for remote power and control
should be adequately protected and be backed up by
additional systems to cover breakdowns or rupture.
5.5.3.9 Power and control systems should have
5.5 SYSTEMS AND EQUIPMENT
adequate redundancy to cover failures to ensure deck
transfer within the defined period.
5.5.1 General
5.5.1.1 The mating systems should be designed.
fabricated. installed. tested and commissioned according
to Pl. 1 CIr.2 Sec. 3.4.
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 th.1 Load Transfer Operations
January 1996
Page 25 of2S
5.5.3.10 Immersion trials should be performed at
selected draughts prior to the mating operation. These
trials should be used to test the performance of the
pumps and power/control systems and water tightness of
the structure.
5.5.4 Primary positioning system
5.5.4.1 General requirements to guiding and
positioning systems are giveo in Pl. 1 Ch.2 Sec.5.4.
5.5.4.2 The substructure and the deck structure should
be secured by primary positioning systems, which
normally are;
a permanent mooring system for the substructure,
see Pl. 1 Ch.2 Sec. 5. 3, and
) the towing fleet for the deck on barge(s), see PI.2
Ch.3 Sec. 3. 2.4.
5.6.1.3 During mating, the relative movements of the
structures due to environmental loads should be carefully
considered.
5.6.1.4 All back-up systems should be ready for
immediate activation during the critical stages of the
mating operation.
5.6.1.5 For mating operations between GBS and deck
structures the schedules for mating ·should be carefully
planned in order to .minimise the time at the minimum
draught. In event of delays the substructure (large
gravity base structure) should be returned to a stand-by
draught, such that the minimum freeboard is not less
than 20 meters. The substructure should have the
capability of remaining at the stand-by draught for an
indefinite period.
5.6.2 Mating Site
5.5.4.3 The primary positioning system should be
capable of securing the structures in the event that the
deck mating operation is interrupted .
5.6.2.1 The following criteria should be considered in
the selection of the mating site:
Environmental conditions
5.5.4.4 The primary positioning system should be
sufficiently accurate to ensure safe navigation and
positioning of the multi barge unit close to the
substructure.
Magnitude and direction of wind, waves, and
current, protection against swell, etc.
Geographical limitations
Feasibility of towing the deck to the mating site,
searoom for mooring, minimum water depth, etc.
5.5.5 Secondary positioning system
5.5.5.1 The secondary positioning system should
ensure accurate and well controlled positioning of the
deck on barges above the substructure. The positioning
should take place without causing local impact loads
exc-e.ding the energy absorption capability of the
pc oning bumpers.
5.5.5.2 The secondary positioning system (winches,
wires, jacks, etc.) sbould have sufficient capacity to
~ resist inertia forces, wind forces, current forces, f)tc.
5.6.2.2 The seabed at the mating site should be
surveyed prior to submergence of the substructure to
mating draught. if the seabed clearance is considered
critical.
5.6.2.3 The location where mating will take place
shOUld be investigated for the possibility of variations in
the density of the water. If rapid changes in density is
possible, density measurements should be performed
prior to and during the mating.
5.6.3 Preparations
5.6.3.1 The requirements of 1.3.1 apply.
5.6 OPERATIONAL ASPECTS
5.6.3.2 All connections between the barges and the
deck structure, which may hamper the lift off, should be
5.6.1 General
properly removed prior to commencement of weight
5.6.1.1 Operational requirements are generally
described in Pt. 1 Ch.2 Sec. 3. See also 1.3.
transfer.
5.6.1.2 The minimum freeboard should not be less than
6 m for large concrete gravity base structures with.open
shafts.
5.6.3;3 A seabed survey at tbe site must be available,
covering the total excursion area. The depth contour
lines shall be drawn in sufficient detail to give an
adequate indication of seabed profile. considering tbe
seabed slopes and actual clearances encountered.
DET NORSKE VERITAS
Rules for Marine Operations
Pl2 Ch.l Load Transfer Operations
January 1996
....i1ge 26 of 28
5.6.4 Clearances
5.6.4.1 For mating operations between GBS and deck
structures, assuming maximum excursions caused by the
environmental loads, the following minimum bottom
clearances apply:
Vertical clearance of 10m.
Horizontal clearance of half the diameter at the
lower end of the substructure.
5.6.4.2 Sufficient clearances between the barge(s) and
substructure should be ensured.
Guidance Note
The nominal sideways clearance during posltioning should be at
leastO.6m.
A vertical clearance or minimum O.25m should be maintained
between the underside of the object and the lop of the subStructure
uring positioning.
If the substructure has underwater horizontal elements limiting the
YJaterdepth a minimum barge uhderkeel clearance of O.tim should
be maintained.
5.6.5 Monitoring and monitoring systems
5.6.5.1 The following parameters should be monitored
manually or by monitoring systems, see 1.3.2, during.
mating operations:
Relative position, orienta~9n, and clearances of
substructure and deck prior to .and during
positioning.
Clearances between barge-deck supports.
Barge trim, heel, and draught.
Environmental conditions (monitoring should
begin well in advance of the operation).
Seabed clearance.
Water level in barge tanks.
Air pressure in air pressurised barge
compartments if applicable.
Open/closed status for barge valves.
The substrucrure's;
waterlevel in cells,
air pressure in cells,
open/closes status for valves,
leakages,
draught, and
heeUtrim.
Submergence rate and motions of the
substructure.
Guidance Note
Normally a remote reading sounding system should be used (or tank
water level control. A back-up system but not necessarily remotely
controlled (e.g. ullaging by hand) should be provided.
Guidance Note
Support reaction measurements and comparison of the results with
the actual barge(s) and substructUre ballast sITuation should be
performed continuously during the mating. The actual deviation In
total load and moments should be noted for each measurement and
compared with agreed tolerances.
DEI' NORSKE VERITAS
January 1996
Page 27 of 28
Rules for Marine Operations
Pt.Z C,h.1 Load Transfer Operations
,
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6. CONSTRUCTION AFLOAT
6.1 INTRODUCTION '
6.1.1 Application
6.2.1 General
6.1.1.1 This section applies for marine aspects related
6.2.1.1 The loads given in 3.2 should be considered
to tbe construction pbase of self floating structures.
during construction afloat.
)
6.2.1,2 Adequate approved precautions (gnides,
6.1.2 Planning and design basis
bumpers, reduction of ballast rate, etc.) should be taken
to avoid damages due to impact loads.
6.1.2.1 General requirements are given in 1.2.1.
6.1, .il. Adequate protection of the structure against
impact loads from dropped objects and vessels used
during the construction should be provided.
6,1.2.3 Sufficient freeboard to any open compartment
6.3 STABILITY AFLOAT
6.3.1 General
should be ensured during all stages of construction
considering the crest height of the design wave for the
operation in question and the consequences for accidental
flooding. For special operations, e.g. mating where the
6.3.1.1 General requirements to stability afloat are
reset:Ve buoyancy is very small, any open compartment
6.3.2 Inclining tests
should preferably be temporarily closed.
6.3.2.1 Inclining tests should be performed at different
6.1.2.4 During heavy ballasting, slip forming and
installation or transfer of heavy loads, special attention
should be paid to hydrostatic stability and adjustment of
moorings, see also 6.3.
6.1.2.5 Adequate watertight integrity should be ensured
at
)
given in Pt. 1 Ch.2 Sec.4.
stages during construction, see Pt. 1 Ch.2 Sec.4.
.
6.1.2.6 Where valves are provided at watertight
boundaries to provide watertight integrity, these valves
should be capable of being operated from the bulkhead
) deck or weather deck, pump room, or other nor;naIly
manned place. Valve positioned indicators should be
stages during construction of floating structures in order
to assess the position of the centre of gravity. This is
partiCUlarly relevant when the calculated value of the
metacentric height is close to the minimum value and if
such a minimum condition is obtained by the transfer of
heavy loads.
6.3.2.2 Inclining tesls for the substructure should be
performed both prior to major tows and prior to mating.
6.3.2.3 Pt.f Ch.2 Sec.4.f.4. describes inclining tests.
provided at the remote control station.
6.4 MOORING
6.1.2.7 All inlets should be adequately protected to
6.4.1 General
prevent damage by entering debris and cables. AIl
internal compartments should be cleared of debris before
6.4.1.1 The requirements in Pl. 1 Ch.2 Sec.5.3 apply.
commencement of an immersion operation.
6.4.1.2 The position of the moored structure should be
6.1.2.8 Systems and equipment to be used in the marine
operations during construction should be specified to
such a detail that complete assessment of the operational
feasibility is rendered possible. An adequate emergency
pumoing system should be provided. The general
rc Irements given in Pl.f Ch.2 Sec.5 should be
complied with.
checked with regard to permanent displacements,
particularly in the first period after installation and after
extreme weather conditions.
6.4.1.3 The penetration depth of direct-embedment
anchors should be verified after the installation.
DET NORSKE VERIT AS
Rules for Marine Operations
Pt.2 Ch.l Load Transfer Operations
January 1996
Page 28 of28
6.4.2 Anchor lines
6.5 OPERATIONAL ASPECTS
6.4.2.1 The anchor lines used for long time mooring
during construction afloat should have a documented
minimum quality, see the guidance note below.
Guidance Note
6.5.1 General
6.5.1.1 Operational requirements are genemlly
described in PI.i Ch.2 Sec.3. See also 1.3.
Chain cables should comply with the reqUirements In DNV
Certification Note 2.6, Certification or Onshore M90Ting Chain.
Steel wire ropes should comply with the requirements In DNV
Certification Note 2.5, Certification or Offshore Mooring Steel Wire
Ropes.
6.4.2.2 The strength of the connecting link for
combined cham and wire systems should not be inferior
to the strength of the anchor line.
6.4.3 Auxiliary anchoring equipment
6.4.3.1 Normally, the total breaking capacity of the
windlass should not be less than the required strength of
the anchor line.
)
6.4.3.2 Cable lifters should have sufficient diameter
and be so designed that unfavourable chain stresses are
avoided. Cable lifters should normally be of cast steel
but ferritic nodular cast iron may also be considered.
6.4.3.3 Chain and wire stopperS should be of a design
which does not bring unfavourable stresses upon the
chain or wire.
6.4.3.4 Possible arrangement for emergency release of
anchor lines should be considered in each case.
6.4.3.5 Fairleads fitted between the stopper and the
anchor should be of the roller type and have swivel
provisions.
6.4.3.6 The fairlead diameter should be sufficiently
large and the design should be such that unfavourable
stresses in the anchor line are avoided.
6.4.3.7 Shackles should be manufactured and tested
according to Veriw Rules for Classification of Mobile
Offshore Units, Part 3, Ch.2, Sec.5.
6.4.3.8 Compensators based on steel springs,
hydraulic/pneumatic spring systems, fibre ropes over
sheaves, etc., may be used.
6.4.3.9 The compensator should be of safe design and
certified materials. Possible standard components used
should be manufactured and tested according to
recognised codes.
DEI NORSKE VERITAS
J
•
n
RULES FOR
PLANNING AND EXECUTION OF
MARINE OPERATIONS
PART 2: OPERATION SPECIFIC REQUIREMENTS
)
)
PART 2 CHAPTER 2
TOWING
JANUARY 1996
SECTIONS
)
1. IN1RODUCTION .... ............... ......... .............. ..... ..... ..............•.•.......................•.••...........•.•..... 4
2. PLANNING AND PREPARATIONS ........ ...... •... ••.. •• ... ......•.........•... ••.........•... •••.• ..... .. .•.•. .•..• , ...... 5
3. TOWING EQUIPMENT ......................... •....••. ...... •.......•.•................... •.... •.•.• •......................•.... 8
4. TOWING OPERATIONS ..........•.......... .. ...... .. .... .. ............................. ..• .. •. ... •...•... ..... .. .........•.... 13
DET NORSKE VERITAS
Veritasveien I, N-1322 Hsvik, NOIWay Tel.: +4767579900, Pax.: +47675799 1\
)
CHANGES IN THE RULES
This is the first issue of the Rules for Planning and
Execution of Marine Operations, decided by the Board
of Det Norske Veritas Classification AlS as of December
1995. These Rules supersedes the Juo~ 1985. Standard
for Insurance Warranty Surveys in Marine Operations.
These Rules come into force on 1st of January 1996.
This chapter is valid uotil superseded by a revised :
chapter. Supplements to this chapter will not be issued
except for minor amendments and an updateP list of .
corrections presented in. the introduction booklet.
Users are advised to check the systematic index in the
introduction booklet to ensure that that the cbapi~r is
current.
)
)
)
0)
@
Oct Noral.:::e VenUla
Computer Typc6etting by Det Norake Ventu
Printed in Norway by the Det Nortke Vcritas January 1996
1.96.600
()
January 1996
Pnge 3 of 14
Rules for Marine Operations
Pt.2 Ch.2 Towing
CONTENTS
I.
INTRODUCTION .••.••...•...•••••.••••.•......••• 4
1.1
GENERAL ............................................ 4
1.1.1 Application .......... ................ .......... 4
1.2
DEFINTIlONS ....................................... 4
1.2.1 Terminology ................................... 4
1:2.2 Symbols ........................................ 4
2.
3.3
TOWING VESSELS ............................... 10
3.3.1 General ............... : ........................ 10
3.3.2 Criteria for selection of towing vessels .. 10
3.3.3 Towing lines ................................. 11
3.3.4 Towing winches ............................. 11
3.3.5 Equipment for personnel transfer ......... 11
3.3.6 Vessel documentation ....................... 11
3.3.7 Inspections and testing ...................... 11
PLANNlNG AND PREPARATIONS .......... 5
4.
TOWlNG OPERATIONS ....................... 13
2.1
PLANNlNG .......................................... 5
2.1.1 General ......................................... 5
2.1.2 Weather routed towing ....................... 5
2.1.3 Unrestricted towing .......................... 5
2.1.4 Documentation ................................ 5
4.1
TOW OUT ........................................... 13
4.1.1 Tow out criteria .............................. 13
4.1.2 Weather forecast.. ........................... 13
4.1.3 Internal seafastening ........................ 13
4.1.4 Towing manual .............................. 13
2.2
DESIGN ....................................... .. ...... 5
2.2.1 Environmental conditions ................... 5
2.2.2 Motions ........................................ 5
2.2.3 Simplified motion criteria ................... 5
2.2.4 Stabilit;y afloat ............................. . ... 6
2.2.5 Loads and load effects ....................... 6
2.2.6 Load cases ..................................... 6
4.2
TOWING .................................... .. ...... 13
4.2.1 Routing .................................... . ... 13
4.2.2 Towing clearances ........................... 13
4.2.3 Towing procedures .......................... 14
2.3
STRUCTURAL DESIGN CALCULATIONS .. 6
2.3.1 General ......................................... 6
2.3.2 Grillage and seafastening .................... 6
2.3.3 Barge global strength ........................ 7
2.3.4 Barge local strength ........................... 7
3.
TOWlNG EQUIPMENT .......................... 8
3.1
TOWING ARRANGEMENT ...................... 8
3.1.1 General ......................................... 8
3.1.2 Main towing line ............................. 8
3.1.3 Towing bridle ............... .. ................ 8
3.1.4 Towline attachments ......................... 9
3.2
BARGES ........................................... ... 9
3.2.1 General ....... ................................... 9
3.2.2 Emergency towing arrangement ............ 9
3.2.3 Anchoring and mooring equipment ........ 9
3.2.4 Ballast and drainage systems ................ 9
3.2.5 Access .......................................... 9
3.2.6 Inspection and testing ........................ 9
3.2.7 Barge documentation ........................ 10
)
DEf NORSKE VERITAS
January 1996
Rules for Marine Operations
Pt.2 Ch.2 Towing
Page 4 of14
1. INTRODUCTION
1.1 GENERAL
1.2.2 Symbols
1.1.1 Application
The list below define symbols used in this cbapter;
1.1.1.1 Pt.2 Ch.2, Towing, give specific requirements
and recommendations for single vessel and barge towing
)
Aexp :
Rx :
operations.
ily :
Guidance Note
RequIrements and recommendations for transportation onboard
ship, towing of multi hull vessels, self floating and self propelled
carrier transports are given in Pt.2 Ch.3. Requirements and
recommendations for transit and positionIng of Moblle Offshore
Unites are given In Pt.2 Ch.7.
B:
~
1.1.1.2 General requirements and guidelines in Pl. 1 of
these Rules applies for towing operations. This chapter
is complementary to Pt.!.
1.1.1.3 Conditions for using these Rules are stated in
PI.D Ch.1 Sec. 1. 2.
1.2 DEFINITIONS
:
BP :
Fdrlft:
g:
Exposed cross sectional area in m"l.
Accelerations in vessel longitudinal direction.
Accelerations in vessel transverse direction.
Accelerations in vessel vertical direction.
Breadth.
Static tug ballard pull in tonnes.
Wave drift forces.
Accelemtion of gravity.
Significant wave height.
Length.
r........,: Length of towline.
MBL : Certified minimum breaking load.
MBr........, : Towline MBL
SWL :
Certified safe working load.
T:
draft.
Vc :
Current velocity.
}f, :
L:
Vw :
Mean wind velocity.
v:
Towing speed.
Interaction efficiency factor.
Shape factor.
0.1« :
'1 :
1.2.1 Tenninology
1.2.1.1 Definitions of terms are included in PI.D Ch.1.
Terms considered to be of special importance for this
chapter are repeated below.
)
Boll<lrd pull - Continuous static towing force applied by
tug. i.e. continuos tow line force
0)
Coastal towing: Towing in waters less than 12 nautical
miles of the coast line.
Object: The object handled during the marine operation,
typically a module, deck structure, jacket, sub-sea
structure, pipes, other equipment.
Grillage: Structural load distributing elements installed
to avoid excessive local loads.
Sea/astening : Structural elements providing horizontal
and uplift support of object during towing operations.
Certified item: Item with a capacity or property certified
by a recognised body.
Inshore towing: Towing in sheltered waters.
Internal seafastening : Securing of loose items within the
handled object.
Offshore towing: Towing in waters more than 12
nautical miles of the coast line.
DET NORSKE VERITAS
0.,
January 1996
Rules for Marine Operations
Pl.2 Ch.2 Towing
PageS ofl4
2. PLANNING AND PREPARATIONS
2.1.4 Docwnentation
2.1 PLANNING
2.1.1 General
2.1.1.1 Towing operations shall be planned and
prepared according to philosophies and requirements in
PI.] Ch.2.
2.1.1.2 Towing operations may be categorised as;
)
weather routed, or
unrestricted.
Guidance Note
For transportation operation the tennination point may be assumed,
unless otherwise agreed, when mooring In receiving port is
completed.
2.1.4.1 The planned towing operation shall be
described by procedures and drawings. Documentation
quality sball comply with requirements in Pt. 1 G1l. 2
·Sec.2.2.
A manual covering the relevant aspects of the towing
operation sball be prepared, see also 4.1.4 and Pt. 1
Ch.2 Sec.3.5.
.
2.1.4.2 Certificates, test reports, and classification
documents for equipment and vessels involved shall, as
applicable, be presented before start of towing
operations.
2.1.2 Weather routed towing
2.2 DESIGN
2.1.2.1 Weather routed towing operations may be
designed for specified environmental criteria, see Pt. 1
Ch.2 Sec. 3. 1
2.2.1 Environmental conditions
2.2.1.1 Characteristic environmental conditions for
2.1.2.2 Weather routed tows shall seck sbelter if
weather situations exceeding the operation criteria are
forecasted or experienced.
2.1.2.3 Ports andlor area of shelter sball be defined in
towing procedures. Entrance, geography and size of
shelter shall be considered.
Guidance Note
For weather restricted towing operations crossing open waters, with
an estimated operation reference period (TR) exceeding 72 houl'S,
and were a Marine Operation Declaration is requested, a ONV
representative Wil normany be required onboard the tug during
towIng, see elsa Pf.t Ch.2 Sec.2.4.1 andSec.3.1.2.
towing operations shall comply with Pt.! Ch.3 Sec.2.
2.2.2 Motions
2.2.2.1 Determination of motions shall comply with
Pt.1 Ch.3 Sec.3.
2.2.2.2 For single barge. towing simplified criteria
according to 2.2.3 may be used for preliminruy design
evaluations.
2.2.2,3 These criteria should be confirmed by more
accurate methods.
2.1.3 Unrestricted towing
2.1.3.1 Unrestricted towing operations are designed for
unrestricted environmental conditions. see Pt.! Ch.2
Sec. 3.1. Note also requirements for tow out given in
4.1.1.
2.2.3 Simplified motion criteria
2.2.3.1 The simplified criteria given below may be
used for preliminruy design evaluations of objects,
seafastening and grillage.
The conditions for using the simplified criteria are;
towing in open sea on a flat top barge with length
.greater than 80m,
barge natural period in roU equal to or less than 7
sec.,
object positioned close to midship and with no
part overhanging the barge sides, and
object weight less than 500 toones
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.2 Towing
January 1996
Page 6 of 14
The simplified criteria (mcluding the component for self
weight) may be taken as;
ay (transverse acceleration due to roll and sway):
0.65 g at waterline , increasing 0.015 g each meter
above the bottom of the object,
ax (longitudinal acceleration due to pitch and
surge): 0.45 g at waterline, increasing 0 .01 g
each meter above the boltom of the object,
az (vertical acceleration due to gravity and
heave), maximum 1.35 g, minimum 0.55 g (both
conditions to be checked) and
wind pressure: lOOON/m2 .
2.2.4 Stability afloat
2.2.4.1 General requirements to stability are given in
Pt.1 C/L2 Sec.4.
2.2.5 Loads and load effects
2.2.5.1 Characteristic loads aod load effects should be
taken according to Pt. 1 Ch.3 Sec. 3.
)
2.3 STRUCTURAL DESIGN CALCULATIONS
2.3.1 General
2.3.1.1 StructuraI strength verifications shall comply
with Pt.! Ch.4.
2.3. 1.2 All load carrying elements without a certified
capacity shall be verified by calculations. Typical
elements requiring separate verification are;
local barg~ capacity,
grillage elements,
seafastening clements and
internal seafastening for items exceeding 5
toones.
2.3.1.3 Global and local conditions with respect to
corrosion shall considered in the design calculations, see
also Pt. 1 Ch.4 Sec. 2. 1.4.
2.3.1.4 Element properties (e.g. strength, capacities,
dimensions, weight etc.) may be verified by having
certified properties. The conditions for the certification
sball be stated, see also Pt. 1 ClJ.2 Sec. 2.2.
2.2.5.2 Additional loads due to barge deflections
should be considered. This is pqrticularly important for
CArgo SllPported by more than two vertical supports over
the length of the barge aod for cargo secured
horizontally with a indetcrmined seafastening system,
see also Pr.1 CIJ.3 Sec.3. 7.
Elements that may be subject for this verification
procedure are;
2.2.6 Load cases
2.3.1.5 Modifications to, or use of certified equipment
outside specified limitations require an acceptance from
the certifying body. Typical examples are;
2.2.6.1 Lond cases for tbe towing operations sball be
according to Pt. 1 Ch.4 Sec. 2. 6.
2.2.6.2 The towing operation should be represented by
a sequence of load cases determined by environmental
loads, wave headings, self weight, relevant accidental
loads, and combinations of these.
barge global strength,
towing brackets,
tawing equipment,
mooring equ'ipment, and
winches and foundations.
exceedance of allowable global bending moments
in restricted waters, and
ballasting below load line.
2.3.2 Grillage and scafastening
2.2.6.3 The most critical load cases for the each
specific member of the object shall be identified.
2.3.2.1 The transported object are nonnaIly supported
nod secured to the barge by seafastening and griUage
elements.
2.2.6.4 Critical load cases may be analysed as qunsistatic load cases, adding loads due to dynamic motions
of the barge with cargo to the static loads caused by the
self weight of the object.
2.3.2.2 The grillage elements shall be used to di stribute
a concentrated deck load to a sufficient number of barge
load carrying elements.
2.3.2.3 Senfastening, including shimming plates, sball
be used to secure the transported object from translntions
in all directions.
}
DEI" NORSKE VERn"AS
Q)
0»)
Rules for Marine Operations
JanWll")' 1996
Pt.2 Ch.2 Towing
Page 7 of 14
2.3.2.4 Grillage and seafastening strength shall be
2.3.4.2 If allowable .deck load is based on "load
verified according to Pt. 1 Ch.4 for characteristic loads
according to Pt.! Ch. 3.
charts", these sball clearly state limitations and/or
conditions with respect to Dumber of loads. spacing
between loads and number of simultaneous acting loads.
It shall also be clarified if stated capacities include or
exclude dynamic loads and i(any design/load factors are
included or not. Applied load and material factors shall
be specified.
Guidance Note
Further guidance ror design of seafastening and grillage systems
are given in VMO 1.2 • Guideline for Grillage and Seafastening
systems.
2.3.2.5 Seafastening for all items exceeding 5 toones
shall normally be verified with calculations.
2.3.2.6 Seafastening design for offshore or inshore
installation operations should allow for easy release and
provide adequate support and horizontal restraints until
the object can be lifted clear of the barge, or launched as
applicable.
Guidance Note
Approved "load chart" shall be used with care, specially for heavy
object (> 500 tonnes). For highly loaded barges separate
analysis/calculations are recommended for verification of local deck
strength.
2.3.2.7 Elements providing horizontal and/or vertical
support after cutting/removal of seafasteniug shaH be
verified for characteristic environmental conditions
applicable for the installation operation.
2.3.2.8 For s..fastening and grillage for harbour moves
see Pt.2 C/,. ] Sec. 2. 7.4.
2.3.3 Barge global strength
2.3.3.1 The global barge capacity shall be confirmed.
For barges or vessels classed with a recognised
classification society it is reCommended to base the
global strength verification on stated allowable shea..: and
bending capacities.
2.3.3.2 For barges without class the global strength
sball be verified according to PI. 1 Ch.4, and with loadS
)
aecording to Pt. 1 Ch.3. The verification shall
considered all relevant loads and load combinations, i.e.
bydrostatic loads, hydrodynamic loads, motion and
weights shall be evaluated
2.3.4 Barge local strength
2.3.4.1 The barge local strength shall be verified.
Local strength verifications shall considered actual barge
condition, i.e. effects of corrosion, local damages,
modifications and structural details shall be taken into
account.
)
VET NORSKE VERITAS
n
Rules for Marine Operations
Pt.2 Ch.2 Towiog
January 1996
Page 8 of 14
3. TOWING EQUIPMENT
3.1.2.3 The main towing line should for offshore
3.1 TOWING ARRANGEMENT
towing have a length Dol less than;
3.1.1
",",eraI
l.,...w,. = 2000 BPIMBl.,...w,.
3.1.1.1 Towing equipment shall be arranged so that
proper control over towed object is ensured.
3.1.1.2 The following items should be considered w.r.t
to structural strength and operational practicalities,
,
Eq.3-2
where
l.,...w,.: minimum tow line length (m)
BP :
static bollard pull of the vessel in tonnes.
MIlL....... : towline MBL in tonnes
towing brnckets on towed objcct,
fuirleads on towed object.
3.1.3 Towiog bridle
arrangement of towing line,
possible fibre rope lowing pennant,
wire lope towing pennant,
chain bridle/wire rope bridle/single leg chain,
flounder plate,
shackles,
rings,
3.1.3.2 Each single leg, components and connections
(shackles. rings etc.) in the bridle shaIl have a MBL not
less than ·the MBL of the main tow line. Reductions of
equipment MBL due to bending in way of fairleads, end
thimbles, and
recovering arrangement.
connections elc. shall be considered. Fairlea.ds shall
have a shape preventing excessive bending stress in the
3.1.2 Main towiog line
3.1.2.1 The minimum breaking load. in tonnes. of the
towing line should he Illken according to Eq. 3-1.
where
BP :
3.1.3.1 A bridle should be used for connection of the
tow line to the towed object. Chains should he used in
the way of chafing areas such as fairlends.
4BP
BP < 25
0.8BP +16.JB~
2.2 BP
25 < BP < 130
BP> 130
Eq.3-1
chain links/wire.
Guidance Nole
Shackles, rings -etc. are normally acceptable if stated safe workfng
load (SWl) Is minimum ·113 of the main towline MBL.
3 .1.3.3 A towing bridle should nonnal\y be attached to
towing brackets.
3.1.3.4 End connections of wire ropes should
static hollard pull of the vessel in tonnes.
Guidance Note
The lower limit of 2.2 BP corresponds to a load factor of 1.3, a
material factor of 1.5 and a OAF of 1.1, .
preferably be spelter ,sockets. Pressed connections fitted
with thimbles may be used. Spliced connections should
be avoided.
length of towing line to be used,
3.1 .3.5 Pennants with lower minimum breaking loads
than the main towline may be attached if a reduction of
the dimensions of the towline attachments is desired.
However the minimum requirements in 3.1.2 shall
tow route,
nlways be complied with.
3.1.2.2 The required towline MBL mayaIso be
influenced by
number of tugs and tow fleet arrangement,
nature of the towed object,
3.1.3.6 A recovery wire rope should be fitled to the
winch design, and
available hack-up/contingency.
flounder plate, or if single leg connections are used, to
the end of the legs. The recovery wire rope should be
lead to a winch in an accessible position.
The recovery wire rope should have a minimum breaking
load not less than 3 times the weight of the bridle or leg.
)
DET NORSKE VERITAS
Q);
Rules for Marine Operations
Pt.2 Ch.2 Towing
January 1996
Page 9 of14
3.1.3.7 Fibre rope pennants should nonnally not be
used where there is adequate depth and sea room to
allow for sufficient shock absorbing in the tow line
catinary.
If fibre rope pennants are used the pennants shall be in ...
new condition. Minimum breaking load of any fibre
rope pellDants shall not be less than;
2.3 times the tow line MBL for tugs with bollard
pull less than 50 tonnes,
1.5 times the tow line MBL for tugs with bollard
pull greater than 100 tonnes, and
linearly interpolated between 1.5 and 2.3 times
the tow line MBL for tugs with ballard pull
between 50 and 100 tonnes
3.2.2.2 The trailing .Iine shall be of floating material
and shall have a minimum breaking load not less than 30
tonnes. The distance from the aft extremity of the lowed
object to the buoy shall not be less than 50 metres. In
add ilion 10 the trailing line, n messenger line of length
100 metres may be considered necessary between the
buoy and the trailing line.
3.2.3 Anchoring and mooring equipment
3.2.3.1 A barge should nonnally have at least one
anchor available for emergency anchoring. A windlass
or similar arrangement should be and capable of paying
out and holding the anchor. The anchor should be
secured with a easy releaSe arrangemeDt.
The anchor line length and MBL shall comply with the
Rules of the Classification Society.
3.1.4 Towline attachments
3.1.4.1 Towline attachments shall be designed to resist
towline pull from any likely direction, with the use of
fairleads if necessary.
3.1.4.2 The ultimate capacity of any towline atlacbment
(bracket, ballard and their foundations) sball not be less
than 1.3 times the minimum breaking load of the
towlipc.
Guidance Note
For barges classed by Del Norske Veritas reference Is made to
Rules for Classification of Ships, Pt.3 Ch.3 Sec,3.
3.2.3.2 Mooring ropes of adequate strength and length
shaJl be available on board.
Guidance Note
It Is recommended to have at least 4 mooring ropes of 110m each
(or 2 of 220m each) available onboard.
3.2.4 Ballast and drainage systems
3.2 BARGES
3.2.1
3.2.4.1 The drainage system and bilge pumps should
comply with the Rules of the Classification Society.
~eroI
3.2.1.1 General requirements to barges are given in
Pt.] Ch.2 Sec.5.2. Strength verification of barge
structure and barge equipmen~shall be according to 2.3.
3.2.4.2 If the barge bilge pumps are out of order or if
bilge pumps are not filled, hilge suction may be arranged
by portable pumps placed on board the barge.
3.2.5 Access
3.2.1.2 Towing equipment shall comply with
requirements in 3.1.
3.2.5.1 The barge shall be equipped with adequate
access means,' allowing safe cntenng from both sides of
the barge during towing.
3.2.2 Emergency lowing arrangement
3.2.2.1 An emergency towing wire rope of with
minimum length equal to barge length shall be connected
to a bridle or single leg connection, and lashed to the
barge side for easy release. A recovery trailing li,oe with
a pick-Up buoy shall be filled to the emergency towing
wire rope.
3.2.6 Inspection and testing
3.2.6.1 The barge, object, equipment, and
arrangements shall be available for inspection before
departure of the tow.
3.2.6.2 Functional testing of machinery that may be
used during the voyage should be performed. The
machinery should be tested in presenr.., or by the
personnel who will operate the systems.
)
DET NORSKE VERITAS
I
I,
Rules for Marine Operations
January 1996
Page 10 of 14
I
Pt.2 Ch.2 Towing
3.2.7 Barge docwnentation
3.3.2.4 Towing force for open sen towing shall be
3.2.7.1 GenernI description of barge systems sball be
sufficient to maintain zero speed under the following
conditions.
presented. Ballast and towing equipment/systems shall
be described in detail.
3.2.7.2 The following main particulars should as a
minimum be described;
object particulars.
name, signal letters, owners and port of registry
of barge.
draught during towing.
stability properties for intact and damaged
conditions,
specification of anchoring and mooring
equipment, and
the class of the barge (if any). length. breadth.
depth. and year of bUild. etc.
)
3.2.7.3 The following main dmwings should normally
be presented;
general arrangement,
load charts if applied.
midship sectioD. longitudinal section and other
plans for evaluation of structural strength. if such
evaluation is found necessruy,
drawings showing arrailgement and scantlings of
towing brackets. boUards and fairleads.
the main and emergency towing arrangement, and
recovering arrangement.
sustained wind velocity
head current velocity
significant wave height
Vw = 20 [mls].
V,
1 [mls]. and
Ii, = 5 [m].
=
3.3.2.5 Towing force for coastal towing and towing in
narrow or shallow waters representing a danger for
grounding, shall be sufficient to maintain a speed over
ground, in safe direction, of minimum 2 knots under
defined environmental design conditions.
Guidance Note
Above requirements are based on the necessity to control the tow
offshore, and to ensure adequate manoeuvrability inshore and In
narrow walers.
Guidance Note
SImplified wave drift force components for single "box" shaped
barges may be calculated according Eq. 3-3, provided;
UB>3.0
BfT> 6.0
v=o
Eq.3-3
where
Fdr1ft
Ha
Wave drift forces
Significant wave heIght
B
Breadth
L
length
T
Dran
v
ToWing speed (through water)
(kNl
1m]
1m]
Iml
(ml
Iknots]
3.3.2.6 Required tug boUard pull shall be estimated
)
3.3 TOWJNG VESSELS
based on calculated required lowing force. tug
3.3.1 General
Unless more accurate calculations of tug efficiency are
made. the CO!1tinuous boU';d pall stated in the bollard
pull certificate shall be multiplied with an efficiency
resistance, and tug efficiency in waves.
3.3.1.1 General requirements to towing vessels are
given in Pt. 1 Ch.2 Sec.5.2.
factors of;
0.85
0.75
3.3.1.2 Towing equipment shall comply with 3.1.
inshore
offshore
3.3.2.7 For towing with short l(lwlines the interaction
3.3.2 Criteria for.selection of towing vessel.s
3.3.2.1 Towing vessels shall be selected to enable;
effective utilisation of ballard pull,
good manoeuvrability.
simple disconnecting opemtions, and
simple recovery.
effects due to propeller mce between tug and the towed
object sball be considered in estimates of required pull.
Unless more accurate analysis are performed an
efficiency factor may be taken as;
I.,..."", > 30m
Eq. 34
3.3.2.2 The towing vessels shall be equipped with a
towing winch. see 3.3.4. Towing with hooks should
only be used for assistance and in sheltered waters.
3.3.2.3 Necessary towing force should be estimated
based on the planned towing route.
where
au..:
Interaction efficiency factor.
Projected cross sectional area of towed object io
m2 .
r,.......:Towline length in metres.
'1 = 2.1 for typical barge shapes.
A.z,.:
DET NORSKE VERITAS
D>
.-
January 1996
Rules for Marine Operations
Pt.2 Ch.2 Towing
Page 11 ofl4
3.3.3 Towing lines
3.3.6 Vessel documentation
3.3.3.1 The requiremenls of 3.1.2 apply. Minimum
required low line MBL shall consider bending of tow
line over stem, or around other tow line guiding/steering
equipment.
3.3.6.1 The following main particulars should normally
be described;
3.3.3.2 Tugs should be equipped with suitable antichnrmg equipment.
3.3.3.3 Gog rope or alternative arrangement should be
provided to prevent athwartship pull from tbe towing
line.
3.3.3.4 For offshore towing one spare towline,
satisfying requirements in 3.1.2, shall be available
onboard, preferably on a second winch drum.
Additionally the following spare equipment should be
kept available on board the towing vessel andlor the
towed object.
1 pennant
2 fibre rope springs, if used
A suitable Dumber of shacldcs, rings, and other
connecting equipment for at least one complete
towing line cpofiguration
3.3.4 Towing winches
3.3.4.1 The towing winch shall be approved according
classification requirements.
3.3.4.2 Winches for open sea towing should be remote
operated from the wheel house and so designed and
instrumented tbat it will be possible to determine the
loads in the wire rope from the drum. As examples, this
may be arranged either directly by use of a load cell or
indirectly when the brake is actuated by hydraulic
pressure.
3.3.5 Equipment for personnel transrer
3.3.5.1 At least one suitable workboat with propulsion
should be carried onboard for transferriug personnel and
equipment from the towing vessel to the towed barge.
If the workboat is of the inflatable type, a flooring of
adequate strength should be fitted to allow the carriage
of heavy objects.
name, signal letters, owners and port of registry I
main engine(s): manufacturer and number,
maximum continuous output and corresponding
r.p.m.,
static continuous bollard pull,
propeller(s): number, type, .whether nozzle is
fitled or nat,
side thrusters (if fitted): position and thrust,
fuel capacity,
fuel cansumption. tonnes per day, and
stability particulars for departure and arrival
loading conditions.
3.3.6.2 Towing vessels sball have a ballard pull
certificates not older than 10 years. The bollard pull test
procedure shall be stated.
If the vessel has undergone significant stru.ctural or
machinery changes a renewed bollard pull test may be
required.
3.3.6.3 For the towing winch and towing lines lbe
following should be available: ·
Certificate and particulars for the towing winch
stating manufacturer, type, maximum halding and
stalling pawer.
Certificates far main and spare towing wire ropes,
stating manufacturer. diameter of r~pe, length,
construction, naminal tensile strength af wires,
breaking strength.
A log far the towing lines, giving the following
information on each rope;
date taken in use,
records of inspection,
date of renewal of end sockets or other end
connections and
report on damage to the rope.
Certificates for shackles, rings and connecting
equipment.
3.3.7 Inspections and testing
3.3.7.1 Before departure an inspection of the towing
vessel and towed object including all parts of the 19wing
arrangement shall be carried out to canfirm compliance
with above stated requirements.
Functional testing of towing winch systems sball as a
minimum be carried out.
3.3.7.2 An inspection of the towing wire ropes shall be
perfonned. At least the first 50 metres of the towing
wire should be streamed for inspection.
1
DET NORSKE VERITAS
January 1996
Rules for Marine Operations
Page 12 of 14
Pt.2 Ch.2 Towing
3.3.7.3 The towing line shall not be used if;
the reduction of towline strength due to wear,
corrosion and broken wires ~xceeds 10 % and
there are severe kinking, crushing, or other
damages resulting in distortion of the rope
structure.
End sockets or other end connections should nonna1ly
Dot be older than 2 years, depending on the extent of use
(wear and tear).
Guidance Note
The low line should be subject for special evaluations if number of
broken wires over a length of 7 times the tow line diameter exceeds
6% of total number of wires In the tope, If significant wear of outer ·
layer of wires are found or if the tow line Is found significanUy
corroded.
Guidance Note
Special attention should paid 10 the connection of end sockets.
tal
)
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.2 Towing
January 1996
Page 13 of 14
4. TOWlNG OPERATIONS
4.1 TOWOUT
4.1.4 Towing manual
4.1.1 Tow out criteria
4.1.1.1 A tow out criteria sball be established for all
towing opemtions.
A tow out criteria of Beaufort force 5 or better for the
coming 24 bours is normally acceptable.
Based upon evaluations of tow out route, type of tow
and tow arrangement other tow out criteria may he
4.1.4.1 A towing mIlDuai shall be prepared and
distributed to key personnel. The tow master sball
familiarise himself with the towing procedure and
briefed about essential information in the towing
manual (limitations, restrictions etc.), see also Pt.]
Ch.2 Sec.3.5.
4.1.4.2 The towing procedure shall normally contain
detailed information regarding;
accepted.
tow out cliteria,
Guidance Note
criteria for seeking shelter,
towing route,
ports/areas of shelter,
The Intention with the tow out criteria Is to allow time for
familiarisation with the low, and to ensure adequate distance 10
shore In case of adverse weather conditions.
estimated towing time (EID, ETA),
envjronmentallimitations w.r .t. structural
4.1.1.2 The tow out should take place with good
capacity of object, senfnstening, grillage etc .•
visibility. Due care should be given to effects of
snow. rain, fog, etc . . This is particularly relevant if
tow master is unfamiliar with the area. Assistance
f~om
local
~i1ots
contingency actions,
description of the ballast conditioD,
reporting routines for progress of the tow.
ETA, status, etc. ,
contact persons and telepbone numbers,
expected environmental conditions for the
intended towing route for tbe relevant season,
and
Procedures for departure and arrival as well as
calls at intermediate ports.
should be evaluated.
4.1.2 Weather forecast
4.1.2.1 Arrangements for receiving weather forecasts
at regular intervals prior to IlDd during towing shall be
made.
(\"III
\
4.1.2.2 Weather forecast requirements sball comply
with Pt.l Ch.2 Sec. 3. 2.
4.2 TOWING
4.1.3 Internal seafastening
4.2.1 Routing
4.1.3.1 All loose items shall be properly"sccured
andlor stowed. Items that may be. damaged by water
shall be adequately protected.
4.1.3.2 Securing of internal items weighing more than
4.2.1.1 The routing sball be chosen so that adequate
bottom clearance and sea room are available during the
towing. Considerations should be giv~n to
navigational accuracy, environmental conditions and
loads, motion characteristics of the unit. possible heel
5 tonnes shall be verified by calculations according to
and
)
~)
trim effects, towing force. etc.
2.3.
4.1.3.3 Internal seafastening by means of steel wire
ropes, clamping devices, etc .• may be accepted for
securing smaller items such as piping, valves, etc.
4.2.2 Towingcleamnces
4.2.2.1 The tow should normally be routed so that a
minimum uoderkeel clearance of 5 metres for barge
and tug is obtained. Clearances less thaa 5 metres
sball be evaluated in eacb case.
DET NORSKE VERITAS
'.
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•
January 1996
Rules for Marine Operations.
Pt.2 Ch.2 Towing
Poge 14of14
4.2.2.2 The combination of bollard pull and towline
length should be so that a clearance of at least 5 metres
between towline bight and seabed i. rosintained.
4.2.2.3 The widtb of the towing route sbould
normaIly be at least three times the widtb of the tow.
Narrow cbanaels sbould be passed in with good
visibility •
4.2.3 Towing procedures
4.2.3.1 The tow sball not commence uoder more
adverse environmental conditions than specified by the
operational or characteristic design criteria.
4.2.3.2 During normal operation, the le"gth of the
)
towing line should be adju.ted at regular interval. to
avoid cbafing at the stem rail.
4.2.3.3 The crew of the towing vessel(s) and the
boarding crew or permanent crew for the towed object
shall be familiar with the equipment and installations
which may be used during the voyage. A
demonstration of the operation of bilge and ballast
systems, anchoring arrangement, etc. on the towed
object may be required before departure.
4.2.3.4 Slack tanks sbould be avoided. If used, it
should be verified that the specified slack tanks will
not jeopardise the stnbility or strength of the barge.
)
4.2.3.5 10 order to avoid slamming and improve
seakeeping it is recommended tbat the towed barge is
trimmed minimum 0.005 times barge length by stem,
and ballasted to a draft at bow of minimum 0.15 times
barge depth.
4.2. 3.6 For large tows or towing close to shipping
lanes the use of a guard ship to prevent other vessels
and objects fromjeopardi.ing tbe tow sbould be
considered.
4.2.3.7 For towing in areas with high traffic density
an escort tug should be available to assist in case of a
break down <;>f the rosin tug.
The presence of a riding crew on the barge may also be
relevant in such waters to pick up an towline. or
release the anchor, in case of towline failure.
)
DET NORSKE VERITAS
RULES FOR
PLANNING AND EXECUTION OF
MARINE OPERATIONS
PART 2 : OPERATION SPECIFIC REQUIREMENTS
I.
)
()
PART 2 CHAPrER 3
SPECIAL SEA TRANSPORTS
JANUARY 1996
SECTIONS
)
1. IN1RODUCTION. .. .. ... ...... ............... ... .. ... .... . ..... ... ....... .. .. .. . .. .. .. ...... .. .... .. ...... .. ...... ..... ...... . ......4
2. SlllP TRANSPORTATION ... .. ..... .. ..... . .. ..... . . . ......... . ..... , .. .... ....... . ...... .. .. . .. . ...... .... ...... ...... . ........ 5
3. MULTI BARGE TOWING ..... .. .. .. .... ... .. .............. .... ....... .. .... .. .. ........ . .. . ...... ... ..... .. .. .... . ..... .. .. .... . 7
4. SELF FLOATiNG TOWING ... . . .. . . .... ....... .... . ... .. .. . ....... ...... .. .......... .... .. ........ ...... .. .......... . . ...... .. 10
5. REAVY liFT CARRIERS . .. . .... . . ... .. .............. ..... .. . ....... ...... ........ ........ .. .. .... .. . . ....... ..... .. .......... . 12
<.J
}
DET NORSKE VERITAS
Verilasveien I , N-1322 Hevik, Norway Tel. : +47675799 00, Pax.: +47675799 11
CHANGES IN THE RULES
This is the first issue of the Rules for Planning and
Execution of Marine Operations, decided by the Board
ofDet Norske Veritas Classification A1S as of December
1995. These Rules supersedes the June 1985, Standard
for InsuJ!lDce Warranty Surveys in Marine Operations.
These Rules come into force on 1st of January 1996.
This chapter is valid until superseded by a revised
cbapter. Supplements to this chapter will not be issued
except for minor amenliments and an updated list of
corrections presented in the introduction booklet.
Users are advised to check the systematic index in the
introduction booklet to ensure that that the chapter is
current.
('
)
J
)
)
€I Det NQrake Veritaa
Computer 1)ipcsetting by Det Norske Veriul
Printed in Norway by the Det NOI'8k:e Veritu lanwuy 1996
1.96.600
Rules for Marine Operations
Pt.2 Ch.3 Special Sea Transports
January 1996
Page 3 or 13
CONTENI'S
o
I.
INTRODUCTION ••..•...•••. ••••.. .. ......•••....• 4
4.
SELF FLOATING TOWING ................... 10
1.1
GENERAL ....•..•.............•.............•........ 4
I. 1.1 Application .............•...•. .. ••............. 4
4 .. 1
1.2
DEFINITIONS ...............•... , ................... 4
1,2.1 Terminology .......... .•....................... 4
2.
SlllP TRANSPORTATION ...••.•....•••.•...... 5
PLANNING AND PREPARATION ............ 10
4.1.1 Application ........... '" ......... ....... ..... 10
4.1.2 Planning ... ...................... ....... ... ... . 10
4.1.3 Stability afloat ............................... 10
4.1.4 Design loads .... .. ............. . .... ... ' " .... \0
4.1.5 Buoyancy ..................................... \0
4.1.6 Hydrostatic loads ....... .. ...... ........ .... . 10
4.1.7 Other loads ...................... ..... ... ..... 10
4.1.8 Structural design ca1culations .............. 10
2.1
PLANNING AND PREPARATIONS ... ......... 5
2.1.1 Application ................... .......... ....... 5 .
2.1.2 Planning .•.................. . ................... 5
2.1 .3 Documentation .......... ... ... .. . ......... .... 5
2. I. 4 Design loads ...... .•.. ......................... 5
2.1.5 Structural design .................... •... ...... 5
2.1 ,6 ........ .. ........................................ 5
2.1.6 Scarastening ................................... 5
2. I. 7 Equipment ............... ......... .............. 5
4.2
TOWING EQUIPMENT .... ............... ....... \0
4.2.2 Systems and equipment. ......... .... ..... .. 1\
)
)
2.2
OPERATION ... ............. ...... ... .. ... ... ........ 5
2.2.1 Operational aspects ........................... 5
2.2.2 Transport procedure ..............•...... .•. .. 6
2.2.3 Inspection .... ....... ... ... ....... .. .... ........ 6
3.
MULTI BARGE TOWING....................... 7
3.1
PLANNING AND PREPARATIONS ............ 7
3.1.1 Application ............... ..... ..... .. ......... 7
3.1.2 Planning ......................... ............... 7
3.1.3 Stability afloat. ................................ 7
3.1.4 Design loads .................. .. ............... 7
3.1.5 Skew loads .....•................................ 7
3.1.6 Structural design verification ............... 7
3. I. 7 Barge supports ................ .. .......... .... 7
3.1.8 Scafastening .................. ... ...... ..... ... 8
\
3.2
TOWING EQUIPMENT .... ..... ...... ..... ....... 8
3.2.1 Barges ......................... .. .. ........ ..... 8
3.2.2 Barge ballasting systems ... ... .. ... .......... 8
3.2.3 Towing arrangement and equipment ....... 8
3.2.4 Towing vessels ..... ...... ........ .............. 8
3.2.5 Navigational equipment ..................... 8
3.3
TOWING OPERATIONS .......................... 9
3.3.1 Operational aspects ......... .................. 9
3 .3.2 Clearances ................. ...... .. ..... ....... 9
3.3.3 Survey of towing route ...................... 9
3.3.4 Monitoring .... ........ ....... .................. 9
4.2.3 Navigation equipment ........... . .......... 11
4.2.4 Navigalionallights and sbapes .. .......... 1\
4.3
TOWING OPERATIONS ................ .... ..... ll
4.3.1 General ........................................ 1\
4.3.2 Rubber diapbrngms ............... .... ....... 1\
5.
BEAVYLlFTCARRlERS ................... ... U
5. 1
PLANNING AND PREPARATIONS .......... 12
5.1.1 Application ................... ................ 12
5.1.2 Planning ....... .. .............................. 12
5.1.3 Stability afloat .......................... .. ... 12
5.1.4 Design loads ... .. ........................ .. ... 12
5.1.5 Motions during transit. •.......... .......... 12
5.1.6 Structural design calculation ............... 12
5.1.7 Cribbing and guides ......................... 12
5.1.8 Self propelled carrier..... ..... .. ... ... .. .... 12
5. 1.9 Documentation ............................... 13
5.2
OPERATIONAL ASPECTS ...................... 13
5.2.1 Transport procedure .............. ... ..... ... 13
5.2.2 On and off loading ............ .... ..... ..... 13
5.2.31nspections and testing ........ ..... ......... 13
DEI' NORSKE VERIrAS
n
January 1996
Rules for Marine Operations
Pt.2 Ch.3 Special Sea Transports
Page 4 of 13
1. INTRODUCTION
1.1 GENERAL
Unit: The assembled configuration of transport barges
and object to be transported.
1.1.1 Application
1.1.1.1 Pr.2 Ch.3 SpeciaI Sea Transports, give specific
requirements and recommendations for transportations
ooboard conventional ship, for multi hull ,towing. self
floating and self propelled carrier transports.
Guidance Note
Requirements and recommendations for single vessel and barge
towing operation are given In Pt.2 Ch.2. Requirements and
rCMlmmendations for transit and positioning of Mobile Offshore
Units are given in Pt.2 Ch.7
1.1.1.2 General requirements and guidelines for ship
transportation, multi hull towing, self floating and self
propelled carrier transports are given in Pr.I of these
Rules. This chapter iscomplementaIy to Pr.I.
1.1.1.3 Conditions for using these Rules are stated in
Pr.D Ch.I Sec.I.2.
1.2 DEFINITIONS
1.2.1
Tenninolo~
1.2.1.1 Definitions of terms ate included in the Pr.D
'ch.I. Terms considered to be of speciaI importance for
this chapter are repeated below.
)
Heavy lift carrier: A sub.mersible barge or vessel
carrying heavy object on deck. The objects are
loaded/off-loaded the carrier by float on/float off
operations.
Heavy lift carrier transports: Transfer at sea from one
location to another of an object by a heavy lift carrier.
Object -The object handled during the marine operation,
typically a module, deck structure, jacket, sub sea
structure, pipes, other equipment.
Multi barge rowing: Transfer at sea from one location to
another of an object resting on two or more barges by
use of tugs.
Selffloating rowing,' Transfer at sea from one location
to another of an object supported by its own buoyancy
and pushed/ pulled by tugs.
)
Ship transportation: Transfer of an o~ject at sea from
one location to another of an object onboard a
coDventional vessel or supply vessel.
DET NORSKE VERITAS
)
January 1996
Rules for Marine Operations
Pt.2 Ch.3 Special Sea Transports
PageS ofl3
2. SHIPTRANSPORTATION
2.1 PLANNING AND PREPARATIONS
2.1.6 Seafastening
2 .1.1 AppliCation
2.1.6.1 Seafastening should primarily be arranged with
welded stoppers or chain. Seafastening with wire ropes
2.1.1.1 This section applies for transportation of heavy
objects on deck, or in cargo holds of conventional
is normally not acceptable for items weighing more than
1 tonne.
vessels, supply vessels elc.
'0)
,
)
Q) ,
2.1.6.2 Ifseafastening is arranged with chain tensioner,
special considerations shall be mode to possible skew
loads due to uneven pretensioning. undetermined
2.1.2 Planning
2.1.2.1 Planning ofspecial ship transportation's sball
as applicable comply with Pt. ] CiI.2. Sec.2.
2.1.2.2 Stability requirements shall be according to
Pt.] CiI.2 SecA.
seafastening arrangements.
The design loads for chains should be multiplied with a
skew load factor not less than L5 if skew load effects are
not calculated.
2.1.6.3 Characteristic strength for chain used in
2.1.3 Documentation
Sell-fastening may be based on certified MBL, and
material factol'S according to Pt.] Ch.4 SecA.
2.1.3.1 The plaoned sea transportation shall be
Reductions in MBL due to bending sball be considered.
described by procedures and drawings. Struc!ural
strength shall be documented ·by design calculations,
certificates, approval statements etc.
2.1. 7 Equipment
A procedure covering the relevant aspects of the sea
transportation operation should be prepared, see 2.2.2.
2.1.7.1 General requirements are given in Pt. 1 Ch.2.
Sec.5.
2.1.3.2 Before the start of operations weight reports,
certificates, test reports and
classifi~tion
documents fOf
equipment involved shall be presented, as applicable.
2.2 OPERATION
2.2.1 Operational aspecls
2.1.4 Design loads
2.1.4.1 Characteristic environmental conditions and
loads shall comply with Pr.I Ch.3.
2.1.4.2 Simplified accelerations may be calculated
according to DNV Rules for Classification, Steel Ship,
accelerations for heavy qbjecls.
2.1.4.3 Characteristic loads shall be combined, factored
and analysed according to Pt.I ChAo
2.2.1.1 General operational
Pt. I CIz.2 Sec.3.
requiremen~ are given
in
2.2.2' Transport procedure
2.2.2.1 A transport procedure sball be prepared and
distributed to key personnel. The master shall be briefed
regarding essential information in the transport manual
(design limitations, restrictions etc.), see. also Pt.I Ch.2
Sec. 3. 5.
2.1.5 Structural design
2.1.5.1 Structural design calculations shall comply with
Pt.] CI~4 .
2.1.5.2 Load distributing grillage elements may be
required to avoid local overloading of deck structures.
)
DEI' NORSKE VERITAS
n
Rules for Marine Operations
Pt.2 Ch.3 Special Sea Transports
January 1996
Poge 6 of 13
2.2.2.2 The transport procedure should contain detailed
information regarding;
route,
ports/areas of sheller,
estimated transport time, ETD and ETA,
environmental limitations w.r.t. structurnl
capacity of object, seafastening, grillage etc.,
contingency actions,
reporting routines for progress, ETA. status, etco,
.cantlel persons, including key personnel at
receiving site, and telephone numbers, and
2.2.3 Inspection
)
2.2.3.1 Seafastening arrangements shall be regularly
inspected during the voyage. Special allention shall be
given to seafastening arrangements with chain tcosioner
or wire/turnbuckles.
Procedure for corrective actions and reporting shall be
developed.
)
)
DET NORSKE VERITAS
n
Rules for Marine Operations
Pt.2 Ch.3 Spe<:ial Sea Transports
January 1996
Page 7 of 13
3.
MTILTIBARGETO~G
3.1 PLANNING AND PREPARATIONS
3,1.5 Skew loads
3.1.1.1 This section applies to transport of heavy
objects on mUltiple barges or huJls.
3.1.5.1 Skew loads are loads due to fabrication and
operation tolerances, offset, inaccuracy. etc., and shall
be considered for the transported object. barge supports,
etc.
3.1.2 PlarutUng
3.1.5.2 The foUowing skew load effects should be
considered;
3.1.1 Application
,
))
3.1.2.1 Planning of multi barge towing shall comply
with Pl.] CiI.2 Sec.2.
3.1.3 Stability afloat
3.1.3.1 General requirements to stability are given in
Pt.] CiI.2 Sec.4.
3.1.4 Desill" loads
3.1.4.1 Characteristic loads for multi barge towing
shali" comply with Pl.] Ch.3.
fabrication tolerances for the traosported object
and for the barge supports,
fabrication tolerances for the barges,
vertical offset of the traosported object for each
support condition,
barge heel and trim,
movement of buge centre of buoyancy, gravity
aod flotation relative to draught and ballast
configuration,
inaccurate positioning of barges relative to the
traosported object's supports,
deformation of the transported object aod the
barges including the possible introduction of
horimotalloads and
other relevant effects.
3.1.4.2 A separate aoalysis may be necessary in order
to assess support loads acting 00 the individual barge
supports.
3.1.6 Structural design verification
3.1.4.3 Characteristic loads shall be combined, factored
and analysed .ccording to Pl. ] Ch.4.
3.1.6.1 Structural design verification of multi barge
towing operations shall comply with Pl. ] Ch.4.
Guidance Note
An advanced analysis taking proper"account of the barges IndivIdual
responses Is nonnally required.
.
3.1.4.4 At least one of the accidental load cases shall
considered collapse of one arbitrary grillage support
element.
3.1.6.2 The barge ballaSting condition should be .
optimised to ensure favourable load distribution in the
barges aod the traosported object.
3.1.6.3 Strength verification of local support points in
grillage and transported object shall be performed.
Guidance Note
By ~grillage support ejement" are meant stiffener, plate field, girders
etc, that may be damaged during the operation. Elements exposed
may be fdenlifted from relevant acCidental scenarios. Collapse of an
element may be considered by neglecting the element in the
structural design analysis.
3.1.4.5 Force distributions and deflections in the
transported object and in the barges shall be determined
and considered in the design calculations, see also Pt. J
Cld Sec.3.7
3.1.7 Barge suppnrts
3.1.7.1 Flexible support system (crushing tubes, lend
plates, wedge arrangement, etc.) shall h'avc sufficient
capacity to account for the deflections of the deck aod
the barges during traosportation conditions.
The flexible support system shall be designed according
to • fuil to safe philosophy, i.e. the supports shall resist
an overloading without total collapse.
3.1.7.2 To avoid progressive deflections due to
dynamic loading of the supports, • "fall back" securing
arrangement should be considered, see also 3.1.8.2.
)
DEf NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.3 Special Sea Transports
January 1996
Page 8 of 13
3.2.4.2 The towing Heet should have the capacity and
3.1.8 Seafastening
be arranged so that;
3.1.8.1 The transported object shall be secured by
seafastening structures with sufficient strength to
withstand design loads in both horizontal and vcrtical
direction during the towing operation.
3.1.8.2 The seafastening structures shall possess
sufficient flexibility to accommodate the relative
deflections and avoid overstressing the transport object
or the barges.
3.1.8.3 Ifseafastening ·is provided by means of wedges,
. in fill pieces or similar, these shall be secured by tack
welding. Securing of these items shall take place as soon
as possible after completion of the load transfer
)
operation.
the unit can manoeuvre within specified
tolerances during all stages of -the tow (this is
normally best achieved by utilising a number of
high manoeuvrability type tugs),
keep the barges loaded with the transported object
at zero speed during the design environmental
condition and
maintain control over the unit in all phases of the
operation with lOBS of thrust fro:m one tug.
3.2.4.3 SuffiCient tug capacity shall be present for
towing/positioning. The towing resistance should be
determined by considering the following effects;
~urrent
velocity,
towing speed,
wave resistance (if applicable),
wind velocity and
interaction of between propen~r race and the
multi barge unit, see also Pt. 2 Ch.2 Sec.3.3.2.
3.2 TOWING EQUIPMENT
3.2.1 Barges
3.2.4.4 Required tug capacity shall be based on
3.2.1.1 Barges for multi barge towing shall comply
with requirements in Pt.2 Ch.2 Sec.3.2.
3.2.2 Barge ballasting systems
characteristic environmental conditions, see Pt.! Ch.3
Sec. 2. Wind velocities less than 20 mlsoc shall nol be
used.
3.2.4.5 Required tug capacity in "hold" area or
3.2.2.1 The ballasting system on each barge should be
capable of redistributing loads due to Hooding of any
one compartment in the barge.
conditions shall be based on characteristic environmental
conditions for a period not less than 30 days, see Pt.]
Ch.3 &c.2. Required tug capacity in a hold area shall
also consider failure of one tug as a PLS case.
3.2.2.2 Spare parts (blind Hanges, leak mats, welding
equipment, etc.) should be available onhoard the barges
)
in case of leakage. Regular inspections of air pressure
and water level in the barge tanks should preferably be
carried out during the transportation.
3.2.5 Navigational equipment
3.2.5.1 The navigation of the towed object shall he
monitored by means of two independent -systems.
3.2.5.2 The primary system should bave all critical
3.2.3 Towing arrangement and equipment
3.2.3.1 The towing arrangements and attachments sball
functions duplicated and tested before commencement of
the towage.
comply with requirement. in Pt. 2 Ch.2 Sec. 3. 1
3.2.3.2 Facilities such .. barg.deck winches, hydraulic
3.2.5.3 The secondary system should be separate from
Ute primary system, both in principle and location. For
jacks, thrust stnIts, etc" shall be considered in order to
assist with accurate positioning of the barges e.g. under
cODstruction pillars, during mating. etc.
inshore towing operations, the use of theodolite
triangulaiion would be an example of a typical
ac~eptable secondary system.
Guidance Note
Siinultaneous operation of winches and tugs should be carefully
evaluated. Tugs and Winches should preferably be used separately _
3.2.5.4 At critical phases of the towage, such as
departing from a mOQring location, towing in narrow
waters and arrival, both systems should be used as a
cross reference to another.
3.2.4 Towing vessels
3.2.4.1 General requirements for towing vessels are
given in Pt.2 Ch.2 Sec.3.3.
DET NORSKE VERITAS
..
Rules for Marine Operations
Pt.2 Ch.3 Special Sea Transports
January 1996
Pnge 9 of 13
3.2.5.5 For towing in Darrow channels and for accurate
positioning. the compatibility of the navigation
equipment onboard the survey ship and onbonrd tbe lead
tug should be verified by tests carried out prior to
commencing a towage. The latest edition of available
sea charts should be used.
3 .2.5.6 If the navigation equipment is installed on
board the towed object and the towing operation is
conducted from here, compatibility and tests as per
3.2.5.5 apply.
3.3.4 Monitoring
3.3.4.1 The following should be considered to be
monitored manually or by monitoring .y.tems during the
towing operation;
water level. air pressure, etc., for buoyancy tanks
position and orientation relative to the towing
channel
draught, heel, and trim
underkeel clearance and
environmental conditions.
3.2.5.7 If the towed object floats in a very low
position, the fitting of an Emergency Position Indicating
Radio Beacon (EPlRB) should be considered.
3.3 TOWING OPERATIONS
3.3.1 Operational aspects
3.3.1.1 Ge.neral operational requirements are give,n in
Pt. } CiI.2 Sec.3.
3.3.2 Clearances
3.3.2.1 The towing route should normally have
sufficient water depth to provide a minimum net
underkeel clearance of 5 metres, to the deepest part of
the towed object. Clearances less than 5 metres shall be
evaluated in each case. This requirement applies for the
whole width specified in 3.3.2.2.
)
The oet clearance shall include deductions for;
motions,
swell,
tolerance on bathymetry and
tide variations.
3.3.2.2 The width of the towing route should normally
not be less than the breadth or length of the towed object
plus 100 metres, i.e. 50 metres at each side of the object.
3.3.2.3 Clearance to shore in holding areas should not
be les. than 2 nautical miles.
3.3.3 Survey of towing route
3 .3.3.1 For large tows or towing in restricted waters a
special bottom survey of the intended towing route and
receiving site should be carried out. The survey should
cover an adequately wide route to ensure that no
unknown hn:mrds exist which might hamper the low.
Normally a survey using side scanning sonar will be
adequate.
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.3 Special Sea Transports
January 1996
Page 10 of 13
4. SELF FLOATING TOWING
4.1 · PLANNING AND PREPARATION
4.1.6.2 The characteristic hydrostatic loads should be
based on the most severe draught or hydrostatic head for
the individual structure or compartment.
4.1.1 Application
4.1.1.1 This section applies to towing of objects such
as gravity base structures, jacket substructures, offshore
towers, etc. supported by their own buoyancy and
pushed/pulled by tugs.
4.1.6.3 Buoyant compartments exposed to external
water pressure should norma1Jy be designed to withstand
hydrostatic loads for all relevant draughts without
pressure compensation by means of air pres~risatioD.
Guidance Note
Reference Is also made to VMO Guideline 1.1, November 1989,
Mooring and Towage of Gravity Base structures.
4.1.7 Otherloads
4.1.2 Planning
4.1. 7.1 All other significant loads occurring during the
operations should be considered. In particular, the
following effects should be considered during towing;
4.1.2.1 General requirements to preparation and
planning are given in Pt. 1 Ch.2 Sec.2.
wave slamming loads
vortex shedding due to aero- and hydrodynamic
drag forces,
intera<;:tion between the towed object and the
4.1.3 Stability afloat
4.1.3.1 General requirements to stability are given in
Pt.1 Ch.2 SecA.
propeller race, and
increased draught due to interaction betweeo the
seabed and the towed object, and
channel effects in Darrow passages.
Special considemtions should be givep to local load
4.1.4 Design loads
4.1.4.1 Characteristic loads shall be established in
accordance with Pt. 1 Cil. 3.
4.1.4.2 Characteristic loads shall be combined, factored
and analysed according to Pt.1 ChA.
)
effects of slamming, sloshing and increased weight on
deck for structures with low free board.
4.1.7.2 Auxiliary and permanent buoyancy tanks,
similar buoyant structures and attachments to the towed
object should be designed to withstand the buoyan~y
forces presented in 4.1.6, as well as environmental
loads, slamming loads, etc .
4.1.5 Buoyancy
4.1.5.1 The buoyancy of the self-floating object shall
be estimated on the basis of an accurate geometric
model. The buoyancy shall be estimated for all relevant
draughts. The position of the centre of buoyancy shall
be estimated accordingly.
4.1.8 Structural design calculations
4.1.8.1 Structural design calculations sball comply with
Pt.1 ChAo
The final buoyancy estimate should take place when the
final geometry of the object is established.
4.2 TOWING EQUIPMENT
4.1.6 Hydrostatic loads
4.2.1.1 Towing vessels sball comply with requirements
in 3.204.
4.1.6.1 Hydrostatic loads due to external water pressure
on submerged structwes or internal water pressure in
water filled compartments should be considered.
4.2.1.2 Towing arrangements and attachments sball
comply with requirements in Pt.2 Ch.2 Sec.3.1 .
)
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.3 Special Sea Transports
January 1996
Page 11 of 13
4.2.2 Systems and equipment
4.2.2.1 Systems and equipment sball be designed,
fabricated, installed, and tested according to Pl.} CIr.2
See.s.
4.2.2.2 Submerged towing brackets ,ball be designed to
avoid openings to sea in case of overloading the towing
bracket.
4.2.3 Navigation equipment
4.2.3.1 The requirements in 3.2.5 apply.
4.2.4 Navigational lights and shapes
)
4.2.4.1 The requirements in Pl.} Ch.2 See.5.2 apply.
4.3 TOWlNGOPERATIONS
4.3.1 General
4.3.1.1 The requirements in 3.3 apply
4.3.2 Rubber diaphragms
4.3.2.1 Rubber diaphragms sball bave sufficient
streogth to withstand internal and external water hend or
air pressure including loads due to temperature cbanges
after assembly. The rubber diaphragms shall also be
capable of withstanding relevant bydrodynamic drag and
inertia forces during towing.
)
4.3.2.2 Rubber diaphragms should be protected against
wear, heat, and frost after assembly.
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DET NORSKE VERrrAS
()
Rules for Marine Operations
Pt.2 Ch.3 Special Sea Transports
January 1996
Page U oC13
5. HEAVY LIFT CARRIERS
5.1 PLANNING AND PREPARATIONS
5.1.5 Motions during transit
5.1.1 Application
5.1.5.1 The motions should be determined in
accordance with Pt. 1 Ch. 3.
5.1.1.1 ·Thi. section applies to objects being
tl'lUlSported on heavy lift carriers.
)
5.1.2 Planning
5.1.5.2 For heavy lift earrier with an optimised
motion characteristic/low GM value, special
considerations should be given to the effects of wind
heeling.
5.1.2.1 Planning and preparations shall comply with
Pt.1 Ch.2 Sec.2.
5.1.5.3 Heave induced roll motion may occur if there
are large changes in waterplane area with the draught.
For such a s~tuation a special analysis andlor model
test. sbould be performed to quantify this effect.
5.1.3 Stability afloat
5.1.3.1 General requirements to stahility are given in
Pt.] Ch.2 SecA.
)
5.1.6 Structural design calculation
5.1.6.1 Structural desigo calculations sball comply
with Pt. 1 ChAo
5.1.4 Design loads
5.1.4.1 Cbatacteristic loads for heavy lift traosporls
shall comply with Pt. 1 Ch.3.
5.1.4.2 Traosportation with .elf propelled heavy lift
carriers having a redundant propulsion system
experience not more than 50 % reduced thrust in case
of any single failure, may be designed for n limited
wave beading range. The range should not be taken
less than £lO degrees from head seas.
5.1.6.2 Local strength verification of transported
object and earrier at support points shall always be
performed.
5.1.7 Cribbing and guides
5.1.7.1 The size of the cribbing should be adequate to
account for possible inaccuracies in positioning of
cargo, placement of guides, etc.
5.1.4.3 Characteri.tic loads .hall he combined,
faelored and analy.ed according to Pt.] ChAo
5.1.7.2 The placing of cribbing .hall be such that no
overloading of car~o or vessel will occur.
5.1.4.4 Cargo haoging over the sides of the earrier
should be particularly considered for;
5.1.7.3 The guide posts shall be desigoed to absorb a
relevant amount of energy, see Pt.] Ch.2 Sec.5A.
wave slamming loads,
uplifting,
drag loads,
influence on motions, and
'-.
5.1.7.4 The guide posts should normally extend 2
metres above the water plane at deepest draught. The
guide post ,hall be clearly visible duriog the float
on/float off operations.
influence on stability.
5.1.4.5 If other vessels such as barges are to be
transported by the carrier, relevant contingencies 00
weight should be included to account for effects such
as residual ballast water etc.
5.1.8 Self propelled carrier
5.1.8.1 General requirements are given in Pt. ] Ch.2
Sec. 5. 2.
5.1.4.6 Effects of friction .hall be con.idered in
accordaoce with Pt.1 CIr.3 Sec. 3.2.
5.1.8.2 All particulars regarding strength, stability
afloat, and all systems and equipment should be within
the requirements of the vessel's Classification Society.
DET NORSKE VERITAS
o
Rules for Marine Operations
Pt.2 Ch.3 Special Sea Transports
January 1996
Page 13 of 13
5.1.9 Documenlation
5.1.9.1 The documents as listed in Pt. 1 Ch.2 8ec.2.2
as relevant for self propelled vessels shan be provided.
5.2 OPERATIONAL ASPECTS
5.2.1 Transport procedure
5.2.1.1 A transport pro~ure shall be prepared and
distributed to key personnel. The master .hall be
briefed about essential information in the transport
manual Oimitations, restrictions etc.), see also Pt.I
Ch.28ec.3.4.
)
5.2.1.2 The transport proeedure should contain
delailed information regarding;
))
load onlload off proeedure,
route,
ports/ll!e8S of .helter,
estimated transport time, ETD and ETA!
environmental limitations w.e.t. structural
capacity of object, seafastening, grillage
contingency actions,
~.,
reporting routines for progress, ETA, status,
ele. ,
contact persons and telephone numbers.
expected enviroD.Ii:lental conditions for the
intended route for the relevant season and
proeedures, including procedures during
departure imd arrival as well as call. at
intermediate ports.
)
5.2.2 On and off loading
5.2.2.1 Limiting environmental criteria sball be
established for the flo.t on /flo.t off operations.
5.2.2.2 A survey of the lo.ding/unloading site should
be performed to ensure sufflcieot waler depth during
the loading/unloading operalion.
)
5.2.2.3 The minimum clearance belweeo the cargo
and the top of !be cribbing should be 0.5 melres during
float on/float off, considering motions, tolerances and
deflections.
5.2.3 Inspections and testing
5.2.3.1 Daily inspection of the cargo and seafastening
sbould be performed during the voyage.
)
DEI" NORSKE VERITAS
()
RULES FOR
PLANNING AND EXECUTION OF
MARINE OPERATIONS
PART 2 : OPERATION SPECIFIC REQUIREMENTS
)
o
PART 2 CHAPfER 4
OFFSHORE INSTALLATION
JANUARY 1996
SECTIONS
I. INTRODUCTION ............................................ .. .............. .. .... .. ......................... ...................... 5
2. LOADS .................. ...... .. ...................................................................................................... 7
. )
3. LAUNCHING ........................................................... .... .. .... ................ .......... .. .... ... .. ..... ........ 8
4. UPENDING ......................................................................................................................... 12
5. POSmONING AND SETIlNG .................................................................................. : .............. 14
6. PIUNG AND GROUTING ....................................................................................................... 17
)
)
DET NORSKE VERITAS
Vcritasveien I, N-I322 H""ilc, Norway Tel.: +4767579900, Fax.: +4767579911
n
CHANGES IN THE RULES
This is the first issue of the Rules for Planning and
Execution of Marine Operations, deCided by the Board
of Det Norske Veritas Classification AlS as of December
1995. These Rules supersedes the June 1985, Standard
for Insurance Warranty Surveys in Marine Operations.
These Rules come into force on ,lst of January 1996.
This chapter is valid until superseded by.3 f.evised
chapter. Supplements to this chapter will not be.iss!led
except for minor amendments and an updated list of
corrections presented in the introduction booklet.
Users are advised to check the systematic .index in the
introduction booklet to ensure that that the chapter is
current.
(
)
)
)
Oct Norske Veri168
Computer Typesetting by Det Nors1:::e VerilaB
Printed in Norway by the Det Notll1:::c Veritas January 1996
@
1.96.600
January 1996
Rules for Marine Operations
Pt.2 Ch.4 Offshore Installation
()
Page 3 of18
CONfENTS
I.
INTRODUCTION .................................. 5
4.
UPENDING ........ .. ............................... U
1.1
GENERAL ........ .. .................................. 5
1.1.1 Application .................................... 5
4.1
INTRODUCTION .................................. 12
4.1.1 Application ................................... 12
4.1.2 General considerations ...................... 12
1.2
DEFINITIONS ........................... .... ........ 5
1.2.1 Terminology ......... .. ........................ 5
4.2
LOADCASES AND ANALYSIS OF FORCESI2
4.2.1 General ................................ ·........ 12
4.2.2 Loadcases and force distribution ..... ... .. 12
4.3
STRUC11JRES ...................................... 12
4.3.1 General ........................................ 12
4.3.2 Stability afloat ...................... ...... .... 12
4.3.3 Structural slrcngtb ........................... 13
4.4
SySTEMS ........................ .. ................. 13
4.4.1 Ballasting and deballasting systems ....... 13
4.5
OPERATIONAL ASPECTS ...................... 13
4.5.1 General ...................................... .. 13
4:5.2 Monitoring of upending operations ....... 13
1.3
)
INSTALLATION SiTE ............................. 5
1.3.1 Survey ...... .................... .. ...... .. .... .. 5
2.
LOADS .... . .. ....... . . ..... ........................... 7
2. 1
ENVIRONMENTAL LOAbS ..................... 7
2.1 . 1 General. ....................................... . 7
2.1.2 Hydrostatic loads .......... .... ............... 7
2.1.3 Positioning loads .... ...... .. .. .... .. .... .... . 7
2.1 .4 Loads from soil ...................... . ...... .. 7
2.1.5 Other loads .................................... 7
0)
3.
LAUNCHING ....................................... 8
5.
POSITIONING AND SETTING ............... 14
3.1
INTRODUCTION ...... .. ........................... 8
3.1.1 Application ........ .. ........ .. ................ 8
3 .1. 2 General considerations ................... .... 8
5.1
INTRODUCTION .................................. 14
5.1..1 Application ................................... 14
5.1.2 General considerations ...................... 14
LOADCASES AND ANALYSIS OF FORCES 8
3.2.1 GeneraL ........................................ 8
3.2.2 Loadcas~ and force distribulioD ..... .... .. 8
5.2
LOADCASES AND ANALYSIS OF FORCESI4
5.2.1 General .. .. : ................................... 14
5.2.2 Load cases and force distribution ......... 14
LAUNCHED OBJECT ............................. 9
3.3.1 General .................................... ..... 9
3 .3.2 Structural strength ............................ 9
5.3
STRUCI1JRES ...................................... 14
5.3.1 General ...... .. ................................ 14
.5.3.2 Stability afloat ................................ 14
5.3.3 On·bottom stability ...... .................... 14
5.3.4 Structural strcngth ........................... 15
5.4
SYSTEMS .............. .. ........................... 15
5.4.1 Ballasting and deballasting system .. , ..... 15
5.4.2 Mooring and towing system ............... 15
5.5
DOCKING ................. ........ .... .............. 15
5.5.1 General ........................................ 15
5.5.2 Vertical docking ............................. 16
5.5.3 Horlrontal docking ......................... . 16
5.6
OPERATIONAL ASPECTS ...................... 16
5.6.1 General ................ .. .... ...... ...... . ..... 16
5.6.2 Monitoring ...... .. ........................... 16
3.2
3.3
0")
3.4
Q)
3.5
3.6
LAUNCH BARGE ............ : ..................... 9
3.4.1 General ........................................ . 9
3.4.2 Stability afloat ........ ........ .. .............. . 9
9
3.4.3 Structural strength ............................
,.
SYSTEMS AND EQUIPMENT .................. 10
3.5.1 Ballasting system ........ .................... 10
3.5.2 Power supply and flame cutting facilities 10
3.5.3 Launch devices and systems .......... .... . 10
3.5.4 Equipment arrangement ...... .. ............ 10
3.5.5 Inspection and tests .......................... 10
OPERATIONAL ASPECTS .......... .. .......... II
3.6.1 Preparations for Jaunching .... , ...... .. .... 11
3.6.2 Positioning of barge and object. .... ...... l1
3.6.3 Monitoring of launching operations ...... 11
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DET NORSKE VERITAS
()
Rules for Marine Operations
Pt.2 ChA Offshore Installation
January 1996
Page 4 of 18
6.
PILING AND GROUTING ....................• 17
6.1
INTRODUCI10N ................................ . 17
6.1.1 Application .................................. 17
6.1.2 General considerations ... ... ..... . ......... 17
6.2
OPERATIONAL ASPECTS .....................
6.2.1 Pile installation ..............................
6.2.2 Clearances ....................................
6.2.3 Followers ........................ .... ........
6.2.4 Grouting .............. ................ ........
17
17
17
17
18
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DET NORSKE VERITAS
()
Rules for Marine Operations
Pt.2 Ch.4 Offshore Installation
January 1996
Page 5 of 18
1. INTRODUCTION
l.l GENERAL
Object: An offshore structure or parts thereof subjected
to one or several of the offshore installation operations
as listed iill . I . I.3 and defiiled below.
1.1.1 Application
1.1.1.1 PI.2 ChA, Offshore Installation, provide
specific requirements and recommendations for offshore
installation operations particularly applicable for fixed
offshore structures such as jackets, offshore towers, and
gravity base structures. For installation of TLP's,
loading buoys and other floating structures, parts of this
)
chapter may be used where applicable.
1.1.1.2 General requirements and guideliiles iii PI. 1 of
these Rules applies to offsbon:: installation operations.
This chapter is complementary to Pt. I.
1.1.1.3 . PI. 2 ChA covers the followiilg iilstallation
operations;
of an object resting on a specially equipped launch
barge, the object's slide down the skid beams on the
barge and diving into the water until the object is free
"o.tiilg.
Upending: The activities necessary to upend a floating
ohject.
Positioning: The activities necessary to position an
object at a certain predeiermined location.
Setting: The activities necessary to set-down an object
on the seabed after positioning, including levelling, soil
penetration and suction (if applicable).
Piling: The activities necessary to seCure an object to
the sea bottom by driving piles into the sea bottom.
launchiilg,
upending,
positioning and setting down, and
piling and grouting.
Above installation operations are _defined
LAunching: An activity comprise cutting of seafastening
in 1.2.
1.1.1.4 Liftiilg aspects of the offshore iilstaIl.tion
Groutillg " The activities necessary for cementing the
void spaces between pile and pile sleeve after ·pile
driving or the provision of even foundation support for
an object placed on tbe sea bottom by injection of
cement under the base structure.
Liftillg : The activities necessary to lift or assist an object
operations are covered in Pt.2 Ch.5.
by crane.
i )
1.1.1.5 Operational .aspects related to execution of the
piling and grouting operations are covered in Sec. 6. For
piling and grouting operations from a structural strength
point of view reference shouid be ~de to Pt. I CII.4.
Guidance related to such aspects may also be found iii a
recognised codes or standards. e.g. Veritas Rules for
the Design, Constructi9n and Installation of Offshore
Stru,tures, 1977 iilcludiilg Appendix F: Foundation and
Veritas Technical Note for Fixed Offshore Installations,
Underbase Grouting of Gravity Structhres, TNA 303.
1.3.1.1 A bathymetric survey of the installation site
shoul4 be performed with sufficient accuracy for the
desigu of the operations listed iii 1.1.1.3.
1.1.1.5 Conditions for using these Rules are stated in
PI. 0 Ch.I Sec.l.2.
1.3.1.2 The soil parameters at the target area for
installation should be determined.
1.2 DEFINITIONS
1.3.1.3 The type and extent of site surveys should .be
determined in relation to type, size, design tolerances
and importance of the object to be installed and the
uniformity of the seabed. Obstacles both on and iii soil
strata should be revealed.
1.2.1 Terminology
1.3 INSTALLATION SITE
1.3.1 Survey
1.2.1.1 Definitions of terms are iilcluded iii the Pt. 0
CII.I. Terms considered to be of special impo~ce for
this chapter are repeated below.
DEf NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.4 Offshore Installation
January 1996
Page 6 of 18
1.3.1.4 In selecting tbe size of eacb area to be
investigated. sufficient tolerances should be included to
account fOfi
positioning errors during site investigation,
errors in navigation equipment used for
installation, and
realistic operational tolerances.
1.3.1.S The required measurement accuracy for
differential elevation measurements should he
considered. Possible sand waves and seabed movements
and possible seabed level cbanges caused by drilling
operations through templates sbould be investigated.
)
1.3.1.6 A seabed survey giving a qualitative description
of tbe batbymetry at tbe instnllation slle should be
carried out before the installation opemtion to prevent
obstacles such as boulders, anchors, ~ebris , etc., to
jeopardise tbe instnllation of tbe object.
Normally a scanning survey sbould be performed acme
time before the operation followed by a more detailed
survey shortly prior to tbe operation ,using a remotely
controlled vehicle or similar.
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DIIT NORSKE VERITAS
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January 1996
Page 7 or1S
Rules for Marine Operations
Pt.2 eh.4 Offshore Installation
2. LOADS
2.1 ENVlRONMENTALLOADS
2.1.5 Other loads
2.1.1 General
2.1.5.1 When relevant, consideration should be given
to special loads such as;
2.1.1.1 Environmental loads should be determined in
accordance with Pt. 1 Ch.3.
2.1.2 Hydrostatic loads
()
2.1.2.1 Hydrostatic pressure loads due 19 external water
pressure op. submerged structures or intem;ll water
pressure in water filled compartments should be
considered.
2.1.2.2 The cbaracteristic value oftbe hydrostatic
pressure loads shquld be determined for the most severe
hydrostatic head occurring during installation of the
object.
slannning loads,
loads due to pressure differences -in independent
skirt compartments during the soil penetration
phase,
loads in the object due to transfer of ballast,
loads due to installation toleran.ces. an~
crane loads during crane assisted
upending/positioning.
The characteristic values of the above loads may be
determined considerin.g the following operational
aspects;
limitations related to the strength of the object
and the soil penetration rale,
capacity of the skirt water evacuation system.
whether "suction" is used or not, and
ballasting arrangement and rate.
2.1.3 Positioning loads
2.1.3.1 Positioning loads related to translation and
rotation of the object during launching, positioning, and
setting should be considered.
2.1.3.2 The cbaracteristic values ofthe pcsitioning
loads should be determined considering tbe largest
positioning velocities;md accelerations. Possible impact
loads sbould be included.
I
r' )
.
2.1.3.3 The velocities and accelerations during
positioning and seHlown of the object may be
determined by model tes(s and or Ibeoretical
calculations.
2.1.4 Loads from soil
2.1.4.1 The loads from Ibe soil are the foundation
reactions on mud mats, slabs, skirts. etc. during thespil
penetration phase, see also 2.1.5.
2.1.4.2 Loads from Ihe soil may be friction forces or
contact pressure. The characteristic vallJe of loads from
tbe soil should be determined considering the following
parameters;
soil material and soil parameters,
seabed topography, and
penetration depth.
)
DEI' NORSKE VERITAS
January 1996
Page S of IS
Rules for Marine Operations
Pt.2 Ch.4 Offshore btslallation
3. LAUNCHING
3.1 INTRODUCTION
3.1.2.4 Sensitivity analyses should be carried out
according to Pt. 1 Ch,3 Sec. 3. 2.
3.1.1 Application
3.1.1.1 Sec.3 applies to longitudinal and sideways
launching of objects from single transportation barges.
Launching from multi barge systems will necessitate
special considerations and requirements in addition to
tbose given in this chapter.
3.1.1.2 Launching of objects witb nnsymmetrical
launch frames will require special considerations with
respect to possible yaw motions.
3.1.1.3 Sideways launching operations sbould be
considered in a similar manner as IpogitucJinal launching
operations. Special cOlli!iderations shall be given to the
behaviour of the launch barge during launch.
3.1.2 General considerations
3.1.2.1 The following parameters sbould be considered
in relation to operational feasibility nod structural
limitations of the launcbed object nod orthe barge;
barge size,
position of the structure on the barge,
barge draught,
barge trim,
)
3.2 LOADCASES AND ANALYSIS OF FORCES
3.2.1 General
3 .2.1.1 A launching operation represents a series of
different loadcases from the initiation of the launch to
tbe stage where tbe barge and object floats separately.
3.2.1.2 The entire launching sequence should he
cODSidered step-by-step and the most criticalloadcase for
each specific member of the launched object should be
identified.
3.2.1.3 The trajectory of tbe launcbed object sbould
normally be computed by a dynamic analysis, In
general. a three dimensional analysis w.iIl be preferred.
The analysis should include assessmept of the barge
motions.
All significant forces influencing the behaviour of the
barge and launched object shoul~ be considered.
Particular attention should be given to the behaviour of
the barge nod tbe resulting uplift forces from the rocker
ann onto the launched object. .
Model tests may be used for verification of the computed
values.
barge bending moment.
barge submergence,
position of ballast water in the barge,
limiting environmental conditions,
rocker arm arrangement and rotational
limitations,
allowable rocker arm reactioDs,
friction coefficient, and
water depth.
3.2.2 Loadenses and force distribution
3.2.2.1 The basic loadease as given in 3. 2.1 should be
analysed-quasi-statically distributing the self weight,
buoyancy forces, barge support forces. etc., to the
structural members of the launched object and barge.
3.1.2.2 It sbould be shown that the launcbed object will
behave in a stable manner during the launching
operation. Model tests truly be used for verification of
the object's behaviour during launch.
3.1.2.3 The launcb sbould be initiated in a controlled
manner by removing the anti self launch devices andlor
by pushing/pulling the launcbed object to overcome the
static friction forces.
3.2.2.2 Loading effects from wind, motions due to
waves and the launch operation itself should be
considered. The resUlting increase in hydrodynamic
forces may be accounted for by use of a dynamic
amplification faclor on the static forces.
3.2.2.3 Loads determined from 3.2. 2.1 and 3.2.2.2
should be applied to the launched object and to the
launcb barge.
'lUgs should nol be used to initiate the launch.
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.4 Offshore Installation
January 1996
Page 9 of 18
3.2.2.4 Members exposed to slamming during launch
such as ri sers, jacket legs, buoyancy tanks, etc., should
be checked for the largest relative velocity at the actual
member. The relative velocities should be determined
according to 3.2.1.3.
3.3 .2.3 The buoyancy tank attachments to (he launched
object should be designed to withstand the hydrodynamic
and buoyancy loads acting aD the buoyancy tanks during
launch. A consequence factor of 1.35 shall be applied to
the primary steel attachments.
Guidance Note
3.2.2.5 Buoyant compartments exposed to hydrostatic
pressure loads should be checked for the largest
submerg~ draft. Accidental flooding of anyone
buoyant compartment should be considered when
determining the submerged draft.
3.3 LAUNCHED OBJECT
)
3.3 .1 General
3.3.1.1 Launched object refers to the main object and
aU attached items and apEurtenances e.g. buoyancy
tanks, control capsules. risers, j-tubes.
3.3.1.2 The spare buoyancy of the launched object
should be such tbat it satisfies the requirements for
launch trajectory, single damaged compartment, post
launch eqUilibrium and contingencies on estimated
weight and buoyancy.
3.3.1.3 The seabed clearance to the lowest protruding
member of the launched object during launch should not
be less than 5 meters or 10 % of the launch trajectory.
which ever is greatest.
.
3.3.1.4 Upon completion of the launching operation.
)
the object should remain afloat in stable equilibrium with
sufficient freeboard to allow for commencement of the
upending operation.
Guidance Note
The minimum freeboard may be taken as the,s!gnlficant wave height
ror installation plus 0.5 meters, however minImum rreeboard should
not be less than 2 meters.
The consequence ractor may be reduced considering the buoyancy
lank attachment system and consequence or an attachment failure.
3.3.2.4 Rubber diaphragms should have -,ufficient
strength to withstand internal and external water head or
air pressure including loads due to temperature cbanges
after assembly. A test programme including short term
and long term tests should be carried out to ensure
adequate strength. After the rubber diaphragms have
been mounted on the object special attention shall be
given to protect the rubber from the surrounding
environment, see also 3.5.5.4.
3.3.2.5 Anti self·launch devices should have sufficient
structural strength to withstand the horizontal gravity
component due to barge trim (heel). Friction may be
considered provided the lowest expected dynamic
coefficient of friction is used together with conservative
values for both static and dynamic barge trim (heel).
3.3.2.6 Launch lugs and similar structures ,hould have
sufficient structural strength to overcome the maximum
static friction forces, A skew load factor of 1.5 should
be applied. The pretrim may be taken into account.
3.4 LAUNCH BARGE
3.4.1 General
3.4.1.1 Barge equipment and systems should meet the
requirements of 3.5 with respect to capacity,
arrangement, inspection, and testing .
3.4.2 Stahility afloat
3.3.2 Structural strength
3.3.2.1 The launched object should have sufficient
strength to withstand the loads acting on the object as
described in 3.2.2. Special attention ,hould be paid to
local support loads acting on the launch frames ;Deluding
consideration of the properties and fabrication tolerances
of the launch timber.
3.4.2.1 The barge should have sufficient positive intact
stability and the necessary reserve buoyancy at all stages
of the launching operation. Relevant contingencies
should be included in the stability calculations, see also
3.1.2.2.
3.4.3 Structuralslrenglh
3.3.2.2 AuJtiliary and permanent buoyancy tanks and
other buoyant structures should be designed to withstand
the loads given in 3.2.2.4 and 3.2.2.5.
3.4.3.1 General requirements to offshore installation
operations are given in Pt. 1 CIz .2
3.4.3.2 Loads on the barge should be assessed in
accordance with 3.2.
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.4 Offshore Installation
January 1996
Page 10 of 18
3.4.3.3 The loads on Ibe launcb barge sbould be
verified to be within the barge's operutionallimitations
assessed by the barge's own Classification Society. Thjs
verification normally includes evaluation of;
bending and torsion of tbe barge bull.
rocker arm. reactions,
barge submersion,
barge hydrostalic stability, nod
special requirements from the Classification
Society.
Reinforcement should be subject to acceptance by the
barge'~
own Classification Society.
3.4.3.4 Any structural components on tbe barge not
assessed by the barge'S own Classification Society
)
should be verified to have sufficient structural strength
to withstand all loads during the launching operation.
Such structural components may include skidbeams,
positioning brackets for aUachment of positioning lines,
attachments for winches, hydraulic jacks, sheaves, etc.
3.5 SYSTEMS AND EQUIPMENT
3.5.1 Ballasting system
3.5.1.1 The barge ballasling system should have
sufficient capacity ~o achieve the predetermined barge
launch parameters within a time period Dot to exceed
25% of the wealher forecasting period.
)
3.5.1.2 The barge tank volume should have sufficient
spare capacity sueh Ihat the required trim. heel nod draft
can be maintained in tbe event of accidental flooding of
anyone compartment.
3.5.1.3 Halch covers over barge tanks should nol be
open prior to or during launch.
Guidance Note
Th!s may preclude the use of submersible pumps during the
ballasting operation.
.
3.5.2 Power supply and name cutting facilities
3.5.2.1 The power supply on the barge should have
sufficienl capacity for lighling during night work,
welding operations, etc.
3.5.2.2 The flame cutting facililies sbould have
sufficient capacity for cutting of the seafastening
members within a time period not to exceed 25 % of the
weather forecasting period.
3.5.3 Launch devices and systems
3.5.3.1 The objecllo be launched should be secured 10
the barge with anti self-launch devices to prevent a
premature launch after culling of the seafnstening
members.
3.5.3.2 Launeh lugs,. if applicable, should be designed
to provide self release of pulling wires after the
launching has started.
3.5.3.3 The launch inilialing push/pull syslem should
have sufficient capacity to overcome the static friction
forces, and should be capable of applying lhis force over
a sufficient distance to ensure initiation of the launch.
3.5.3.4 The sliding surfaces on the launch frames and
on the launch barge skid beams should have a finish and
capacity tbat assures a relatively low coefficient of
friction. For design nod planning of the launch
operation, the assumed. coefficient of friction should be
as specified by the manufacturer or as experienced in
similar operations (e.g., during load o~t). If more
accurate in-service values are not available. the
coefficient of friction between teflon and wood may be
taken as 0.OS.{).25 (static, break out included) nod 0.03O.OS (dynamic). The Teflon should be mounled on Ihe
barge skid beams. Similar values for lubricated steel and
wood may be taken as 0.1 - 0.2 (static, break out
included) nod 0.02 - 0.12 (dynamic).
3.5.4 Equipment arrangement
3.5:4.1 The equipment on Iheb.rge to be used prior 10
nod during lauoch should· be fit for its intended purpose
and arranged to ensure short start-up time.
3.5.4.2 The equipment on Ihe barge should be arranged
10 avoid damage to the object during launch.
3.5.4.3 The guiderails on the rocker arms should allow
for possible object yaw during launching.
3.5.5 Inspection and tests
3.5.5.1 All auxiliary equipment and systems to be used
during the launch operation should be uispected andlor
tcsted prior to departure from shore. The
lests/inspections should verify Ihal Ihe equipment nod
systems are in good working order and fit for the
intended use.
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.4 Offshore Installation
January 1996
Page 11 of 18
All structures and equipment necessary for the
operation nre correctly rigged, ready to be
used, aod bave been inspected aod tested
3.5.5.2 Preferably all buoyaot tanks e.g. buoyaot legs,
buoyancy tanks, should have n small internal
overpressure at departure from the shore. A monitoring
system should be arranged such that the pressure in the
tanks may be inspected at an easily accessible location.
Such an inspection should be performed prior to launch
to verilY tbe integrity of tbe tanks.
If there has been any leakage during the tow I adequate
measures should be performed to identify the extent of
the leakage an4 the cOIlBequences should be evaluated
prior to launching.
3.5.5.3 The barge, including tbe permaoent barge
systems and equipment, should be inspecled and/or
tested prior to departure from shore. The
tests/inspections should verify tbat the state of the barge
including the permanent systems and equipment is in
accordance with the requirements from tbe Classification
Society and are fit for the intended use.
3.5.5.4 Rubber diaphragms sbould be sbort tenn and
long tenn tested.
Eacb individual diaphragm sbould be tested to 1.25
times the maximum working pressure with a minimum
duration of 10 minutes.
One diapbragm of each type should be tested at 1.1 times
the maximum working pressure with .8 minimum
duration of 48 hours.
Obstacles whicb may unduly delay the
operation have been removed
3.6.1.2 Seafastening members sbould be cut in
accordance with a predetermined procedW'e containing a
number of steps. The cut lines should be. painted.
Continuous watch on the weather conditions should be
. performed, including the weather forec~t. The point of
no return should be identified in the procedure.
3.6.1.3 Seafastening members that bave been cut sbould
be removed and secured to the barge to avoid
interference with the object during launch.
3.6.1.4 Rigging equipment should be connected to
attachment points (padeyes, trunnions, bollards, etc.)
specially designed for tbe corresponding loads. Otber
attachment points should not be used.
3.6.2 Positioning of barge and object
3.6.2.1 The launcb barge sbould be positioned by lines
attached to the tugs. The object to be launched should
be connected '-'> positioning and hold-back vessels, by
lines with sufficient slack to allow free movement during
the launch.
The tests should be performed as close to sailaway as
possible.
)
3.5.5.5 A survey of tbe skidbeams and rocker arms
shall be perfonned to verilY tbat the alignment and level
is within the criteria coilside~ed in the structural
verification of the barge and the lallDched object.
3.6.2.2 The barge sbould be positioned relative to • set
of predetermined co-ordinates to ensure that the launched
object will not hit the seabed or structures positioned on
tbe seabed.
3.6.2.3 The barge beading for launch should, wbere
possible, be into the prevailing wind and wave direction.
3.6 OPERATIONAL ASPECTS
3.6.3 Monitoring of launching operations
3.6.1 Preparations for launching
3.6.3.1 The following parameters sbould be monitored
manually or by monitoring systems during preparations
for launch;
3.6.1.1 The following conditions sbould be complied
with before starting the cutting of seafastening and/or
ballasting of the launcb barge:
The environmental conditions, including the
forecasts, sbould be sucb that the complete
installatjon operation can be cOlDpieted in a
barge trim and draught,
barge position and orieDtntio~,
barge motions,
environmental conditions,
barge ballast aod stability parameters, aod
draught. heel, and trim of the object after launch.
well controlled manner and in accordance with
the design assumptions and the operations
manual
The launch position and orientation bas been
found acceptable
)
DET NORSKE VERITAS
n
January 1996
Rules for Marine Operations
Pt.2 Ch.4 Offshore Installation
Page Uof18
4. UPENDING
4.1 INTRODUCTION
4.1.1 Application
4.1.1.1 . SecA applies to upending operations of objects
carried out by controlled ballasting, flooding and/or
debaUnsting of buoyant compartments.
)
4.1.1.2 Upeoding operations assisted by crane lifting
operations are covered by Pt. 2 Ch.5, regarding tbe crane
lifting aspects.
4.1.2 General considerations
4.1.2.1 The following parameters should be considered
in relation to operational feasibility and structural
limitations of the object:
Hydrostatic stability
Ballasting/deballasting system's capacity and
redundancy
Limiting environmental conditions
Water depth
4.2 LOADCASES AND ANALYSIS OF FORCES
4.2.~
)
General
4.2.1.1 An upending operation represents a sequence of
different loadcases from the initial self-floating
condition to the fmal self-floating (installation)
condition.
4.2.1.2 10 principle the entire upending sequence
should be considered step·by-step and the most critical
loadcase for each specific member of the object should
be identified.
4.2.2 Loadcases and force distribution
4.2.2.1 The basic loadcases described in 4.2. ] should
be analysed by static analysis consideriog the buoyancy,
self weight and any applied loads. The structural
analysis verifying tbe global integrity of the object may
be omitted provided tbnt a similar structural analysis will
be carried out for the object for a more severe loading
condition during transportation. installation, or the ioplace phase.
4.2.2.2 Loads on buoyant compartments and buoyancy
tanks should be calculated for the largest submergence
draft. Accidental flooding of anyone buoyant
compartment should be considered when determining the
submergence draft.
4.3 STRUCTURES
4.3.1 General
4.3.1.1 Structures refer to tbe object to be upended and
any attached components e.g. buoyancy tanks, risers,
positioning brackets, clamping devices, rubber
diaphragms.
4.3.1.2 Upon completion of the upending operatioo,
the object should remain afloat in staple equilibrium and
with sufficient freeboard to allow commencement of the
positioning and setting operation.
4.3.1.3 The spare buoyancy of the object should
normally not be less than 10 % of the total buoyancy at
any stage, if not assisted by come. For crane assisted
upending operations the spare buoyancy should be
determined in each case,
4.3.1.4 The clearance between mudline and the lowest
protruding member should normally not be less th;m 5
meters for the critical position during the upenc.Hng
operation considering the lowest astronomi~ tide and
any motions imposed by the environmental conditions.
For the requirement given in 4.3.2.2 a clearance of
minimum 2 meters should be available.
4.3.2 Stability aIloat
4.3.2.1 It should be sbown that the object will behave
in a stable manner during the upending operation. The
initial metacentric height (GM), corrected for free
surface effec~t should normally Dot be less tban I meter
for any step during the operation. Model tests may be
used to verify the object's behaviour during upending.
4.3.2.2 Accidental flooding of anyone buoyant
compartment should be considered during evaluation of
hydrostatic stability and reserve buoyancy.
)
DEl' NORSKE VERITAS
I
~
January 1996
Page 13 of1S
Rules for Marine Operations
Pt.2 Ch.4 Offshore Installation
4.3.3 Structural strength
4.3.3.1 Structures should have sufficient strength to
witbstand tbe loads described in 4.2.
4.3.3.2 The buoyancy tank attachments sbould bave
sufficient structural strength to withstand buoyancy loads
and loads due to the transfer of ballast water.
4.3.3.3 FOT rubber diaphragJrul the requirements of
3.3.·2.4 apply.
4.3.3.4 Brackets
OD
the object used for positioning
purposes only should be designed to resist towline pull
from any likely direction. For desigo loads refer Pt.}
Ch.3.
)
4.3.3.5 Clamping lines and similar devices may be used
to secure articulated structures in a certain orientation
during upending operations. Clamping devices should
have sufficient strength to withstand loads due to
environmentnlloads, buoyancy, gravity. transfer of
baUast water. etc.
4.5 OPERATIONAL ASPECTS
4.5.1 General
4.5.1.1 The requirements of 3.6.1.1 apiJly.
4.5.1.2 The object to be upended sbould be positioned
nnd maintained at a predetennined location during the
upending operation by means of positioning lines. The
positioning lines should be attached and operated
without influencing tbe hydrostatic stability, clearance to
mud line, etc.
4.5.2 Monitoring of upending operations
4.5.2.1" Where applicable, the following parameters
should be mpnitored manually or by moni~oring systems;
dmugbt, trim and heel,
seabed clearance,
4.4 SYSTEMS
4.4.1 Ballasting and deballasting systems
4.4.1.1 The ballasting and deballastiog systems should
be designed, manufactured. installed, and commissioned
according to Pt.} Ch.2 Sec.5.
)
4.4.1.5 The Ballast compartments should, where
possible, be desigoed such that closing of tbe ballast
valve is Dot critical, Le. tbe compartments should be
flooded 100% once tbey are being utilised.
4.4.1.2 The ballast system, if applicable/including tbe
buoyancy tanks connected to the ballast system sbould be
designed such that the upending operation mny be
reversed at any stage.
environmental conditions,
amount ofwarer in the ballasting compartments,
open/close 'mode for valves,
air pressure,
ballasting rate, and
crane hook load .
4.5.2.2 The position and orientation of the object
should be monitored by surface andior underwater
positioning systems.
Guidance Note
Where it Is not practical to have a reversible upending ballast
system, the upendinglinstaliation procedure should clearly Identiry
points or no return. The ballast systems shall be designed so the
structure remain In stable equilibrium in cas!.'! of failure.
4.4.1.3 For articulated structures ballasting/deballasting
systems including the buoyant compartments should
have sufficient capacity to avoid overloading the
universal joint and to avoid exceeding rotational
limitations for the universal joint for normal and for
reversed upending operations.
4.4.1.4 1\vo separate methods sbould be available for
the starting or stopping of flooding of anyone
independent compartment. Whe re requirement in section
4.4.1.5 is satisfied a back-up metbod of halting flooding
may be omitted.
)
DEI' NORSKE VERITAS
Rules for Marine Operations
January 1996
Page 14 of IS
Pt.2 Ch.4 Offshore lnstallation
5. POSmONlNG AND SETI1NG
5.1 INTRODUCTION
5.2.2.2 Positioning line loads should be assessed
considering the maximum environmental conditions.
5.1.1 Application
5.2.2.3 Loads on buoyant compartmeDts and buoyancy
tanks should be calculated for the maximum
5.1.1.1 See.5 applies to positioning and setting
operations of objects where the vertical motion of the
object is achieved by controlled ballasting, flooding or
deballasting of buoyant compartments.
5.1.1.2 Positioning and setting operations assisted by
)
crane lifting operations are covered by Pr.2 ClI.5. as
regards craoe lifting aspects.
submergence draft.
5.2.2.4 Local loads on mudmats, slabs, skirts, dowel.,
bumpers, and guiding structures. etc. , sbould be
cOIlliidered during the setting I levelling, and soil
penetration phase.
5.1.2 General considerations
5.3 STRUCTURES
5.1.2.1 The following parameters should be considered
5.3.1 (;eneraJ
in relation to the operational feasibility and structural
limitations of the object;
hydrostatic -stability t
ballastina system capacity,
limiting environmental conditions,
positioning tolerances,
soil characteristics, and
on-bottom stability.
5.3.1.1 S~ructures ref~rs to the object to be positioned
and set and any attached components e. g. buoyancy
tanks, positioning brackets for positioning lines,
bump~rs, guiding structures (attached to the object or the
seabed), .clamping lines, mudmats, skirts, dowels.
5.3.2 Stability anoat
5.3.2.1 It should be verified that the object will behave
5.2 LOADCASES AND ANALYSIS OF FORCES
in a stable manner during the positioning and setting
ope.ratio~.
)
The initial metacentric height (GM) corrected
for free surface effect should nOnIUllly be at least f meter
during the op~rations.
5.2.1 General
S.2.1.1 The positioning and .setting operations represent
a sequence of different loadcases during the horizontal
and vertical translation of the object.
5.2.1.2 In principle, the entire positioning and setting
sequence should be considered step-by-step and the
most criticalloadcase for each specific member of the
object should be identified.
5.3.3 On-bottom stability
5.3.3.1 The object should have sufficient on-bottom
stability against pverturning and sliding due to
environmental loads before pennanent support to the
seabed is obtained.
5.3.3.2 The Do-bottom stability should ensure DO uplift
of the periphery of the object in the UL5 conditioo.
5.2.2 Load cases and force distribution
5.2.2.1 The basic loadcases described in 5.2 should be
analysed by a static analysis coIlliidering the bu.o yancy,
self weight, soil reaction, positioning loads, etc. The
structural analysis verifYing the global integrity of the
object may be omitted provided a similar structural
analysis is carried out for the object for a more severe
loading condition during transportation, installation or
the in-place phase.
Guidance Note
Any planed phase, e.g. planned hold conditions, without permanent
support to the seabed shall be desIgned and verified as a ULS case.
An situation where the structure must be left. without permanent
supports due to unplanned or unroreseen events shall be designed
and verified as a PLS case.
5.3.3.3 Limited uplift of the periphery of the object
may be accepted for the PLS condition, provided no
overturning or sliding will occur.
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.4 Offshore Installation
January 1996
Page 15 of 18
5.3.4 Structural strength
5.4 SYSTEMS
5.3.4.1 The object should have sufficient structural
strength to withstand the loads described in 5.2.
5.4.1 Ballasting and deballasling system
5.3.4.2 Buoyant compartments should have sufficient
5.4.1.1 The requirements given in 4.4.1 should apply
for the positioning and setting operation.
structural strength to withstand the loads described in
5.2.2.3.
5.3.4.3 Auxiliary buoyancy t."U1ks including their
attachments to the object should be designed to
withstand vibration loads due to pile driving jf the
buoyancy tanks are to remain in-place during pile
5.4.1.2 The ballastingldebaUasting systems on gravity
structures should be capable of levelling the object by
eccentric ballasting in order 10 counter uneven
settlement. The soil parameters and the seabed
bathymetry. see 1.3.1, should be considered for the
evaluation of ahove condition.
driving.
5.3.4.4 For positioning brackets the requirements of
4.3.3.4 apply.
5.3.4.5 Guides and bumpers attached to the object or to
the seabed, should have sufficient strength and ductility
to resist impact and guiding loads during positioning
without causing operational (e.g. position tolerance)
5.4.2 Mooring and towing system
5.4.2.1 The mooring and towing system to be used
during positioning and setting (installation) of the object
should be according to Pl. 1 Ch.2 Sec.5.3 and Pl. 2 Ch.2
Sec. 3.
problems and without overloading members of the
object. After positioning the guides and bumpers should
be able to resist londs due to object motions caused by
tbe sea. state, see PI.] Clr.2 Sec.5.4.
5.5 DOCKING
5.5.1 Gerteral
5.3.4.6 Anchoring and mooring systems should have
sufficient strength to withstand loads due to positioning
occurring during horizontal translation of the object and
relevant environmental loads due to wind, waves, and
current.
5.3.4.7 Clamping lines and similar devices attached to
articulated structures should withstand the loads
occuning during the positioning and setting operation.
)
5.3.4.8 Footing structures such as mudmals, slabs.
skirt, etc. should have sufficient ·strength to withstand
installation loads occurring during setting. leveUing and
soil penetration, see 5.2.
5.3.4.9 Footing structures should withstand forces due
to environmental loads before permanent attachment to
the seabed is obtained. Unacceptable settlement of the
object before permanent attachment to the seabed is
obtained should be avoided by sizing the footing
structures to ensure an acceptable soil pressure.
5.5.1.1 Docking operations may be perfonned
according to one of the foUowing principles;
vertical docl4ng, and
horizontal docking.
Docking is commonly us~ for accurate positioning of
platform substructures over a pre-installed template with
pre-drilled wells, but may also be used in other cases
when there is a need for accurate positioning of a
platform. substructure.
5.5.1.2 The docking piles against wruch the structure to
be positio)'led is docked should be in an accurate position
relative to the target poi.Qt.
5.5.1.3 A Positive clearances should be eosured during
the docking opemtion hetween the structure and the
template and wellheads. All movements, tolerances and
deformations shall be considered in the least favourable
direction.
5.5.1.4 Adequate positioning and monitoring systems
should be used during the operation. Normally, suitable
hydroaccoustic systems Oong-ninge and short-range)
transducers and responders sbould he used togetber with
underwater video cameras.
DET NORSKE VERIT AS
January 1996
Rules for Marine Operations
Page 16 or 18
Pt.2 Ch.4 Offshore Installation
5.5.1.5 Relevant accidental conditions should be
considered when selecting the docking system i.e.;
the docking system shou ld be able to resist a
relevant accidental impact load considering the
design environmental condition, mass of
structure and added mass from water. and tbe
method to be used,
a failure of ooe arbitrary positioning line, and
accidental flooding of anyone buoyant
compartment of the structure.
5.6.1.3 Clamping lines sbould be easy to release after
Completion of the installation operation. Nonnally.
clamping lines should .be released from a position above
the water surface.
5.6.1.4 The auxiliary buoyancy tank attachments to the
object should be desigoed to ensure quick and easy
release with regard to the removal of the tanks. The
tanks should DonnaJly be removed as soon as p'ossible
5.5.2 Vertical docking
5.5.2.1 Vertical docking is the method where it is
)
5.6.1.2 A fInal survey of tbe seabed including a final
testing of the undc[VJuter position/orientation monitoring
systems should be canied out prior to commencement of
the positioning and setting operation. see also 1.3.1.6.
easiest to ensure sufficient clearances throughout the
after jacket set down to reduce wave loading and
increase the on bottom stability.
operation. Two method are normally adopted, namely a
passive or an active system.
5.5.2.2 The passive system do not require outside
intervention e.g. people on the jacket, hydraulics. The
system should be desigoed with a primary and a
secondary docking pile, i.e. engaging one docking pile
at the time.
5.5.2.3 The active system normally lower the docking
sleeves down from the o~ject over the docking piles in a
predetermined sequence. Some rotation and translation
of the object should be possible after having lowered
down the docking sleeves. Lowering or the docking
sleeves should be performed by a suitable system e.g. by
a winch system.
5.6.1.5 The guiding structures should be desigoed to
ensure accurate positioning within the given tolerances
ror the project.
5.6.2 Monitoring
5.6.2.1 The position and orientation of the object
should be monitored by surface and/or underwater
positioning systems.
5.6.2.2 Monitoring of clearances to guiding structures
positioned on the sea~ed to achieve strict positioning
tolerances should be considered.
5.5.3 Horizontal docking
)
5.5.3.1 A bumper system is nonnnlly desigoed on the
structure to act against the docking piles during
horizontal docking.
5.5.3.2 particular attention should be paid to the
accidental load conditions as given in 5.5.1.5 and their
corresponding cODSequences.
5.6 OPERATIONAL ASPECTS
5.6.1 Genel1l1
5.6.1.1 The requirements given in 3.6.1.1, should
apply for positioning and setting operations.
DET NORSKE VERITAS
January 1996
Page 17 of 18
Rules for Marine Operations
Pt.2 Ch.4 Offshore Installation
6. PILING AND GROUTING
6.2.1.4 The piles and piling equipment should be
lowered and retrieved, where applicable, well away from
the structure and any other seabed structure e.g.
pipeline.
6.1 INTRODUCTION
6.1.1 Application
6.1.1.1 Sec. 6 applies to the execution of piling and pile
grouting operations for piled offshore structures such as
c .g. jackets. It is also applicable for underbase grouting
of jackets with plated foundations and gravity base
structures. see also 1.1.1.5.
n
6. 1.2 General considerations
6.1.2.1 The following should be considered in relation
to operational feasibility and structurallimitatioDSj
soil formation cbaracteristic,s,
hammer sizes,
back~up equipment,
pile driving procedure,
length of pile(s) above upper pile sleeve(s),
6.2.1.6 Special attention shall be given to pile and pile
guide design when the pile and/or hammer protrudes
through or are close to the splash zone. The natural
frequencies of the pile (free-standing) and pile/hammer
.system should be established. The pile and pile guide
should be verified for an applicable sea slate including a
range of wave periods, see also Pt. 1 Ch.3.
6.2.1.7 Systems and equipment to be used during pile
installation should comply with Pt.] Ch.2.
inclination of piles,
pile natural frequency (applicable for piles
or hammer which protrudes through or are close
the splash zone),
lifting equip'ment for hammers and piles,
lifting/upending procedure for piles, and
operational and accidental impact loads from
dropped objects or vessels.
~)
6.2.1.5 A proper arrangement for locating and guiding
the piles into the pilesleeves should be provided. This is
particularly important if the upper pilesleeves are under
the water surface and the pile driving is performed by an
underwater hammer.
6.1.2.2 Grout lines and packer inflation lines, if
applicable, should be designed to resist accelerations
from pile driving.
6.2 OPERATIONAL ASPECTS
6.2.2 (;1eaI1U1ces
6.2.2.1 HorizontiLI clearance between pile, hammer or
follower and structure primary elements should normally
not be less than 1m during slabbing and retrieval.
6.2.2.2 Any positive horizontal clearance during
driving through and nea( the splash zones are acceptable
if all components from fabrication tolerances, cleaiances,
deflections and pile sway (including possible dynamic
amplification) are summerized.
6.2.2.3 Nominal horizontal clearances between hammer
and primary structure during driving should nonnnlly
not be less than 1m.
6.2.1 Pile installation
6.2.1.1 The pile, should be installed in a sequence
providing adequate slability to the structure in all phases
of the installation.
6.2.1.2 Particular attention should be paid to
operational procedures when large self penetration
amllor llrun away" during driving of piles may be
expected.
6.2.1.3 The pile lifting and upending sequence should
be carefully considered. Eccentric loading on lifting
should be accounted for in the design, see also Pt.2 Ch.5
for general aspects to be considered during lifting.
6.2.3 Followers
6.2.3.1 Use of followers should be considered in order
to ~c(~e horizontal clearances during driving.
6.2.3.2 Followers shall be subject for periodical
inspections by suiLnble NDE and a maintenance record
shall be kept.
DET NORSKE VERITAS
n
Rules for Marine Operations
Pt.2 Ch.4 Offshore Installation
January 1996
Page 18 of 18
6.2.4 Grouting
6.2.4.1 Por GBS underbase grouting attention should
be paid to selection of systems, equipment and vessels
to ensure sound and feasible operations. Particularly the
positioning systems and manoeuvrability of the vessels
should be investigated to reduce the possibility of impact
londs to the insLalled object from the vessels, see also
Pt.] Ch.3 Sec.3.B.
Appropriate fendering structures should be considered.
6.2.4.2 The limiting environmental criteria should be
established for the grouting operationS considering;
vessel station keeping capabilities, grout system design.
ROV operability, etc.
)
6.2.4.3 No piling should be performed after
commeocement of the pile grouting operation.
6.2.4.4 Prior to transferring aoy heavy items,· e.g.
topside module, onto the structure the required grout
strength (curing time) should be documented. The grout
should be tested to verify that required strength have
been achieved.
)
)
DET NORSKE VERITAS
)
RULES FOR
PLANNING AND EXECUTION OF
MARINE OPERATIONS
PART 2 : OPERATION SPECIFIC REQUIREMENTS
)
PART 2 CHAPTER 5
LIFTING
JANUARY 1996
SECTIONS
1.
2.
3.
4.
GENERAL ....... •. .•...... .. .. .... .. ........ . .... .. ... .. .... •... .•... ... ..... .. .... . .. . . .•.. . ..•.......... . ... .. . . .... .. ...... . ... .. • S
LOADS .. . .. ... ......... . . . . .. .. . . ... ... .. .. ........ . ... .... . .. .. . . .. . . .. ... .. .......... . .. ... .... . .. ... ... ... .. ... .. .. .. . ..... ... . . ... . 7
UFTING EQUIPMENT ... . . . .... ..... ... . .. . .. ... ...... ... . . . .. .. ... . . ..... .... . . .. .. .. .. .. . . .. .. ... . . .. . . ... . ... . .... . . ..... .. . 12
STRUCfURES ..... ..... ................ .... ....... ... .. . .. .. ......... ... ... ...... ... ..... ... .. ...... .... ... ..... ......... .... .. ... 16
S. LIFT OPERATION ............................. .. .... ......... .. ...... .. . . . .... ......... ... ... ..... ....... ... .............. .. . .... 1&
6. YARD UFTS ............... ...... ... .. ........... .... ......... ..... .. ........ ... . ... ... .. .. . .. ............ .. ...................... .20
o
)
DET NORSKE VERITAS
Veritasveien I, N-I322 Hevik, Norway Tel.: +4767579900, Fax.: +4767579911
o
CHANGES IN THE RULES
This is the first issue of the Rules for Planning and
Execution of Marine Operations, decided by the Board
ofDet Norske Veritas Classification NS as of December
1995. These Rules supersedes the June 1985, Standard
for Insurance Warranty Surveys in Marioe Operations.
These Rules come into force on 1st of January 1996.
This chapter is valid until superseded by a revised
chapter. Supplements to this chapter will not he issued
except for minor amendments and an updated list of
corrections presented in the introduction booklet.
Users are advised to check the systematic index in tbe
introduction book1et to ensure that that the chapter is
current.
)
)
Det Not'8k:t~ Veritaa
Computer 1)'peselting by Del Nonke Veritaa
Printed in Norway by the Det Non;ice Ventss January 1996
@
.! .96.600
January 1996
Page 3 of 22
Rules for Marine Operations
Pt.2 Ch.S Lifting
CONTENTS
1.
GENERAL ••.•.•..•.•.•••••.••.•.•••••••.•••••••.•... 5
1.1
INTRODUCTION ...................•.... •.•. ....•.. 5
1. 1.1 Application .................................... 5
1.2
DEFINmONS ....................................... 5
1.2.1 Terminology ................................... 5
1.2.2 Symbols ...................... .... .............. 5
1.3
3.2.4 Inspection ..................... , .............. , IS
3.2.5 Certification of shacliles .................... 15
4.
STRUCTURES ..................................... 16
4.1
DESIGN CONDmONS ........................... 16
4.1.1 General ........................................ 16
4.1.2 Load factors .................................. 16
4.1.3 Uft points ..................................... 16
4.1.4 Ufting equipment ............................ 16
4.1.5 Ufted object .................................. 16
4.1.6 Bumpers and guides ......................... I?
4.1.7 Lay down arrangements .......... .. ........ I?
4.1.8 Seafastening arid griUage .... ~ ....... ....... t'7
4.2
FABRICATION AND INSPECTION ........... 17
4.2.1 Materials and fabrication ................... I?
4.2.2 Inspection ..................................... I?
5.
LIFT OPERATION ............................... 18
5.1
CRANE AND CRANE VESSEL ..... .. ......... 18
5.1.1 General ........................................ 18
5. 1.2 Positioning ........ ... ......................... 18
MISCELLANEOUS .......... .. ....... .... .... ...... 6
1.3.1 Planning ........................................ 6
1.3.2 Weather foreeast. ............................. 6
J.3. 3 Documentation ..... ... .... . .............. . .... 6 ,
(
2.
LOADS ................................................ 7
2. 1
BASIC LOADS ...................................... 7
2.1.1 Weight and centre of gravity ................ 7
2.1.2 Weight of rigging .... :........................ 7
2.1.3 Special loads ................................... 7
2.2
DYNAMlC"LOADS .................... ............ . 7
2.2.1 Dynamic effects ............................ .. . 7
2.2.2 Dynamic amplification factor ............... 7
2.3
2.4
:)
SKEW LOADS ..... :................................. 8
2.3.1 General ......................................... 8
2.3.2 Sling tolerance effects ................... : .... 8
2.3.3 Skew loads for multi·hook lifts ............. 9
2.3.4 Double slings ........ .......................... 9
2.3.5 Additional tilt ................................ 10
LOADCASES AND ANALYSIS OF FORCESI0
2.4. 1 General ................... , .................... 10
2.4.2 Basic loadcase and force distribution ..... 10
2.4.3 Additional loadcases ................. ........ 11
3.
LIFTING EQUIPMENT ......................... 12
3.1
SLINGS AND GROMMEfS ..................... 12
3.1.1 Minimum breaking load (MBL) ........... 12
3.1.2 Nominal safety factor ....................... 12
3.1.3 Handling ....... ............ .... ............... 13
3.1.4 Manufacturing and tolerances ............. 13
3.1.5 Certification of slings ....................... 13
3 .1.6 Inspection ........................ ........ .... . 14
3.1.7 Revalidation of slings ....................... 14
3.2
SHACKLES .... .. ...................... ... .......... 14
3.2.1 Safe working load ................. .. ........ 14
3.2.2 Design considerations ....... ................. IS
3.2.3 Manufacturing and testing .................. 15
5.1.3 Crane vessel certificates .. ....... . .......... 18
5.1.4 Crane documentation ....... ... .............. 18
5.2
OPERATIONAL ASPEcTs .... ...... .. ... ....... 18
5.2.1 Clearances during operation ............... 18
5.2.2 Ufting .... ..................................... 19
5.2.3 Monitoring oflifting operations ....... :... 19
5.2.4 Cutting of seafastening .... ...... ........... 19
6.
YARD LIFTS ....................................... 20
6.1
GENERAL ......................... •. .•...• ...... .... 2O
6.1.1 Application .. .. .............. ...... ........... 20
6.2
LOADS ............................................... 20
6.2.1 Weight and CoG ............................. 20
6.2.2 Specialloads .................................. 20
6.2.3 Dynamic loads ............................... 20
6.2.4 Skew loads ......................... ... .. ...... 20
6.2.5 Additional loads ............................. 20
6.2.6 Loadcases ......... ; ........................... 20
6.3
liFTING EQUIPMENT .......................... 21
6.3.1 Slings and grommets ........................ 21
6.3.2 Sbacldes ............. ..... ..................... 21
DET NORSKE VERITAS
f)
January 1996
Page 4 of 22
Rules for Marine Operations
pt.2 Cb.S Lifting
6.4
S1RUCTURES .... ........ •... •.................... 21
6.4.1 Lift points .... •..• .••.. .. . ....... ... •.. •. ... .. 21
6.5
CRANES •.. ••••• •. •.•.• ••.•.. •.•••.••.• •• .••••.. ..• • 21
6.5.1 Documentation ... ... .• .•..... .... .. .... .... . 21
6.5.2 Allowable loads ... .. .... ....... •.... .•.. ... • 21
6.6
OPERATIONAL ASPEcrs ... .....• •..•. •...... 21
6.6.1 Cleannces ..• •. .• . •...•••• .. .. ... .. ... ... .. ... 21
Figure List
Figure 2.1 - Determination of SKI." .. ..... •. .. •........ .. • 9
Table List
Table 2.1 - Dynamic Amplification Factors .. ..... ...... .. 8
Table 3.1 - Shackle Proof Loading.......... . ............ 15
Table 4.1 - Design factors ..... •..... •... •••... .... •. ...... 16
)
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DET NORSKE VERITAS
(
n
January 1996
PageS of 22
Rules for Marine Operations
Pt.2 Ch.S Lifting
1. GENERAL
1.1 INTRODUCTION
Grommet: Endless sling,
1.1.1 Application
Lifting: The activities necessary tq lift or assist a
structure by crane(s).
1.1.1.1 Pt.2 Ch.5, Lifting give specific guidance and
recommendations for well controlled lifting operations,
onshore, inshore and offshore, of objects with weight
exceeding 50 tonnes.
Guidance Note
In this context "Well contro[Jed~ means lifts planned, prepared and
performed according to requirements in Pi.t Ch.2, i.e. specially
prepared and documented.
Guidance Note
The prime objective far this chapter is to give requirements and
guidance for lifting in air. For sub sea lifting, relevant parts of this
chapter may be used together with Pf.2 Ch.B.
1.1.1.2 General requirements and guidelines are given
in Pt. 1 of these Rules. This chapter is complementary
to Pt. 1.
1.1.1.3 Conditions for using these Rules are stated in
Pl.O Ch.l Sec.l.2.
)
Lifted object: A structure or P"!"ls thereof subjectOci to
lifting.
Lift points: The attachment points for slings on the
lifted object. Lift point are normally designed as
padeyes or padear/trunnions.
Padeye : Li ft point on a siructuo! consisting of a steel
main plate with a matched hole for the sbackle pin.
The bole may be reinforced by a plate (cbeek plate) on
each side.
Plate s"aclde : A shackle where the bow is replaced by
two steel platcs and an extra pin.
Rigging arrangement: The complete ~ystem, as
applicable, of slings, shackles and, spreader beams orframes.
1.2 DEFINITIONS
Shackle: A structural component composed by B bow
and a pin linking e.g. a sling/grommet to a padeye.
1.2.1 Tenninology
Skew load factor: A factor ,accQunting for the extra
1.2.1.1 Definitions of terms are included in Pt.O CIJ.1.
Terms considered to be of special importance for this
chapter are repeated below.
Bobbin: Sheaves applied to increase the bending
diameter of double slings around a pin.
Cable laid grommet: Steel or fibre ropes arranged into
a stranded construction, ~bled together, right or left
lay, and spliced such that there is no end.
o
Lifting equipment: Temporary installed equipment such
as slings, shackles, sheaves. spreader beams or frames,
necessary to perform the lift.
loading on slings caused by the effect of inaccurate
other uncertainties with respect to
sling lengths
force distribution in the rigging arrangement.
and
Sling: A strap used between Jiftpoint and crane hook
during lifting. The term sling is also useil for a steel
rope with an eye at each eod.
Spreader beamlframe : Part of the rigging which may
transfer compression loads. It may be applied to;
avoid horizontal loads to the lifted object,
reduce the effect of inaccurate sling lengths or
to ayoid clashes between slings and the lifted
object.
Cable laid sling: Steel or fibre ropes arranged into a
stranded construction, cabled together, right or left Jay,
with a spliced eye in !:2ch end.
Designjactor: Factors to be applied for design of
structural elements which includes relevant load factors,
consequence factors, and local dynamics.
Trunnion: Lifting point 00 a stru~ture consisting of a
tubular member with a stopping plate at the end. The
sling/grommet may be laid around the tubular member
such that a shackle is not needed.
Dynamic amplificationjactor: A factor accounting for
the giobal dynamic effects normally experienced during
lifting. The dynamic amplification factor is defined as
(Dynamic load + Static Load)/ Static Load.
)
Fibre slillg: Slings made of high performance man
made fibres.
DET NORSKE VERITAS
()
January 1996
Rules for Marine Operations
Pt.2 Ch.S Lifting
Page 6 002
1.2.2 Symbols
1.3 MISCELLANEOUS
'The list below define symbols used in this chapter;
1.3.1 Planning
A :
CoG ;
D;
DAF ;
DHL ;
DIU., ;
d;
E :
F....
F(SPL);
F(SPL), ;
)
DO.
MBL ;
P;
SKI.. ;
SKI.." :
SKL., ;
SKI.,;
SKl.y ;
SPL;
SSCV;
SWL;
W;
Wrig :
Wri&,i:
.
<Xc.o ;
:
"";
"t:
)
Nominal cross sectional area of sling.
Centre of gravity.
Bending diameter of slings.
Dynamic smplificstion factor.
Dynamic hook load.
Dynamic haole loed for book no. i.
Diameter of sling.
Young's modulus.
Maximum dynamic sling load.
Additional hook load due to SPL.
Additional hook load due to SPL for crane
Ez;
1.·;
"t" :
'Yde.ip :
1, :
1m:
"ir:
1. :
"fIr:
'Yw:
e:
1.3.1.1 Planning and preparations for lifting
operations should comply with requirements and
philosophies given in Pt. 1 Ch.2.
1.3.2 Weather forecast
1.3.2.1 . Arrangements for receiving weather forecasts
at regular intervals prior to and, if applicable, during
the operation should be provided, see also Pt. I Ch.2
Sec. 3.2.
i.
Minimum breaking loed.
Nominal dynamic sling loed.
Skew load factor.
Skew loed factor due to elongation of slings.
Global skew load factor, see 2.3.2..
Skew load factor due to tilt.
Skew loed factor due to yaw.
Special loads, see 2.1.3.
Semi-submersible Cnp1C vessel.
Safe working load.
Object weight.
Weight of riggingllifting equipment.
Weight of rigging/lifting arrangement no. i.
M8lIimum theoretical part of total load at
hook no. i with CoG in extreme position.
Average strain in the slings caused by P .
Sum of sling and padeye fabrication tolerance
divided by sling length.
Average strain in the slings diagonal 1.
Average strain in the slings diagonal 2.
Reduction factor due to bending.
Consequence factor.
1.3.2.2 10 oroer to start an operation the received
weather forecasts should be acceptable according to
criteria in Pt.! Ch.2 Sec.3.2.
1.3,3 Documentation
1.3.3.1 The lifting operation should be described by
drawings, calculations and procedures. A manual
covering the ,elevant aspects of the lifting 9peratioD
should be prepared, see also Pt.! Ch.2 Sec.2.2.
1.3.3.2 Before start of lifting operations weight
reports, certificates, test rcports~ release DOtes and
classification documents for equipment, cranes and
vessels involved should, as applicable, be presented.
Design factor for lift points, equipment and
supporting structures.
Load factor.
Material factor.
Resulting reduction factor due to splicing or
bending.
Reduction factor due to splicing.
Nominal safety factor for slings.
Wear faclor.
Average sling angle from a horizontal plane.
DBT NORSKE VERITAS
o
Rules for Marine Operations
Pt.2 Ch.S Lifting
January 1996
Page 7 of 22
2. LOADS
2.1 BASIC LOADS
2;2 DYNAMIC LOADS
2.1.1 Weight and centre of gravity
2.2.1 Dynamic effects
2.1.1.1 The object weight (W) as lifted should be the
characteristic weight defined in Pt.] CIz.3 Sec.3.5.
2.2.1.1 All lifts are exposed to dynamic effects due to
variation in hoisting speeds, crane and v~sel motions,
cargo barge movements, object movements etc.
2.1.1.2 Inaccuracies in CoG position should be
)
2.2.1.2 The effect of global dynamics will be
considered according to the principles in Pt. 1 CIz.3
Sec. 3.5.
significantly influenced by p~eters such as;
the environmental conditions,
rigging a,rrangement
type of crane vessel.
2.1.1.3 For combinations of object and rigging
geometry sensitive to CoG shifts. any possible CoG
position should be considered in the design. It is not
recommended to substitute a CoG envelope study by a
weight inaccur~cy fuctor. see also PI. 1 Ch.3 Sec. 3.5.3.
Guidance Note
Geometry changes due to CoG uncertainties may for unconventional
rigging arrangements Innuence the design loads. The effect of the
geometry changes shall In these cases also be considered.
Guidance Note
To simplify purchasing and design of lifting equlpment,lifting points
etc., a sling load Inaccuracy factor. based on the weight inaCC\.lracy
and CoG envelope study, are"often used. The assumptions for this
factor, e.g . .CoG within envelope and weight within assumed
contingencies, must be confirmed.
stiffness of crane-boom and lifting appliances,
type of cargo vessel.
weight of lifted object
lifting procedure and
whether the lift is in air or water.
The global dynamic loads should be accounted for taking
proper account of these parameters, as applicable, see
also 2.2.2.
2.2.1.3 For Ilfts in water special investigations should
be made in each case l4lking proper account of the
hydrostatic and hydrodynamic effects, see also PI. 2
CIr.6.
2.1.2 Weight of rigging
2.1.2.1 The weight of rigging (W"') is the total weight
17 )
of the rigging arrangement, i.e. equipment such as
shackles, slings, spreader ban; or frames, etc.
.
Z.1.2.2 For some cranes rusa weight of hook, blocks
and hoist lines should be considered part of W",.
2.2.2 Dyn!lJl1ic amplification faclnr
2.2.2.1 The·global dynamic load effects may be
accounted for by using a dynamic ~plification factor
GuIdance .Note
This Is most relevant for cranes with several crane rigging
configurations typically for onshore crawler cranes.
u
Guidance Note
For lifting in waters !!ddltlon.allocal dynamic effects may become
governing for deSign af lifting equipment elements. Such effect
coulct be local ~lIng dynamIcs due to motion of the object Initiated by
waves.
.
(OAF).
2.1.2.3 W.... should be included in the applied crane
load, but does not need to be considered for elements
below each part of the rigging.
2.1.3 Special Inads
2.1.3.1 When appropriate, allowances for special loads
(SPL) should be made. Special loads may be tugger line
load •• guide loads. wind loads. hydrodynamic and
hydrostatic loads, etc.
2.2.2.2 The OAF should for major off·shore lifts be
established based on a dynamic analysis considering the
effects in 2.2.1.
Guictance Note
The dynamiC loads may be categorised as environmental loads (E
loads), sse Pl.1 Ch.3 Sec.3.1. Appropriate load factors according to
Pt.1 ChA Table 3.1 may be considered when calculaUng the
dynamic hook load.
2.2.2.3 Environmental design conditions applied in the
dYDamic analysis should be duly reflected in the
operation manual, see also Pt. 1 Ch.2 Sec.3.1.
)
Orrr NORSKE VERITAS
n
January 1996
PageS 0(22
Rules for Marine Operations
Pt.2 Ch.S Lifting
2.2.2.4 In lieu of more refined analysis the values for
DAF given in Table 2.1 may be coosidered as minimum
factors for lifts in air, provided the lifting operation will
not take place under adverse conditions.
Guidance Note
For offshore lifting fram deck of SSCV's the OAF for inshore lifts In
Table 2.1 may normally be used.
2.3.2.2 The SKI.,. SllOUld always be calculated if the
slings or lift points have excessive fabrication tolerances,
the rigging has an unusually geometry, e.g. small sling
opening angles andlor no symmetry and if slings with
other stiffness properties than wire rope and cable laid
steel slings are used, see 2.3.2. 7.
Guidance Note
ForO> 6Odeg., see 2.3.2.7, and utUlsaUons less than 0.8 the skew
load effects due to sling length tolerances should be calculated In
each case.
2.3.2.3 For ,tatically determinate lifts with ,ling
1.30
)
1.05
1.10
1.20
1.05
1.05
1.15
1.05
1.05
1.10
lengths within the tolerances specified in 3.1.4.2 a SKl"
of 1.0 may be applied. If the slings are not matched,
i.e. not within the tolerance specified in 3.1.4.2, the
effect oftolemncts on rigging geometry and sling loed
distribution should be considered ..
2.3.2.4 For four points lifting with "floating" spreader
bars, and sling lengths within tolerances specified in
3.1.4.2, a SKI.,. of 1.1 is normally acceptable.
2.3 SKEW LOADS
2.3.2.5 For statically indeterminate 4 points lifts with
2.3.1 <ieIleral
2.3.1.1 Skew loeds are the extm loading caused by
equipment and fabrication tolerances, and other
uncertainties with respect to force distribution in the
2.3.2.6 As an alternative to above SKl" may be
rigging arrangement.
calculated in accordance with 2.3.2. 7.
2.3.1.2 Skew loeds and load effecls due to;
sling length inaccuracies,
2.3.2.7 Direct calculation of the SKl" may be based on
a sling load of 1.3 times that determined from the DHL.
The SKI.,. will decrease with increasing load ,ince the
relative difference between the sling loads will decrease.
This effect is illustrated in Figure 2.1. The loaddeflection curves of the slings may be approximated as
linear for the pU'lJOse of calculating the SKl".
fabrication tolerances of lift points,
multi hook lifting,
doubled slings and
sling elongation
)
total sling and pedeye tolemnces within the requirements
specified.in 3.1.4.2, a SKI.,. of 1.25 is normally
acceptable.
should be evaluated for each lift.
lifting procedure may cause other skew loed effects than
mentioned in 2.3.1.2.
It is recommended not to select too strict strength
tolerances when skew loaa calculations are performed.
SKl" below 1.1 should normally not be applied for a
statically indeterminate lift of a relatively rigid object.
2.3.1.4 The skew load effects should be considered as
In Eq. 2-1 the lifted object is assumed infinitely stiff,
and no rotation of the crane hook is considered. As a
2.3.1.3 It should be carefully evaluated if the pl:lDDed
outlined in the sub-sections below.
further refinement the object flexibility and possible
crane hook rotation may be taken into account.
2.3.2 Sling tolerante effects
2.3.2.1 The effecls of sling length tolemnces is
dependent on the fabrication tolemnct of slings and lift
points, the rigging geometry and the utilisation of the
slings. The effects may be accounted for by a factor
SKl".
)
DEI' NORSKE VERITAS
January 1996
Page 9 of 22
Rules for Marine Operations
Pt.2 Ch.5 Lifting
The below formula may be used for calculation of the
SKL" for a 4 point statically indeterminate lift with
approximately a double symmetric single sling
arrangement, and E ~ Eo.
SKL" = 1
+ £0/"
Eq.2-1
average strain in the slings at hook load 1.3 DHL
(no skew load assumed).
1.3 F,ID,.!A E sin(S).
F,,,,, : dynamic sling load in N.
A:
3.14d'/4
d :
diameter of sling in mm.
E:
Young's modulus for the sling, could for cable
laid slings be laken as 30.000 MPa based on A as
defined above.
S:
average sling angle from a horizontal plane.
Eo:
total sling and padeye fabrication tolerances (or
"=
possible length deviation) as a function of the
sling length. i.e. £0= total tolerancelsling length.
Guidance Note
For lifting with grommels, the sling area A should be taken as the
total ,sling cross sectional ""rea, I.e. sum of both parts.
f----,
increased sling loading due to rotation of the object
about a vertical axis. Normally a yaw effect factor of
1.05 is sufficient. For lifts with small sling opening
angles at the hooks and/or significant wind/tugger line
loads a greater yaw effect factor could be appropriate.
2.3:3.4 A tilt effect factor, SK4. should be calculated
to account for the increased sling loading caused by
rotation of the object about a horizontal axis, and the
effect of not plumb hoist lines. The tilt effect factor
should be based on possil>le tilt caused by maximum
hook height tolerances and hoist line deviations from
plumb.
Guid~nce
Note
2.3.3.5 For lifts involving more than two hooks, the
maximum variatipn in load di$tribution betwe{:n the
hooks need to be specially considered. see also 6.2.4.1.
•
1.0
SlingDiogomll
p
•
"
P
ioadinsling
f:
awrngo mrain in sling (eloogalioolsling length)
Co
E\
sling length fabiication tolaranoo
c:z
2.3.3.3 The yaw effect factor, SKly, account for
For lifting with crane vessels the tilt effect factor may normally be
caiculated for a tilt of 3° when the cranes are on the same vessel,
and for a tilt of 50 when the cranes are on separate vessels (holst
line deviation Included).
Fi ure 2.1 - Detennination of SKL
SKI.
2.0
depend on whether the two cranes are on the same or
separate vessels, the vessel's motion response, and the
lifting procedure.
where
E. :
2.3.3.2 The effect of any CoG position within the
defined envelope and Ule effect of tilt and yaw shall be
considered for multi hook lifts. The yaw and tilt effects
may result from deviations of the hooks from their ideal.
relative positions. The magnitude of this deviation will
2.3.4 Double slings
2.3.4.1 For doublad slings, e.g. both eyes connected to
same .l ifting point, unev~n loading of each part can occur
and should be considered in the design.
2.3.4.2 Equal loading of each part of the sling can be
assumed for single hook lifts that does not involve
upendingltilting (e.g. rotation of the slings over a fixed
tIllIllllon or similar after the slings are loaded, and each
part have the same axial stiffness.
2.3.4:3 For lifts that do involve upendingltilting or
different axial stiffness of each part, the effect of !J.Deven
avor.:lge strain in sling cfI::J.gooal1
a;oarage strain in sling diagma12
distribution between the siing parts should be considered
assuming a maximum possible sling friction coefficient
at the hook, trunnion, slIackIe etc. Friction coefficient
2.3.3 Skew loads for multi-hook lifts
values less than 0.10 for well coated slings should
normally not be used. For slings with a dry surface a.
2.3.3.1 Skew load effects caused by use of multi-hook
lifts shall. in addition to skew load effects for rigging at
each hook, be considered.
higher friction coefficient values should be considered.
)
DET NORSKE VERITAS
()
Rules for Marine Operations
Pt.2 Ch.5 Lifting
January 1996
Page 10 of 22
2.3.4.4 If Ihe doubled slings consisls of Iwo parallel
slings, the load distribution should be calculated
considering Ibe maximum sling lenglb difference and
maximum sling E modulus.
DHI., = DAF «cxc.o - SKI.,· W)
+ W....l! + F(SPL),
Eq.2-3
where
2.3.5 Additional tilt
2.3.5.1 Differenl sling elongation, sling lenglh
tolerances and lift point fabrication tolerances couId
in=e Ibe object tilt. If the lifting poinls are below the
object vertical CoG, the loading in the most utilised
slings will then increase. In this case a factor, SKI....:,
should be eslimated.
2.4 LOADCASES AND ANALYSIS OF FORCES
2.4.1 General
.2.4.1.1 A lift opemtion does not represent one well
defined loadcase, but a sequence of differenlloadcases.
Uncertainties with respect to internal force distribution,
ske,,! loads, dynamics, 'possible accidental loads, etc.,
will introduce further complications.
2.4.1.2 In principle the entire lifting sequence should
be considered step-by-step and ·the most critica1loadcase
for each specific melIlber should be identified. However,
for most conventional lifts, the entire sequence is
adequately covered by Ibe basic loadcases described in
2.4.2 and Ibe addilionalloadcases described in 2.4.3.
)
2.4.2.2 For Iwo hook lifts, Ihe dynamic hook load for
each hook (DH4) are normally expressed as :
2.4.1.3 For lifting opemtions including pivoling!
upending critical sleps have 10 be identified and
analysed.
Clc.o: Maximum Iheoretical part of lotalload at hook
"i" with CoG in extreme position.
SKI..,. :Pactor expressing the increase in hook load "i due to tilting of the object.
2.4.2.3 The basic loadcase ror a lift should nOrmally be
calculated as a quasi static loadcase by applying DHL at
the hook position, and distributing weight and any
special loads to each element.
2.4.2.4 In order 10 find maximum dynamic forces for
each element (e.g. sling, Lift points, supporting
structure), the sling forces found in the basic loadcase
according to 2.4.2.3 should be adjusted considering all
relevant skew load effecls as described in 2.3.
2.4.2.5 The skew load effeels will increase Ibe force in
some slings, und reduce the force in the others
accordingly. Hence, it may be necessary to define
various loadcases in order to cover all possible
combinatioD,5 of sling loads.
Guidance Note
For a conventional four sOng 11ft, the following two (skew) load cases
'should nonnally be considered:
1. The force distrtbutJon calculated according to 2.4.2.3 modified
by multiplying the fOfces in two diagonally opposite slings with
the skew load rador. The forces in the remaining two sl1ngs
should be detennined by (quasi) slatic equl1ibrlum.
2. Ditto but with the skew load applied on the other pair of slings.
Guidance Note
The f1exibnity 01 the object will reduce the SKl. This effect should
be considered for less torsion stiff objects such as h~ lIdecks etc.
Guidance Note
Critical step shall at least include dimensioning positions for all
elements connected to the lift points.
2.4.1.4 Special considerations will be necessary for
lifting operalions in water. Guidelines for such lifting
operations are given in Pt. 2 Ch. 6.
2.4.2 Basic loadcase and force distribution
2.4.2.1 For single hook lifts, the dynamic hook load is
normally expressed as :
DIlL = DAF(W + WnJ + F(SPL)
Eq.2-2
DIlL : Dynamic hook load.
DAF : DynainIc amplification factor I see O.
W : Object weight, see 2.1.1.1.
W... : rugging weight , see 2.1.2.
SPL: Special loads, see 2.1.3.
F(SPL) : Additional hook load due 10 SPL.
2.4.2.6 The maximum dynamic forces calculaled
according to 2.4.2.4 are the design forces for
slings/grommels and shackles. For the design of
structural components, the maximum dynamic force
should be muUiplied by ihe appropriale design faclor
givenin Table 4.1.
2.4.2.7 If lugger lines are allached 10 Ihe lifted objecl,
the attachment poinls should have adequate struclural
slrength to withstand Ibe maximum loads which can be
imposed by the lugger lines.
GuIdance Note
Preferably the tugger lines shOUld be equipped with a system, e.g. a
constant tension winch system, which restrict the maximum loads to
a specined value.
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.S Lifting
January 1996
Page 11 of22
2.4.3 Additionalloadcases
2.4.3.1 Members which may be exposed 10 loads not
adequately covered under 2.4.2 should be identified and
design loads established accordingly.
2.4.3.2 Loads due to rotation of object in slings when
lifted, see 2.3.4, shall be considered in loadcases for
lifting points and lifting equipment.
2.4.3.3 Load effects due to possible directional
deviations of the sling forces should be evaluated and if
o
Decessary considered in the design verification.
2.4.3.4 A lateral load for lift points and lifting
equipment, acting simultaneously with tbe in-plane load,
should be considered in the design, and not taken less
than 3 % of the maximum sling force. The lateral load
should be applied at the point of action, e.g. at the
shackle bow, at the trunnion stopper plate, ele.
r' )
o
DEr NORSKE VERITAS
n
January 1996
PageU of 22
Rules for Marine Operations
Pt.2 Ch.5 Lifting
3. LIFTING EQUIPMENT
3.1 SLINGS AND GROMMETS
3.1.2 Nominal safety factor
3.1.1. Minimum breaking load (MBL)
3.1.2.1 The nominal safety factor, y" for slings and
grommets sbould include tbe foUowing factors:
3.1.1.1 Slings or grommels may be constructed from
1, :
Load factor = 1.30 (For lifts with a well
controlled weight, and were all skew load effects
bave been tboroughly considered a y, = 1.20
may be used).
Y. :
Consequence factor
single steel rope, or be composed of several steel ropes,
eaCh spinned of strand.., whicb are spinned of steel
wires. Preferably tbe rope MBL sbould be determined
by pulling the wbole rope to destruction. If no facilities
are available for such testing. tbe rope MBL should be
)
(If single sling
established in accord..nce with a recognised standard.
failure does not cause a total loss, or the
3.1.1.2 For grommels the strength of the core part
consequences of sling failure may be regarded as
small, a lower factor may be applied)
sbould not be included when establishing the MBL.
'Y. :
Reduction factor due to splicing. This factor
could be taken as \.33 for cable laid slings
spliced 'as described .in PM 20, see 3.1.4.1. For
other types of slings/grommets and splicing (or
fCOllle seCured) this factor bas to be documented.
'Yb :
Reduction factor due to bending. For slings of
steel wire .ropes this factor should be taken as;
3.1.1.3 When fabricating slings from several unit
ropes, the sum of the various unit rope MBL's, should
be divided by a sling spinning loss factor of 1.18
(1/0.85), prior to establishing the total sling MBL.
3.1.1.4 Fibre slings may be acceptable. For lifting
with fibre slings due attention sbaH be made to the fibre
material stability over time when exposed to a marine
environment aDd UV radiation. Only fibre material with
stable material properties sball be used.
1b
Yb for fibre slings may be taken as \.0. The
bending diameter for fibre slings sball not be less
than minimum bending diameter specified by tbe
fabricator.
Yr :
Resulting reduction factor due to splicing or
bending. This factor sbould be taken equal to the
greatest of 1. and lb'
1w :
Wear factor = \.00 for single application
purposes. For mUltiple used slings, the Yw
sbould be subjected to individual evaluations by a
competent person. For slings in good conditions
Yw does Dot be take greater than 1.1.
1m :
Material factor for lifting slings. This factor
could be taken as 1.35 for certified new steel wire
rope slings, .see 3.1.5.1. For lifting with fibre
slings an ample material factor sball be applied
(norma1ly Ym" 3.0). For material with indigent
creep properties a higheqm sball be used.
SWL sbould be taken according to Eq. 3-1.
SWL
= MBL,,,,,, I Y.,
Eq.3-1
where
y.,:
see 3.1.2.2
= I/(Hl.5/(D/d)°-')
=
=
speeified by the fabricator. The minimum bending
diameter for the sling sball be specified.
3.1.1.7 Fibre slings sbaJJ be proof load tested. The
proof load sbould not be less than specified in Table 3.1.
o
Eq.3-2
temperature properties of the load bearing fibre material.
Load bearing material where the MBL of tbe sling
during operational conditions is affected by creep or
temperature, should not be used.
3.1.1.6 The MBL of the fibre slings sball be as
o
where:
D diameter of bend
d
nominal diameter of sling or single part cable
laid grommet.
3.1.1.5 Due attention sbaJJ be paid to tbe creep and
)
= 1.30
DET NORSKE VERITAS
(
Rules for Marine Operations
Pt.2 Ch.5 Lifting
January 1996
Page 13 of22
3.1.2.2 The loW nominal safety factor should be taken
as Ihe grealesl of:
"'I.r = YrYe"'lr Yw Y=
Y., = 3.0
Eq.3-3
3.1.2.3 Calculated maximum dynamic sling load F .....
should fulfil Eq. 3-4;
MBJ:."ing
Fsling
<
Y
Eq.3-4
3.1.3 Handling
o
3.1.3.1 The eye of a single part sleel sling should nol
be bent around a diameter less than the nominal diameter
of the cable laid rope from whicb il i, formed.
Guidance Note
In order to maintain the sling eye in good condition the sling eye
should not be bent around a diameter less than three times the sling
diameter.
3.1.3.2 10 order to maq,lain sleel slings and grommets
in good condition nO other parts should be bent around a
diam~ter less tban 4 times the nominal diameter of the
cable laid rope. A reduclion of Ibe capacity due 10
bending should nevertheless be considered, see 3.1.2.1.
3.1.3.3 Bending in way of spliccs shall be avoided.
3.1.3.4 Bending in way of grommet butt connections
sh,a11 be avoided. The location of the butt connections
sball be marked.
()
o
3.1.4.1 The manufacturing of slings and grommets
should be performed by a recognised manufacturer. The
rope conStruction should be well suited for the intended
use and comply with recognised codes or standards, e.g.
Veritas Rules for Certification of Lifting Appliances.
1994. or International Slaodacd ISO 2408. For beavy
cable laid ropes Guidance Note PM 20: 'Cable Laid
sUngs and Grommets' from Britisb Health and Safety
Executive. apply.
.f
o
)
3.1.4 Manufacturing and tolerances
3.1.3.5 Sling lay down layout should be carefully
considered to avoid possibility of twisting during rigging
and tensioning. The slings sbould be marked.
preferably with a longitudinal paint marking.
3.1.3.6 Due considerations to avoid connecting right
and left band laid ropes sball be made wben several
slings are connected together.
3.1.3.7 lflifting is arranged witb a single sling between
lifted object and crane hook possible rotations of either
hook (due to swivel arrangements in hook) or object
shall be restrained.
3.1.3.8 For lifting witb fibre slings. rigging design and
lift procedure shall thoroughly consider and prevent the
possibilities for mecbanical damages (e.g. cutting or
abrasion) and sliding of tbe sling relative to the lifted
object. The possibility for abrasion or damage due to
elongation of the sling during loading , hall be
considered.
3.1.4.2 The length of cable laid steel slings. grommets
or fibre slings should normally be within tolerances of
iO.25% of their nominal length.
The length of ordinary wire rope slings or grommets
should normally be within tolerances of iO. 15% of their
nominal length.
Guidance Note
During measuring, the slings or grommets should be funy supported
and adequately -tensioned. The tension load should be In the range
of 2.5 - 5.0 per cent of MBl. Matching slings should be measured
with the same tension load and under sImilar conditions.
Testing equlpme,nt not able to comply with the above tension load
reqUirement could be test according 10 the procedure given below:
For each sling it series of at least 3 - three - separate lensioning
tests should be carried out, up to the available tension load.
Measurement of elongation and force shall be taken at intervals.
Based upon this, a theoretical elongation can be estimated for a load
COITesponding to 2.5% of MBl. Bending diameter during the
tensjonin.9 lest should be specified. Depending of the results, a
skew load factor correclion may be required.
3.1.5 Certification of slings
3.1.5.1 For slings and grommets made of steel wire
ropes a Makers Certificate sbould be provided. For
slings or grommets used 'with a material factor of 1.5, a
"3. 1C" certificate issued by a recogni,ed Certifying
Body is normally required.
3.1.5.2 The sling certificate should contain tbe
following minimum information;
certificate Dumber,
date of certification.
sling/grommet identification code,
Dame of manufacturer,
date of manufacture,
sling/grommet diameter and lenglh and
type of construction,
3.1.5.3 Additionally for cable laid slings or grommets
certificate no.'s for unit rope (certificate to be
enclosed),
minimum breaking lond (MBL) of rope and
minimum breaking load (MBL) of sling or
grommet.
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.5 Lifting
January 1996
Page 14 of22
()
Guidance Note
Discard criteria and tesUng requirements should comply with the the
following Standards:
3.1.5.4 Additionally for fibre slings;
minimum bending diameter,
proof load
1503t08
1504309.
Det Norske Vcritas rules ror liRing appliances.
3.1.5.5 Each sling or grommet should be clearly
identified with reference to the corresponding certificate.
3.1.6 Inspection
3.1. 7.6 For revolidation of sling. with. MBL
exceeding lOOOkN tbe additional requirements in 3.1.7.7
through 3.1. 7.9 apply.
3.1.6.1 Afllifting equipment shall be in good condition
3.1.7.7 There should be a data/log book for each sling
and thoroughly inspeeted before each lift or series of
lifts.
containing as a minimum the following information;
3.1.6.2 Slings and grommets shall be inspected by a
competent person. Special attention should be given to
the condition of splices and tenninations.
all relevant certificates,
handling and conservation procedure,
survey reports, and
stomge time and conditions.
3.1.7.8 Preservation procedure, including specification
)
of protection medium, should be developed.
3.1.6.3 Slings with;
damage.,
apparent deterioration
uncertain internal condition ,
uncertain handling or storage history,
certificates older than 2 years, and
overload indicators showi,ng sign of previous
overloading (relevant for fibre . lings).
shall be subject for a revalidation according to 3.1.7
3.1.7 Revalidation of slings
3.1.1.1 Slings and grommets subject for revalidation
shall be thoroughly inspected and evaluated by a
competent person. Destructive testing and jssua,n~e of
new certificates shall, when required, be don~ by a
recogn,ised sling manufacture or body.
3.1.7.2 Sling. ,ubject for revolidation should be
)
properly cleaned. Random opening should be carried
out to check for internal condition and corrosion. The
number of openings is .ubject to the length of the sling,
but the sling should minimum be opened at least three
different places.
preservation requirements as non-galvanised slings.
3.1.7.10 For revalidation of cable laid . ling the
additional requirement. in 3.1.7.11 through 3. 1.7. 13
apply.
3.1.7.11 Cable laid slings and grommets subject for
revalidation shall be tboroughly inspected and evaluated
by a competent person from a recognised sling
manufacrure.
3.1.7.12 10 addition to requirements in 3.1.7. 71he
data/log book for each cable laid sling should contain;
reCords of previous liftS,
lift weights and,
bending radius.
3.1.7.13 When cable laid sling. are being handled, the
owner or an appointed representative should witness the
operations. Any incidents sball be recorded in the log
book for the sling. Speciol attention should be given to
incidents resultiong in compression loads in splices.
3.1.7.3 The rope, or unit ropes of one sling if cable
laid, of a series of used slings shouid be subjected to
destructive testing if there are uncertainties with respect
to capacity or internal conditions of the ropes.
3.2 SHACKLES
3.2.1 Safe working lnad
3.1.7.4 The nominal length of slings as specified in
3.2.1.1 The safe working load is generally used as
their originol certificate., should be verified by
measuring under tension prior to issuance of new
certificate.
3.1.7.5 Derating of sling capacity, instead of discarding
is normally not accepted .
0)
3.1.7.9 Galvanised slings shall be subjected to the same
reference. for the strength of shackles. SWL is normally
determined by the maker or a Certi fying Body. The
shackle minimum breaking load, normally defined by
specifying a minimum .afety factor on SWL, sholl be
documented.
)
DET NORSKE VERITAS
\1
Rules for Marine Operations
Pt.2 Cb.5 Lifting
January 1996
Page 15 of 22
3.2.1.2 The shackle allowable load shall Dot be taken
greater than the minimum of;
a)
SWL"DAF
b)
MBU3.3.
The acceptance criterion defined by Eq. 3-1 in Pc. 1 Ch.4
is fulfilled when the dynamic shackle load does not
exceed the allowable load as defined above.
3.2.2 Design considerations
o
3.2.2.1 Shackles ace designed and load rated to support
centre line loading of the shackle. Other load conditions
should normally be avoided.
Guidance Note
o
Eccentric loading may be acceptable If the shackle capacity Is
derated according to the manufacturer guidelines and/or
calculations.
3.2.2.2 Shackle dimensions should be selected with due
regard to bending radii of slings and grommets, see
3.1.3.1 and 3.1.3.2.
3.2.2.3 It is not recommended to connect shackles
together. However, sbncldes connected bow to bow is
normally aeceptable.
3.2.3 Manufacturing and testing
3.2.3.1 The manufacturing and testing of shackles to be
used for lifting should be carried out according to sound
practice and in accordanpe with a recognised code or
standard. For plate shackles 4.1.4 applies.
o
3.2.3.2 Material requirements for new shacldes sbould
be in accordance with the requirements as summarised in
table Dl in DNV - Rules for Certification of Lifting
Appliances.
Guidance Note
Old shackles that do not comply witJ:I the requirements given in
3.2.3.2 may be acceptable If produced ~y a recognised shackle
manufacturer. Whether an old shackle is acceptable or not should
be decided on the basis of the Information availabl; , anc;f the results
of the non destructive examination, see also 3.2.4 and 3.2.5.3.
3.2.4 Inspection
3.2.4.1 Each shackle sbould be inspected before each
lift in order to reveal any traces of ~xtrnordillary
loading, damages, cracks etc.
3.2.4.2 For shackles in good condition thnt comply
with the requirements in 3.2.5 and without traces of
extraordinary loading, damages J cracks etc. a visual
inspections will normally be sufficient.
Otherwise the ,backles shall be subject for thorough
visual inspection, magnetic particle inspectioD J and
ultrasonic testing before used_
3.2.5 Certification of shackles
3.2.5.1 A makers certificate and a proof loading
certificate signed by a recognised Certifying Body
should be provided for each shackle.
3.2.5.2 A shackle certificate sbould normally contain
the following minimum information;
certificate identification code J
shackle identification code,
name of manufacturer,
date of manufacture.
material type,
manufacturing method,
reference code, standard or specification,
minimum breaking load.
proofload.
safe working load and
date of certification.
3.2.5.3 For old shackles produced by a recognised
manufacturer, where the material can not be proven to
comply witb 3.2.3.2. the proof loading certificate should
not he older than 2 years.
3.2.5.4 Each sbackle should be clearly ideDtified with
reference to the corresponding certificate. The safe
working load as specified in the certificate should be
clearly marked on the shackle.
3.2.3.3 Eacb individual sbackle sbould be proof loaded
after fabrication The proof load should not be less than
indicated in Table 3.1.
Table 3.1- Shackle Proof Loadine
~~~~.;:.·-:.~'.: ;;3!" ~,::,~'~,~'i;> ~',j·:'·'~'I: ~s;t~#:~·~:·;.:;
Proof Load
2' SWL
1.22·SWL + 201
',. ,. /f~~,S~~~ :
1.aa'SWL
3.2.3.4 A sbackle should not be used if the inspection
after the proof loading reveals any geometrieal
deformations, cracks, or other defects.
DET NORSKE VERITAS
January 1996
Rules for Marine Operations
Page 16 of22
Pl.2 Ch.5 Lifting
4. STRUCTURES
4.1.3 Lift points
4.1 DESIGN CONDITIONS
4.1.1
~eral
4.1,.1.~ General recommendations regarding structural
design are given in Pl. 1 Ch.4.
4.1.1.2 Loadcases and analysis of forces are described
in Sec. 2. 4. For design of padeyes and other structural
elements, additlona1 design factors as described in 4.1.2
should be applied:
)
4.1.1.3 Tolerances which may result in an exeessive
lateral load components or skew loads should be
avoided.
4.1.3.1 Lift points and their attachments to the
structure should be designed for the maximum sling
load, any possible sling angles in addition to a lateral
loads as specified in 2.4.3.3.
4.1.3.2 Lift point designs which may fail as a result of
a moderate deviation in sling force direction should be
avoided.
4.1.3.3 Lift points should, unless lateral loading is not
particularly considered, be positioned so that the design
loads acts in plane with the main padeye plate.
4.1.2 Load factors
4.1.3.4 It is recommended that padeyes are designed
with the main connections in shear rather than tension.
High tension loads in the thickness direction of steel
material should be avoided.
Applying the partial coefficient method for the design,
the load combination ".an J see Pt.] Ch.4 Table 3.1 1 will
be governing. The total design factor given in Table 4.1
should be applied directly for design pUrPoses. Tho
design factor is defined according to Eq. 4-1.
Guidance·Note
Padeye plat~s are recommended sloHed through horizontal flanges
and welded directly to vertical web plates. If through tIlickness
tension can not be avoided, materfaIs with guaranteed through
thickness properties should be used, or Inspections of the material
to verify the through thickness properties shall be performed.
Eq.4-1
4.1.4 Lifting equipment
where
YdQip :
1, :
yc
:
4.1.4.1 For verification of spreader bars or spreader
frames a design factor.• 'Ydai&n' of 1.3 is 'acceptable for the
design factor
load factor
consequence factor
self weight of the equipment.
4.1.4.2 Eccentricities considering maximum possible
devintioDsin sling angles should be duly considered in
spreader bar verifications.
)
LIft points IncludIng attachments
to object (single critical elements
supporting the 11ft points is
1:3
1.3
1.7
4.1.5 Lifted object
defined ~hin thls category).
UfUng equipment (e.g. spreader
frames or beams, plate shackles).
1.3
1.3
1.7
Main eiements supporting the Un.
point.
1.3
1.15
1.5
1.3
"(c i meant to account for severe consequences of single element
failure. C8~egorisatlon of elem~nts according to the table above
should hence duty consider redundancy of elements.
4.1.5.1 Lifted objects should be verified for the
loadcases described in 2.4.
4.1.5.2 Appropriate design ractors, see Table 4.1,
should be applied to primary and secondary structural
elements
4.1.5.3 Due considerations should be paid to the skew
load cases as the load effects caused by these load cases
are normally not covered by in service design
conditions.
4.1.5.4 Attention should be paid to possible horizontal
load components at the lift points.
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.S Lifting
January 1996
Page 17 of 22
4.1.6 Bumpers and guides
4.2.2 Inspection
4.1.6.1 Bumpe... and guides should be designed
according to requirements in PI.1 Ch.2 Sec.5.4.
4.2.2.1 inspection of lift points and lifting equipment
should comply with the requirements given to for
"special structural ,teel" in Pt. 1 Ch.4 Soc. 4. 2.
4.1.7 Lay down arrangements
4.1.7.1 The lifted object .ball be equipped with a lay
down arrangement for tbe lifting equipment.
4.1.7.2 The arrangement shall provide for an easy lay
down of the rigging. and support the lifting equipment
both for static and horizontal/vertical dynamic loads
before and after lifting.
)
)
Dynamic loads to be considered may be transportation
loads. impact loads (from the lifting equipment) and
environmentnlloads after installation.
4.2.2.2 Lift point sball be inspected for eacb
subsequent lift. Lift points can be accepted for
subsequent lifting with a visual inspection if;
a)
the load history (since last MPIIUT inspectiOD) of
the lift points are known.
b)
no excessive or uncontrplled loading of the lift
points has occurred, or are suspected occurred
during previous lifts, and
c)
DO damages are revealed during tho visual
inspection.
Lift points satisf'ying items b) and c) only. sbould be
subject for minimum 20% MPI before any subsequent
lifting.
4.1.8 Seafastening and grillage
4.1.8.1 Requirements for design of seafastening and
griUage for transportation is in general covered in Pr.2
Ch.2 &c.2.3.2.
4.1.8.2 The seafastening and grillage sbould allow for
easy release and provide adequate support and horizontal
restraint until the object can be lifted clear of the
transportation vessellbarge.
4.1.8.3 Elements providing horizontal andlor vertical
support after cutting lremoval of seafastening shall be
verified for characteristic environmental conditions
applicable for tbe operation.
4.1.8.4 Seafastening .o f slings. spreader bars and other
lifting equipment shall be provided for rigging installed
during tbe tl1lllBport. Special considerations sball be
made for easy release of lifting equipment before lifting.
Welding to special elements sball be avoided.
4.2 FABRICATION AND INSPECTION
4.2.1 Materials and fabrication
4.2.1.1 Materials and fabrication of lift points and
lifting equipment should comply witb the requirements
given to for "special structural steel" in Pr.1 CiI.4
Soc.4.2.
)
On NORSKE VERITAS
January 1996
Page 18 of22
()
Rules for Marine Operations
PI.2 Ch.5 Lifting
S. LIFT OPERATION
5.1 CRANE AND CRANE VESSEL
5.1.4.2 Instructions for crane operation including
limiting parameters for crane operation (wind speed,
5.1.1
roll/pitch angles, etc:) sball be presented.
~eral
5.1.1."- The crane, crane vessel, and all associated
equipment sho.uld be in good condition, properly
manned and fit for performing the intended operations.
)
5.1.1.2 The crane should be equipped with a reliahle
load monitoring system with an accuracy normally not
exceeding 5% of the maximum crane capacity or 10% of
the weight of the lifted object.
5.2.1 Clearances during operation
5.1.2 Positioning
systems, back up systems. configuration layout etc.
5.1.2.1 The crane vessel should be moored and/or
positioned according to requirements in Pt. 2 Ch.7.
5.2.1.2 The calculated minimum clearances between the
For moorings combining anchors and short lines to shore
the requiremeots in Pt. 1 CII.2 Sec. 5. 3 apply.
5.2.1.1 Clearances during crane vessel operations
should be decided on the basis of the expected duration
of the operation, the operational procedure, tbe
environmental conditions, positioning and fendering
lifted object or lifting equipment and the crane boom
sbould normally not be less than 3m.
5.2.1.3 The calculated minimum clearances between the
lifting equipment pc the crane boom and any other
5.1.3 Crane vessel certificates
object/structure should normally not be less than 3m.
5.1.3.1 The crane vessel shall comply with the
requiremeots in Pt. 1 Ch.2 Sec.5.2.
5.2.1.4 The calculated minimum clearances between the
lifted object and any other object/structure shall be
evaluated based on evaluations of duration of the
operation, the operational procedure, the environmental
5.1.3.2 Hydroststic stsbility dats should be available
onboard.
)
5.2 OPERATIONAL ASPECTS
5.1.3.3 The following certificates should normally be
presented:
Certificate of Registry.
Certificate of Classification.
Safety Constructioll Certificate.
Certificate of International Load Line.
Safety Equipment Certificate.
5.1.4 Crane documentation
5.1.4.1 The following certificates for the crane should
normally be presented:
Certificate of classification or makers certificate.
Crane test and installation report issued by n
recoguised authority.
utest annual survey report.
Lift record for preceding operations.
Load-radius curves for static and dynamic lifting
conditions.
conditions, fendering systems, etc.
Guidance Nole
.
For-objects to be lifted over, around or between other objects a
minimum clearance of 3m is r~ommended.
5.2.1.5 Clearances between the underside of the lifted
object and grillage or s..fastening structures on tbe
transport vessellbarge should be evaluated. If tbese
clearance are small, particular atlention should be given
to avoid damages in case of impacts during lift off.
5.2.1.6 Clearance betweeo the lifted object or transport
vessellbarge and the crane vessel or crane boom should
be calculated.
The calculated clearance shoJ.lld consider motions of
crane vessel and transport vessellbarge. Clearance shall
be based on the environmental design conditions for the
operation and with a maximuQl values calculated
according to Pl. 1 Ch.3 Sec. 2.
Clearances less than 3m should normally be avoided.
)
DET NORSKE VERITAS
January 1996
Page 19 of22
Rules for Marine Operations
Pt.2 Ch.5 Lifting
5.2.1.7 Sufficient bottom clearance betWeen the crane
vessel and the sea bed should be present for lifting
operations at small water depths (inshore).
5.2.2 Lifting
5.2.2.1 Operational criteria such as, wind speed. wave
conditions? relative motions, etc., should be established
prior to starting the lifting operation. These criteria
should be included in the operation manual.
Guidance Note
lift off from another vessellbarge offshore should normally not be
performed with Hs greater than 2.0 - 2.5m. Relative vertical motion
between crane hook and lift off vessel should be carefully evaluated
before commencement of the lift. Relative motions exceeding 2m is
not recommended.
5.2.2.2 Crane vessels with favourable motion
characteristics may operate in relatively rough sea
conditions. For lifts carried out by such vessels,
considerations should be given to the effect of wind
loading, t6 ensure that such loads will not jeopardise the
operation.
5.2.2.3 The crane hook shOUld be positioned accurately
over the centre of gravity of the lifted object prior to
commencement of the lift.
Guidance Note
When lifting from another vessellbarge or rrom shore by crane
vessels, possible restraint loads be~en crane vessel and Ufted
object should be relieved by slackening mooring lines as much as
possible and restricted use or thrusters.
5.2.2.4 Ballasting of transportation vesselfbarge prior
to or duripg lifting in order to obtain simultaneous lift
off at all "support points should be considered.
(, 1
~ I
5.2.2.5 If counterweights are to be used to adjust the
centre of gravity during lifting, such weights should be
properly fastened to the lifted object.
5.2.2.8 For lifting of objects that are arranged with
shims between the support structure/grillage and tbe
object, the shims should be secured to one of the
surfaces. Alternatively a check point for removal of
shimming plates under the lifted object should he
included. Removal of shims should preferably he
performed immediately after lift off.
5.2.3 Monitoring of lifting operations
5.2.3.1 Where applicable the fol1owing parnmeters
should he monitored manually or by monitoring systems:
Hook load(s)
Environmental conditions.
TIlt (specially for multihook lifts)
Positipn and orientation.
Clearances.
Hoisting velocity.
5.2.4" Cutting of seafastening
5.2.4.1 The cutting procedure should be such that no
vertical restraint will occur during lift off.
Guidance Note
Verticalcutling of seafastenln9 with a flam~ cutter may, due to the
coarse cut. result in restraint effects. A beHersolution i~ to cut In
an angle of minimum 10 -15 degrees with the vertical axis or remove
one piece by applying two cuts.
5.2.4.2 Rotational restraint, at single support points,
e.g. module footings~ shall be avoided.
5.2.4.3 Cutlines should be marked on the seafastening
in advance.
Guidance Note
To avoid damaging the barge deck and provide for sare and easy
handU",g,considerations should be made to avoid large pieces or
loose searastenlng debris. Seafastenlng or large loose seafastenlng
or grillage debris after lift off should be considered.
5.2.2.6 For lifting of objectS with eentre of gravity far
from the centre axis between the lift points cOll5iderable
differenees in the sling angles and loads wiu occur. In
this case due attention should be paid to the eccentric
crane hook. It shall be documented that moment due to
the eccentric loading will not overload the Q.ook or
blocks, or make rotation of the hook impossible.
5.2.2.7 Rotation of the lifted object shall be
control1able in both directions during all phases of the
lift. This may be obtained by use of guiding/tugger
lines or guides/fenders. These systems shall be designed
according to requirements in Pt.] Ch.2 Sec.5.4.
DET NORSKE VERITAS
January 1996
Page 20 of 22
Rules for Marine Operations
Pt.2 Ch.5 Lifting
6. YARD LIFTS
6.1 GENERAL
6.2.4 Skew loails
6.2.4.1 Yard lifts may involve three or more cranes.
6.1.1 Application
6.1.1.1 This section applies for lifts and other crane
assisted operations (roll·up) in connection with erection .
and assembly. This section also applies for load out and
load in operations by onshore cranes.
6.1.1.2 Relevant requiremeots in Ilhrough 5 applies
for major yard lifts, roll-up operations and load out
operations by lifting. This section describes exemptions
and additional requirements for such operations.
)
Extreme crane loads , i c. worst possible load
distributions within the cranes, should be calculated
considering at least;
support lay-<>ut defined by the cranes,
flexibility of the lifted object,
crane types,
limiting environmental conditions,
lifting procedure and
monitoriog system/tolemoces.
A sensitivity analysis coDBidering possible crane load
variations should be considered.
6.2.4.2 The des'gn of lifting equ'pment should in some
cases be based on the crane extreme load capacity, e.g.
overtu~g load for crawler .crane.
6.2 LOADS
6_2.1 Weight and CoG
6.2.1.1 The weigbt of a yard lifted item is often based
on ealculations only. In such ""'ie the expected weigbt
should be multiplied with a contingency factor of
minimum 1.1 when defining the design weigbt.
Guidance Note
This Is partlcular1v relevant (Dr lifting with several highly utilised
crawler cranes, where exact crane load may be difficult to control.
6.2.5 Additionalloads
6.2.1.2 The effect of extreme positions of the CoG
6.2.5.1 For multi cmoe lift operations the maximum
should be evaluated.
put of plumb of hoist Iioes should be definedlealculated
and considered in the calculations.
6.2.2 Special loads
6.2.5.2 The effect of possible swinging of the lifted
6.2.2.1 F.or roll-up operations special loads may be of
object due to cmoe movements (travelling) should be
evaiuated.
great importance and should be thoroughly evaluated.
)
6.2.6 Loadcases
6.2.2.2 As applicable, special loads for roll up
operations are;
winch/tugger line loads,
support reaction loaas (vertieal and horizontal)
friction loads (at supports and 'lings) and
wind loads.
6.2.6.1 Loadcases for yard lifts should be selected
based on the general guidelioes given in 2.4 and the
loads described in the paragraphs above.
6.2.6.2 For multi cmoe operations sensitivity analy,is
with respect to possible crane load distributions, see
6.2.4.1, should be carried out.
6.2.3 Dynamic loads
6.2.3.1 Table 2.1 gives applicable factors to take into
account dynamic effects for onshore lifts.
6.2.3.2 For crawler cranes travelling with load,
6.2.6.3 For roll·up operations it should be justified that
the selecied lo.denses, i.e. analysed roll-Up angles,
represent the design case for J cranes, rigging and all
stroctural items.
possible dynamic effects should be evaluated thoroughly.
Crane speeds and surface conditions should be
considered.
DEl' NORSKE VI!RITAS
o
Rules for Marine Operations
Pt.2 Ch.S Lifting
January 1996
Pnge21 of 22
6.5.1.2 It should be documented that regnlar
mainteoance is carried out of all parts important for the
safety of the lift.
6.3 LIFTING EQUIPMENT
6.3.1 Slings and grommets
6.3.1.1 The nominal safety factor for slings and
grommets for yard lifts should be calculated as described
in 3.1.2.2.
Guidance Note
Yards slings are nannalty multiple used slings exposed to wear and
tear, hence a wear factory", > 1.00 should be used. Ay",=1 .20 Is
recommended.
6.3.1.2 Slings made of soft ropes could be acceptable,
see 3.1.104.
)
6.3.1.3 Due allention should 'be paid to the effect of the .
object rotation (roll·up) on the sling connections.
6.5.2.1 Allowable crane loads should be based on
Load·radii curves/tables. These should, as applicable,
clearly ,tate
crane boom type and length (crawler cranes),
counter weight position(s) and weights, minimum
quantity of hoist line legs, maximum load limited
by overturning or stnlctural strength,
Cral).C equipment, ~.g. hook, block, hoist lines,
jib, to be included in crane hook load and
operatipnal limitations.
6.5.2.2 For multi crane operations as roll-ups and lifts
involving travelling, eff~tive crane radii should be
calculated considering maximum out of plumb for hoist
lines. The crane capacities should be calculated based 00
these radii, see 6.2.5.
6.3.2 Shnckles
6.3.2.1 Shackles with SWL " 50 tonnes without
certificate may be acceptable provided;
SWL is stamped on the shackle,
shackle fabricato~ is recognised,
calculated dynamic shackle load" SWL, and
the ,hackle i, thoroughly inspected before use.
6.5.2.3 Acceptable ground strength should be
documented for crawler crane operations. Special
attention should be given to the toe. peak loads. If
necessary capacity tests should be carried out.
6.5.2.4 Operational limitations for travelling counter
weights should be considered. Position and weight, e.g.
water/sand filled, ,hould be checked.
6.4 SfRUCTURES
6.4.1 Lift points
6.4.1.1 The local strength capacity for some not
pUl1'ose, built lift points, such as tubular members, may
have a huge strength reserve, j.e. the load causing local
failure is much greater than the elastic load capacity. A
design factor of 1.3 may in these cases be applicable, see
TObie 4.1 .
Guidance Note
Typical examples are ,eJastic hoop stresses for a tubular member
where supporting a sling, compared with the total plastic capacity of
the hoop.
6.5 CRANES
6.5.1 Documentation
6.5.1.1 Normally yard cranes should be in possession
of an approval statement issued by a recognise4
authority.
Guidance Note
In Norway this Is ~Arbeidsti1synet·.
6,5.2 Allowable loads
6.6 OPERATIONAL ASPECTS
6.6.1 Clearances
6.6.1.1 For yard lifts, when all effects are accounted
for, a calculated minimum clearance to the crane boom
of O.Sm i, normally acceptable.
Guidance Note
For roU-up operations planned holst line angles need to be
considered when the minimum clearances are calculated.
Possible deviations from vertical holst lines, see 6.5.2.2, need to be
considered when establishing minimum clearances for lifts lnvofving
traveUing.
6.6.1.2 A thorough check for obstructions in way of
the cranes, the structure and rigging should be carried
ouL
6.6.1.3 Crane tracks should be marked and the surface
levelled/improved if required.
DET NORSKE VERIrAS
Rules for Marine Operations
Pt.2 Ch.S Lifting
January 1996
Page 22 of 22
6.6.1.4 For roll-up operations the monitoring should
include;
lifted object deflections,
hoist line angles,
crane positions,
reaction loodslbehaviour in roll up ceUs and
roll-up angle.
Seealso 5.2.3.
)
(
)
DET NORSKE VERITAS
RULES FOR
PLANNING AND EXECUTION OF
MARINE OPERATIONS
PART 2: OPERATION SPECIFIC REQUIREMENTS
(
)
n
PART 2 CHAPTER 6
SUB SEA OPERATIONS
JANUARY 1996
SECTIONS
1. INlRODUcrrON .................. ..... ......... .................................................................................... 4
2. DESIGN LOADS .... •.........................................•........ .............. .......... ..... ..•................. ..... •...... 8
3. SOIL CAPACITIES ........... .. ....•....•..................... ... ........ ..... .... .................... .. .... .. .................... 13
4. OPERATIONAL ASPECfS ....... ............ .•....... ... ...... ... .......... ... .. .....................•.....•............•...... 15
, )
DET NORSKE VERITAS
Veritasveieo I, N-1322 H3Vik, Norway Tel.: +47675799 00, Fax.: +4767579911 '
()
CHANGES IN THE RULES
This is the first issue of the Rules for Planning and
Execution of Marine Operations, decided by the Board
of Del Norske Veritas Classification AlS as of December
1995. These Rules supersedes the June 1985, Standard
for Insurance Warranty Surveys in Marine Operations.
These Rules come into force on lsi of January 1996.
This cbapter is valid until superseded by a revised
chapler. Supplements to this chapter will not be issued
except for minor amendments and an updated list of
corrcctions presented in the introduction bookJet.
Users are advised to check the systematic index in the
introduction booklet to ensure that iliat the chapter is
current.
)
)
)
@
Det Nord:e Veritaa
Computer Typc&euing by Oet NOllike Veritu
printed in Norway by the Det Noo;;k.e Verius janusI)' 1996
1.96.600
()
Rules for Marine Operations
Pt.2 Ch.6 Sub Sea Operations
January 1996
Page 3 of 18
CONTENTS
1.
INTRODUCTION ...••..... •.•••• ... .•.... •.. ..... . 4
1.1
GENERAL ...................... ... ......... . ......... 4
1.1.1 Application ............. ..... ........ .......... 4
1.2
DEFINITIONS ....................................... 4
1.2.1 Terminology ...... ......................... .... 4
1. 2. 2 Symbols ........................................ 4
3.
SOIL CAPACITIES .............................. 13
PLANNING .......................................... 5
1.3.1 Critical design parameters ................... 5
1.3.2 Docu.mentation ........... ...... ........ .. ..... 5
1.3.3 Preparations ....... ................. ..... ...... 6
3. 1
ON BOTTOM STABlllTY .. ................. .... 13
3.1.1 General ............................... ...... ... 13
3.1.2 Stability calculations ............... . ........ 13
3.1.3 Material factors .................. ........ .... 13
1.4
LOADS ......................... ....... ................ 6
1.4.1 General .. ........ ...... .... ...... ..... .. ........ 6
1.4.2 Environmental loads ...... .... ........ .. .. ... 6
1.4.3 Hydrostatic loads ............................. 6
1.4.4 Positioning loads ............................. 6
1.4.5 Loads from soil ............ .... . .. .......... .. 6
1.4.6 Other loads .. .. .. .. ..... .... ......... .. ........ 7
3.2
PULL OUT FORCES .............................. 13
3.2.1 Retrieval of object. ......... ................. 13
3.2.2 Time for full drsinage ...................... 13
3.2.3 Downward forces - drsined puD .......... . 13
3.2.4 Downward forces - undrsined pull ..... ... 14
3.2.5 Downward forces - retrieval by pumping 14
3.2.6 Effect of filters ................... . ........... 14
1.5
STRUCTURES ....... . .. ........ .. .... ......... ...... 7
1.5.1 General ........ .. .... .................. .... ..... 7
4.
OPERATIONAL ASPECTS .................... 15
4. 1
GENERAL ... ... .... ........... ..... ........ .. . .. .... 15
4.1.1 Application .. .................. ...... .. ....... 15
4.1.2 Planning and preparations .................. 15
2.
DESIGN LOADS ........ ............ .. ...... ....... 8
2.1
GENERAL ............................................ 8
2.1.1 Application ....................... , ............ 8
4.2
CRANE TIP MOTIONS ........ ... ................. 8
2.2. 1 Characteristic vessel motions ...... ... . .. ... 8
2 .2.2 Characteristic crane tip motion .. .......... _ 8
2.2.3 Characteristic crane tip velocity ............ 8
2.2.4 Characteristic crane tip acceleration ....... 8
SysTEMS ........................................... 15
4.2.1 Load reducing systems ........ .............. 15
4.2.2 Dynamic positioning systems .............. 15
4.2.3 Ballasting systems ......... ...... ............ 15
4.2.4 Manned vehicles and ADS-systems. : ..... 16
4.3
INSTALLATION AlDS ....... .. ... . .. ........... .. 16
4.3.1 General . ......... ............... ......... ...... 16
4.3.2 Guide and tugger lines ............ .......... 16
4.4
ROV OPERATIONS .. ...... ............... .. ...... 16
4.4. 1 Planning .... ........ ........ ................... 16
4.4.2 General recommendations ............. . .... 16
4.4.3 Launching restrictions ............ .......... 17
4.4.4Monitoring .. ... .............. .. .......... .. :. 17
4.5
TIE-IN OPERATIONS .... .. .......... ... ..... .... 17
4.5.1 ROV recommendations .. .... ........... .. .. 17
4.5.2 Other recommendations ......... ........ .. . 17
4.6
BUNDLE OPERATIONS ......................... 17
4.6.1 Bundle transport ...................... ....... 17
4.6.2 Pipeline and bundle pull-in .. ...... .. .... .. 18
2.2
~
OrnER LOADS ... . . ... . .. ....... ... .. . ........ .. .. 12
2.6.1 Pull down and pull in ....................... 12
2.6.2 Mating and impact forces .................• 12
2.6.3 Off-lead and side-lead forces ..... .. ....... 12
2.6.4 Current forces on ROV ............. ........ 12
1.3
) )
)
2.6
/
2.3
.,.)
2.4 .
2.5
HYDRODYNAMIC FORCES WHEN
LOWERED THROUGH WATER SURFACE. 9
2.3 .1 Characteristic total force ...... . .... .. .. ...... 9
2.3.2 Characteristic hydrodynamic force ......... 9
2.3.3 Characteristic slamming impact force .... . 9
2.3.4 Characteristic buoyancy force . .......... . .. 9
HYDRODYNAMIC FORCIlS ON
SUBMERGED OBJECTS ......................... 10
2.4.1 Characteristic total force .................... 10
2.4.2 Characteristic hydrodynamic force ....... . 10
2.4.3 Effect of moon-pool.. ... ............... ..... 11
SNAP FORCES IN HOISTING LINE .......... 11
2.5.1 General ........... .. ..... .......... ............ 11
2.5.2 Characteristic snap force ........ ......... .. 11
2.5.3 Characteristic snap velocity ................ 11
DEI' NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.6 Sub Sea Operations
January 1996
Page 4 of 18
1. INTRODUCTION
Significallt wave height: four times the standard
deviation of the surface elevation (close to the average of
the one third highest waves) in a short term. wave
condition.
1.1 GENERAL
1.1.1 Applieation
1.1.1.1 'This PI.2 Ch.6 Sub Sea Operations present
guidelines for sub-sea installation operations, applicable
for gravity based sub sea structures, tie-in operations,
production manifolds, templates, B.O.P. '5, wellhead
)
protection structures, etc,
Zero crossing wave period: average wave period, i.e.
average time period between water surface elevate
through the still water level.
1.1.1.2 PI.2 Ch.6 applies to objects being lowered,
pulled down or ballasted from the sea surface to its final
position on the seabed.
1.2.2 Symbols
1.1.1.3 Recommended practice for lifting oPerations in
air are covered in PI.2 Ch. 5.
1.1.1.4 General requirements and guidelines in Pr.1 of
these Rules applies for sub sea operations. This chapler
is complementary to PI.1.
1.1.1.S Conditions for using these Rules are stated in
Pr.D Ch.l Sec.1.2.
1.2 DEFINITIONS
1.2.1 Tenninology
)
Snap force: snatch load in hoisting line due to sudden
velocity ch"llge of lifted object.
1.2.1.1 Definitions of terms are included in Pr.D Ch.1,
Terms considered to be of special importance for this
chapter are repeated below.
Characteristic condition: a condition which, together
with load and material factors, yield a defined
probability of exceeding structural capacity within a
defined time period, see also Pr.1 Ch. 3 Sec. 2. 1.
Design loads: the load or load condition which form
basis for the design and design verifica~ion.
Design sea state: the short term wave condition which
form basis for the design and design verification.
Natural period: the period of which the vessel will
move in still water.
Short tenn wave condition: a wave condition where
significant wave height and zero crossing wave period
are assumed constant in the duration time, typically 3
hrs.
1.2.2.1 The list below define symbol' used within this
chapter;
Effective cross section area of line.
A,:
Cross sectional area of moon-pool.
A",p:
Area of object projected on a horizontal plane.
Ap:
Area of object penetrating the water surface,
Aps
projected on n horizontal plane.
Projected cross sectional area of ROV.
Characteristic single amplitude vertical
acceleration of crane tip.
Characteristic vertical water particle
a..:
acceleration.
The horizontal distance -from the vessel's
b:
centre line to the crane tip, or the outboard
,heave block.
Drag coefficient.
Cd:
Added mass coefficient.
em:
Slamming coefficient.
C. :
Coefficjent of consolidation.
Cv :
DAF : Dynamic amplification factor.
Distance from water plane to centre of gravity
d:
of submerged part of object.
Diameter of submerged cable,
Modulus of elois!icity.
Load eccentricity.
e:
Characteristic buoyancy force.
Fp:
Horizontal current force on ROV.
FCir :
Chara1:teristic drag force.
Fd:
Horizontal force on effecUve area.
F HI :
Characteristic hydrodynamic force.
F.,. :
Characteristic mass force.
Fill:
Forces on object when pulled down in lock-in
Fpd :
. position.
Characteristic slamming impact force.
F.Lun:
Static submerged weight of object.
FlItIIlic:
Vertical load.
Fv:
Acceleration of gravity.
g:
Significant wave height of design sea state.
H,:
DET NORSKE VERITAS
)
)
Rules for Marine Operations
Pt.2 Ch.6 Sub Sea Operations
January 1996
Page 5 of 18
h:
Drainage distance.
on bottom visibility,
k~.dc:
Stiffness of wire(s), strop. crane boom. etc.
K:
Stiffness of hoisting system.
Length of line(s).
The horizontal distance from midship to the
current profile,
wave/wind statistics for area in question,
L:
I:
crane tip. or the outboard sheave block.
Projected length of submerged cable.
Moment loading at base level.
m:
Mass of object in air.
Added mass of object.
Drained resistance, mainly caused by friction
Q,:
Suction force due to negative pore pressures in
on embedded elements (skirts, etc.),
the soil, as reaction to short term pulling
forces, caused by vessel heave motioDs.
I) I
Q,.:
)
o
Downward forces from the foundation in case
of a drained pUJl out.
Sliding resistance on area outside effective
area : s.(A-A ').
Sliding resistance due to horizontal soil
pressure on embedded member.
TH :
Tp:
T.:
t,.:
V:
Heave natural period.
Pitch natural period.
RoJl natural period.
Time for full drainage.
Vc; :
Volume of displaced water.
Hook lowering velocity.
Va:
Characteristic single amplitude vertical
vn.p :
p:
1m:
11rt:
II )
type of operation,
type of installation vessel/equipment,
tide,
design sea state,
vessel response characteristics,
type of lifting gear,
crane capacity and specifications,
crane tip motioo,
crane hoisting/lowering speed,
hydrostatic and hydrodynamic effects,
trapped air,
submerged weight,
tugger line angle forces,
sea bed suction forces,
sen bed topography and soil parameters, and
load reducing systems.
1.3.1.2 Design criteria should be considered in relation
to the operation reference period, see Pt. 1 ClJ.2 Sec.3. J
and waiting on weather probabilities.
1.3.2 Documentation
velocity of crane tip.
VI:
expected time Decessary to complete operation,
expected time to reverse operation,
Maximum current velocity.
Free fall velocity, see 2.5.3.4.
Characteristic vertical relativ~ 'velocity
between object and water particles.
Characteristic slamming impact velocity.
Characteristic snap velocity.
Density of sea wate~.
Material factor.
Characteristic single amplitude vertical motion
pf crane tip.
Characteristic single nmpJitude heave motion
of vessel.
Characteristic single amplitude roll motion of
vessel.
Characteristic single amplitude pitch motion
of vessel.
1.3.2.1 The sub-sen operation should be described by
detailed procedu(es and drawings, and documented with
calculations, see also Pt. 1-Ch.2 Sec.2.2.
1.3.2.2 A manual covering the sub-sea installation shall
be prepared
1.3.2.3 Detailed contingency procedures for each
critica1 operational step should be worked out in order to
establish environmentaIlimits for possible
recovery/retrieval, see 4.1.2.
1.3.2.4 Technical specifications for equipment such as
cranes, lifting gear, constant tension winches, heave
compensators, etc. should be referred to in the
installation procedures.
1.3.2.5 Mation response characteristics for installation
vessels related to design and operational weather criteria
1.3 PLANNING
should be documented.
1.3.1 Critical design parameters
1.3.2.6 Prior to start of the operation, certificates, test
reports, release notes and classification documents if
1.3.1.1 When evaluating a sub-sea operation, the
following parameters should be taken into account prior
to establishing the design and operational criteria, see
Pt.1 Ch.2 Sec. 3. 1;
any, for equipment and vessels involved, should be
presented as applicable.
water depth,
DET NORSKE VERITAS
n
January 1996
Rules for Marine Operations
Pt.2 Ch.6 Sub Sea Operations
Page 6 of 18
1.3.3 Preparations
1.3.3.1 The soil parameters should he detennined, in
order to estimate impact loads, suction loads and holding
capacity.
1.3.3.2 The extent of site surveys should be determined
in relation to type, size and complexity of the object to
be ins!Rlled , and the sea bed properties.
1.3.3.3 10 selecting the size of area to be investigated,
sufficient tolerances should be included to account for:
errors in navigation equipment used for
installation, and
realistic operational tolerances.
)
1.4.2.3 Hydrodynamic loads on submerged object
should be calculaled according to Sec.2. Alternatively a
2D or 3D analysis and/or model tests may he carried
out in order 10 establish the hydrodynamic coefficients
more accurately. Impact loads, viscous effects and other
non- linearity's should also be considered
1.4.3 Hydrostatic loads
1.4.3.1 Hydrostatic and buoyancy loads should be
taken according to Pt. ! CIr.3 Sec.3.6.
1.4.3.2 Hydrostatic pressure loads on submerged object
due to;
1.3.3.4 The required accuracy for differential elevation
measurements, should be considered. Possible
scourlbuild-up caused by current should be investigated.
1.3.3.5 A survey giving n qualitntive description of the
bottom topography at the install~tion site should be
carried out prior to the sub-sea operation, in order to
monitor obstacles such as boulders. anchors, debris, etc.
Normally a side scan survey should be canied out some
lime before Ibe operation, followed by a more detailed
ROV survey shortly prior to installation.
external water pressure
differential pressures in ballast chambers
should be considered.
1.4.3.3 Maximum expected external water pressure for
objects and compartments should normally be mUltiplied
'by 1.1 for on bottom opemtions, and by 1.3 for
operations taking place sub-surface.
At the design stage a realistic centre of buoyancy
envelope shall be considered.
1.4.4 Positionilljlloads
1.4.4.1 Positioning loads related to trllDBlation and
rotation of the object during lowering , positioning and
setting should be considered.
1.4 LOADS
1.4.1 General
)
1.4.1.1 Characteristic loads and load combinations
should be established according to Pt. ! Ch.3.
1.4.1.2 Design loads and load cases shall be taken
according to Pt.! Ch.4.
1.4.1.3 Static weight and weight distributions should be
taken according to Pt.! Ch.3 Sec.3,5.
1.4.2 Environmentalloads
1.4.5 Loads from soil
1.4.5.1 Reaction forces from the soil should be
aecoup-ted for. Londs such as foundation reactions at
seabed impact and during the soil penetmtionlretraction
pbase, and suction forces When repositioning of an
object is required, should be determined considering tbe
following parametersj
soil material and parameters
sea bed topography
penetration depth and
exposure time (repositioning)
1.4.2.1 Environmental loads should be determined in
accordaocewith Pr.1 Ch.3 Sec.3 and 2.
1.4.2.2 For wave loads on installation vessel, all
relevant wavelengths, and corresponding zero upcrossing
periods, including swell type wave lengths, should be
considered.
DET NORSKE VERITAS
(
Rules for Marine Operations
Pt.2 Ch.6 Sub Sea Operations
)
January 1996
Page 7 of 18
1.4.6 Other loads
1.4.6.1 When relevant, due consideration should be
given to special loads such as;
tugger line loads,
off·lead and side-lead loads,
londs due to redistribution of ballnst,
current loads on ROV,
trapped air, and
other r.elevant loads.
1.5 STRUCTURES
1.5.1 General
1.5.1.1 The internal structural integrity of the object to
be installed and any temporary attaciuoenls, should be
desigoed to withstand hydrostatic, hydrodynamic and
any other temporary load during traosportation and
installation.
1.5.1.2 Structural strength should be verified according
to Pt.1 ChA .
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Drr NORSKE VERITAS
January 1996
Page 8 of 18
Rules for Marine Operations
Pt.2 Ch.6 Sub Sea Operations
2. DESIGN LOADS
I :
2.1 GENERAL
2.1.1 Application
2.1.1.1 This section presents recommendations for
determination of operational and environmental load
the horizontal distance from midship to the crane
tip, or the outboard sheave block [m]
2.2.2.2 The values for characteristic single amplitudes
in heave, roll and pitch for the crane vessel arc to be
taken as absolute values.
2.2.2.3 The values for characteristic single amplitudes
in heave, roll and pitch for the crane vessel should
represent the largest characteristic responses when all
possible wave periods Tr; for the given significant wave
beight H. are considered.
effects.
2.2 CRANE TIP MOTIONS
2.2.1 Characteristic vessel motions
()
2.2.3 Charnct...istic crane tip velocity
2.2.1.1 The characteristic motions for the installation
vessel should be established- for the environmental design
condition, either by a refined analysis, or by acceptable
documented simplified calculations.
2.2.3.1 The crane tip's characteristic vertical velocity
for a given design sea state may be taken as:
For further explanation of the term II characteristic t1 • see
Pt.1 Ch.3 Sec. 2. 1.
vn =21t
2.2.1.2 For subsea operations d,cpeodent on a fixed
vessel heading. vessel responses for all wave headings
shall be analysed.
where
o
(;:J' +(b'i~~'PR)r +(lsi~~'Pp)r
Eq.2-2
2.2.1.3 Por subsea operations that may be performed
independent of ·v essel headings. the Wlalysis of vessel
responses may be limited to headings within the beading
tolernnces in a one failure situation.
)
2.2.2.1 The crane tip's characteristic vertical motion
response in a given design sea state and wave heading,
may be talren as:
where
TJH:
CPR:
'Pp :
b:
2.2.4 Chamct...istic crane tip acceleratinn
vertical acceleration for a given design sea state JllQ.y be
taken as:
+(bSin~<p.))' + (lsin<;p»)'
( T1~1'
T,J
. T.
T,
+ (bsin('PR>)' + (lsin(,pp}),
Eq.2-1
11c:t :
TH :
T. :
Tp :
characteristic single amplitude vertical velocity of
crane tip
[mls]
beave natural period
[sJ
roll natural period
[5J
pitch natural period
[5J
2.2.4.1 The crane tip's cbaracteristic single amplitude
2.2.2 Characteristic crane tip motion
1l~ ; ~1l~
vel:
characteristic single amplitude vertical motion of
crane tip [m]
characteristic single amplitude heave motion of
vessel [m]
characteristic single amplitude roll motion of
vessel [deg]
charneterislic single amplitude pitch motion of
vessel [deg]
the horizontal distance from the vessel's centre
line to the crane tip, or the outboard sheave block
[m]
Eq.2-3
where
Sa :
characteristic single amplitude vertical
accelerati2,n of crane tip
)
DlIT NORSKE VERITAS
[mls1
o
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Rules for Marine Operations
Pt.2 Ch.6 Sub Sea Operations
January 1996
Page 9 or 18
2.3 HYDRODYNAMIC FORCES WHEN
LOWERED THROUGH WATER SURFACE
2.3.3 Characteristic slamming impact force
2.3.3.1 The characteristic slamming impact force on the
of the object when penetrating the water surface
may be taken as:
bottom
2.3.1 Characteristic total force
2.3.1.1 The characteristic ta:tal force on object when
lowered through water surface may be taken as:
F.Jam= 0.5 pC. Ap VIZ
FtIXa.I= F tUttic: ± Fbyd
where
Eq. 24
where
F~c: : static submerged weight of object
[N]
Fbyd :
[N]
characteristic hydrodynamic force
Eq.2-7
density of sea water, normally =1025 [kgfm'j
slamming coefficient which may be determined by
theoretical and/or experimental methods. For
smooth circular cylinders C. should not be taken
less than 3.0. Otherwise, C. should not be taken
less than 5.0.
area of clements penetrating the water surface.
projected on a horizontal plane
[m]
[mI_]
slamming impact velocity
p:
C. :
2.3.1.2 The slatic submerged weight of object is given
by:
)
Q
')
Ap :
F""", = mg- pVg
Eq.2-5
where
m:
g:
p:
V:
mass of object in air
[kg]
acceleration due to gravity = 9.81
[mls>:!
density of sea water, normally = 1025 [kgfm'l
volume of displaced water during different ~tages
when passing through the water surface
[m
v. :
2.3.3.2 The slamming impact velocity may be
calculated by:
v. =
~v~ +3lH. [0528(
4
. .)-0...
4v,
~v' +31H
+ 1.645]+ V,
Eq.2-8
2.3.1.3 For objects that may emerge after submergence,
the possibilities of an increased weight due to entrapped
water shall be considered.
where
Vet:
v.:
H, :
crane tip velocity, see Eq . .2-2
hook lowering velocity, typically 0 .50 [mls]
Significant wave height of design sea state
2.3.1.4 Snap forces in lifting wire will occur if
hydrodynamic force exceeds static submerged weight of
object, see 2.5.
2.3.4 Characteristic buoyancy force
2.3.4.1 The lifting force acting on the object due to
2.3.2 Characteristic hydrodynamic force
buoyancy forces during surface penetration phase may be
taken -as:
2.3.2.1 The characteristic hy.drodynamic force on
F, = mg[1 +~g (I
object when lowered through water surface may be taken
as:
[N]
pgA p )(K)' .]
(K+pgA,) m
Eq.2-9
F.,.=F..... + Fp +F..... + F""""
Eq.2-6
where
FI1am : characteristic slamming impact Jorce, see 2.3.3
Fp : characteristic buoyancy force. see 2.3.4
F..... : hydrodynamic drag loads.
F....,.: hydrodynamic inertia loads.
where
m : mass of object in air
[kg]
g:
acceleration due to gravity ?81
[mi.>:!
vr :
characteristic vertical ,relative velocity between
object and water particles
[mi.]
K:
stiffness of hoisting system
[NfmJ
=
2.3.4.2 The characteristic vertiCilI relative velocity
between object and water particles may be laken as:
v~ +3.1H.(/~:dr
v, =
[mls]
Eq. 2-10
where
d:
distance from water plane to centre of gravity of
submerged part of object.
[m]
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.6 Sub Sea Operations
January 1996
Page 10 of 18
2.4.1.3 Soap forces in lifting wire will occur if
hydrodyopmic force exceeds static submerged weight of
object. In such case, the dynamic amplification factor
should be taken as:
2.3.4.3 The stiffuess of the hoisting system may be
calculated by:
I
I
1
1
1
1
-=--+--+--+--+-K k,,,,, k"", k."", kboom k .....
Eq.2-11
where
K:
stiffness of hoisting system
[N/m]
k\l.il"t :
stiffness of single wire line
k.,,(l: .
stiffness of soft strop if used
stiffness of multiple wirelines in a block
stiffness of crane boom
other stiffness contributions if any
kblock :
kboom :
k....,:
Eq.2-15
where F. DIIP may be found according to 2.5.2..
2.4.2 Characteristic hydrodynamic force
2.3.4.4 The stiffness of craJie boom is often neglected
2.4.2.1 The hydrodynamic force on the object consists
of mass forces and drag forces which may be combined
by:
as it is usually much larger than the line stiffness'. The
line stiffness' may be calculated. by:
)
k=EA,
L
[N/m]
o
[N]
Eq.2-16
where
characteristic mass force
characteristic drag force
Pm:
[N]
[N]
Eq.2-12
F, :
[N/m']
2.4.2.2 The characteristic mass force due to combined
acceleration of object and water particles may be taken
as:
where
E:
A,:
L:
modulus of elasticity
effective cross section area of line, if multiple
lines the areas are summarised
[m1
total length of line(s)
[m]
[N]
Eq.2-17
where
2.4 HYDRODYNAMIC FORCES ON
SUBMERGED OBJECTS
m:
m".,. :
n,,:
2.4.1 Characteristic total force
2.4.1.1 Tho characteristic total force on object when
object is submerged may be taken as:
)
p:
v:
a.,:
mass of object in air
[kg]
[kg]
added mass of object
characteristic single amplitude vertical
2
[m/s ]
acceleration of crane tip, see 2.2.4
density of sea water, normally = 1025 [kglm1
volume of displaced water
[m1
char~cteristic vertical waler particle acceleration
[mil]
FtctaI = F5Iu1ic ± Fhyd
Eq.2-13
where
FroW,: static submerged weight of object, see 2.3.1.2[N]
Ph".: characteristic hydrodynamic force
[N]
2.4.2.3 ·The added mass of the object may be taken as:
m".,.
=
pVCm
Eq.2-18
where
2.4.1.2 The espacity of the lifting equipment should be
checked according to Pt.2 Ch.5 Sec. '1 applying:
D AF = F.12lic + Fbyd
F.1:I.1ic
Eq.2-14
where Fh,. may be found by Eq. 2-16.
em:
added mass coefficient as a function of depth,
which may be determined by theoretical andlor
experimental methods.
2.4.2.4 -The characteristic water particle acceleration
may be taken as;
(
032dJ'
a w = 31H, e-"""""'Hs'"""
)
[mls'
Eq.2-19
where
d:
distance from water plane to centre of gravity of
submerged part of object [m].
H.. : Significant wave height of design sea state
DEl' NORSKE VERITAS
c
Rules for Marine Operations
Pt.2 Ch.6 Sub Sea Operations
January 1996
Page 11 of 18
2.4.2.5 The characteristic drag force may be taken as:
Fc= 0.5 P Cd Ap v r
2.5.2 Characteristic snap force
2
Eq.2-20
where
Cd :
drag coefficient as a function of depth, which may
Ap :
be determined by theoretical and/or experimental
methods.
area of object projected on a horizontal plane[m'].
Vr:
characteristic vertical relative velocity between
2.S.2.1 Characteristic snap loads during start and stop
may be taken as:
Eq.2-22
where
~:':lcharacteristic snap velocity
[mls]
object and water particles, see 2.3.4.2 [mls].
~
see definitions 2.3.1,2.3.4 and 2.4.2
2.4.3 Effect of moon·pool
2.4.3.1 Characteristic hydrodynamic force when object
is lowered through a moon-pool may be computed in
accordance with 2.4.2 but with adjusted mass- and drag-
m""
2.5.3 Characteristic snap velocity
coefficients.
2.5.3.1 The snap velocity during start and stop may be
taken as;
2.4.3.2 The mass- and drag-coefficients em and Cd
should be substituted by fm em and fd Cd respectively,
maximum normal transport velocity. typically
1.0 mi.
V'Iap:
where:
fm =
fd =
1+1.9(AplAmp)2.25
2.5.3.2 The snap velocity occurring if hydrodynamic
forces exceed static submerged weight may be taken as:
I-OS(A, I Am,)
[1- (A, I Amp)]'
Amp ; cross sectional area ofmoon-pc;JOI
A, :
[m1
area of object projected on a horizontal plane [m'l
Eq.2-23
where
VI{:
free fall velocity, see 2.5.3.3
vr :
characteristic vertical relative velocity between
object and water particles, see 2.3.4.2
[mi.]
2.S SNAP FORCES IN HOISTING LINE
1
2.S.1 General
2.S.1.1 Snap force,
C=
F.~p
, mp.y be caused by sudden
=({~
. for Vff < 0.2V,
-02)) for 0.2V, < V"."< 0.7V,
o
velocity changes in the handling system due to start or
[mls]
for Vff
> O.7V,
stop, or by slack hoisting lines due to hydrodynamic
forces exceeding static submerged weight:
2.5.3.3 The free fall velocity of the object in calm
Fhyd > Flttltic
Eq.2-21
water may be"taken as:
where
F bl• and F..., are given by 2.3.1, 2.3.2 and 2.4.2.
v'C =
Eq.2-24
2.5.1.2 Snap forces due to large hydrodynamic forces
where
shall as far as possible be avoided. Weather criteria for
operation should be adjusted to ensure this.
see defInitions 2.3.1.2 and 2.4.2.5
2.5.1.3 Snap forces due to start or stop should be taken
into due considerations. Snap loads during start/stop
may be taken according to 2.5.2.1.
DET NOI\SKE VERITAS
n
Rules for Marine Operations
Pt.2 Ch.6 Sub Sea Operations
January 1996
Page 12 of 18
2.6 OTHER LOADS
2.6.4 Current forces on ROV
2.6.1 Pull down and pull in
2.6.4.1 The horizontal current force
the submerged cable may be taken as
2.6.1.1 Tho forces on a buoyant object being pulled
down by a line from the surface, via a sheave or similar
device on the sea bed, may be computed in accordance
with 2.4 and 2.5. For the final lock- in stage, see
2.6.1. 2.
2.6.1.2 When an object is pulled inldown, into lock-in
position on a sea bed structure, the pull force 00 the
object may he taken as:
Fp!
= 1.2 TJa K
00
the ROV and
F= = 6l5(d~"'~b+ARov) v= 2
[N]
Eq.2-26
where
d~b :
diameter of sUbmerged cable
leab: projected length of submerged cable
AROV : projected cross sectional area of ROV
v~:
maximum Cllrrent Velocity
[N]
[m]
[m]
[m1
[mls]
o
Eq.2-25
where
)
11a:
K:
verticnl crane tip motion, see 2.2.2.1
[m]
the stiffuess of the hoisting system, see 2.3.4.2
[N/m]
2.6.1.3 In general, the hoist line should constitute the
weak link in the system. Yielding capacity of attachment
brackets, e.g. attachment of hoist line to the objcct,
attachment of sheave to the bottom structure, etc.,
should as a minimum be 1.3 times the MBL of the
attached line.
2.6.2 Mating and impact forces
2.6.2.1 Horizontal and vertical impact velocity between
the object and sea bed or bottom structure, should
nonnally not be taken less than 1 [mls]. The maximum
vertical impact velocity need not be taken larger than the
free fall velocity of the object in calm ·water.
)
2.6.2.2 Positioning forces in vertical and horizontal
direction should normally not be takeo less than 3 % of
the installed object's submerged weight including added
o
mass.
Q
2.6.3 Off-lead and side-lead forces
2.6.3.1 Off-lead and side-lead forces are forces on the
lifting system occurring when the lifted object is pulled
away from the vertical through the crane tip. Off-lead
means in the direction away from the crane, and sidelead is perpendicular to the direction of the -crane boom.
2.6.3.2 Off-lead and side-lead forces should be
calculated with basis in current forces on the object and
the hoisting line and the consequent deviation from the
vertical through the crane tip, see 2.6.4.
DET NORSKE VERIT AS
January 1996
Page 13 of 18
Rules ror Marine Operations
Pt.2 Ch.6 Sub Sea Operations
3. SOIL CAPACITIES
3.1 ON BOTTOM STABILITY
3.2 PULL OUT FORCES
3.1.1 General
3.2.1 Retrieval of object
3.1.1.1 It should be documented that the object during
all phases of the installation operation remajns stable on
the sea bed, without getting unacceptable displacements
due to soil failure.
3.2.1.1 For re-positioning or retrieval of an object
placed 00 the sea bed, forces due to suction should be
calculated. This may be dODe by using bearing capacity
formulae as given in Classification Note 30.4. seaion
4.4.
3.1.1.2 A general rererence is made to Classification
NOle 30.4 Foundations for calculation of soil properties
3.2.1.2 The forces are dependent on soil parameters,
foundation geometry, lifting velocity, exposure time,
contact pressure, etc.
and capacities.
3.1.2 Stability calculations
3 .2.2 Time for full drainage
3.1 .2.1 Whether the permanent roundation solution is
based on mat roundation or piled foundation, there will
often be a temporary pbase during installation where the
object will be supported on mats, possibly equipped with
skirts.
3.2.2.1 The time for full drainage should be calculated
based on specific soil da~ for the site in question, in
order to plan the rate of pull application, and calculate
the corresponding foundation reactions.
3.1.2.2 The stability may for reasoDably homogeneous
soil conditions be checked by conventional bearing
capacity fonnulatioDs combined with pure sliding
checks. Recommendations are given for idealised soil
conditions in Classification Note 30.4. section 4.4.
3 .2.2.2 Time for full draioage may be taken as:
Eq.3-l
where
3.1.2.3 Stability should be checked for load
combinations including gravity loads, environmental
loads where significant, and any loads possibly applied
to the structure during installation, e.g. during stabbing
of piles.
3.1.3 Material factors
3.1.3.1 For foundation failures which may have
unaccepLable consequences, such as structural damage or
irrecoverable, unacceptable displacements, material
factor should be applied as follows:
Ym
=
'Ym
=
1. 25 on uDdrained shear strength for total stress
analyses.
1.25 on friction coefficient for effective stress
analyses.
3.1.3.2 For failure modes having less severe
consequences, lower material factors and/or load factors
may be used as agreed upon in each case.
h .=
Cv
=
drainage distance
coefficient of consolidation
A simple and conservative approach may be to assume
that all pulling forces applied within the time t,. is •
reacted by suction, whereas all pulling forces applied
earlier, effectively reduces the net foundation contact
forces. More elaborate consolidation analyses may be
performed to evaluate the partial draioage for the force
applied within the time t,..
3.2.3 Downward for= - drained pull
3.2.3.1 Downward forces from the foundation in case
of a drained pull out is thus:
Q",
= Q.+Q.
Eq.3-2
where
Q.
=
Q..
=
draioed resistaoce, mainly caused by friction on
embedded elements (skirts, etc.)
suction force due to negative pore pressures in the
soil, as reaction to short term pulling forces,
caused by vessel heave motions.
)
DET NORSKE VERIrAS
January 1996
Page 14 of 18
n
Rules for Marine Operations
Pt.2 Ch.6 Sub Sea Operations
3.2.3.2 The pulling forces caused by be-we of the
installation vessel should normally be considered to be
reacted by a suction force in any kind of soil, unless
consolidation analyses are performed to demonstrate that
drainage occurs.
3.2.6.2 The soil reaction may be difficult to calculate
aod may depend on tbe filler used (permeability,
structural flexibility t etc.). The soil reaction should on
tWs case be documented by appropriate tests, or actual
experience for similar conditions.
3.2.3.3 For seabed conditions mainly consisting of
sand, it will normally be possible to provide a drained
pull- out. The time for application of the pulling force
shou14 be planned to assure drained condition. see 3.2.2.
3.2.3.4 A total drained loading condition may require
the use of a heave compensated crane.
3.2.4 Downward forces - undrained pull
3.2.4.1 In soils rich on clay, it wiD genernUy not be
possible to assure drainage for the pulling forces within
)
a reasonable time for a repositioning operation. In order
to break the foundation base out of the soil, a·reversed
bearing capacity failure will have to be developed.
a
3.2.4.2 If lifting takes place some time after initial
p1acement of the object, the effect of consolidation on .
the shear strength of the soil should be considered.
3.2.4.3 For Short lerm ilynamic forces, an increased
undrained shear strength due to loading
should be considered.
Tate
effects
3.2.5 Downward forces - retrieval by pwnping
3.2.5.1 An object base equipped with skirts sbould
)
preferably be retrieved by pumping waler into the skirt
compartment. In such case only the soil resistance
against the skirts may be considered. The friction against
the skirts may be related to the undrained shear strength
of the soil nod should be determined based on tbe actual
soil investigati~ms for the site.
3.2.5.2 The effect of remoulding and reconsolidation of
the soil should be considered.
3.2.6 Effect of mlers
3.2.6.1 The use of a filler attached to the centre base of
the foundation. connected to a draining system, may
significaolly reduce the required pull due to suction. The
soU reaction force may be reduced to the force
corresponding to ripping the filter off the soil, plus a
small suction to allow flow through the draining system.
)
DET NORSKE VERITAS
OJ
)
n
January 1996
Page 15 ofI8
Rules for Marine Operations
Pt.2 Ch.6 Sub Sea Operations
4. OPERATIONAL ASPECTS
4.1 GENERAL
4.1.1 Application
4.1.1.1 tbis section applies for plaoning and execution
of sub-sea installation operations. General requirements
for planning and preparations are given in Pt. 1 Ch.2.
4.1.2 Planning and preparations
4.1.2.1 Detailep contingency procedures for each
operational step should he worked out. Special
consideration should be given to retrieval/abandoning
procedures in case of deteriomting weather conditions.
4.1.2.2 For sub-sea operations intended to be
100%
diverless, the possibility of having other methods standby as a contingency/back-up, should be considered.
where found applicalile ..
4.1.2.3 If applicable integration testing sbould be
carried oul. For complex and critical stages of the
installation dependant 00 ROV, the operator's skill
should be verified.
4~2.2.3 Maximum utilisation of DP system during
operation should not exceed 80% of total capacity. If the
utilisation exceeds the 80% level, the vessel should be
taken into a stand-off/stand-by mode. Weather criteria
for the 80% limit should be established and documented.
4.2.2.4 Should a staDd-off mode be impossible,
preparations for abandoning or retrieval of object should
be made in due time prior to reaching the 80% limit. In
any case, the installation vessel's station keeping
capability should not be influenced if break down of any
one of the thrusters should occur. Exemptions from this
recommendation, is subject to approval from attending
VMO surveyor.
4.2.2.5 Minimum clearances between DP vessel and
any fixed or floating structures shall be defined based on
characteristic environmental conditions for the operation,
DP class of vessel and the Environmental Regularity
Number (ERN).
4.2.2.6 Sub-sea operations dependent on more than one
DP vess~l, should have a clearance between vessels of
not less than 5000. Operations requiring leSs clearance
will he evaluated in each case. DP alarm sbould
normally be set to maximu~ ±2m.
4.2 SYSTEMS
4.2.3 Ballasting systems .
4.2.1 Load reducing systems
4.2.3.1 For operation, requiring ballasting of the.
4.2.1.1 Based upon technical specifications. onsite
evaluations, or other documentation, operational credit
may. on a case to case basis be granted by the 'attending
VMO surveyor. Hence n more severe weather
condition may be acceptable.
object, a proper ballast control and monitoring system
should be implemented. Special back_up/monitoring
devices in order to avoid uncontrolled ballasting m1i.y be
'
required.
4.2.3.2 Ballast systems utilising external umbilical
4.2.2 Dynamic positioning systems
supply, are subject to the same recommendations as
outlined in 4.3.1.2.
4.2.2.1 When DP is used for station keeping. a
4.2.3.3 All panel valves to be operated by ROY.. should
minimum of 3 independent DP reference systems are
required.
he clearly ......ked open/shut (O/S). Valve indicators on
critical valves may be cpnsjd~red nccc;ssary for visual
verification purposes.
Guidance Note
For operations where consequences for handled object, installation
vessel and other structures or vessels In the vicinity, of loosing the
DP reference systems ,are small, 2 Independent reference systems
may be accepled.
4.2.3.4 Special back up or monitoring equipment may
be required in order to avoid uncontrolled ballasting
4.2.2.2 DP reference systems sensitive to interference
from radar, radio, telex etc. should not be used du:ring
critical phases of sub-sea operation.
DEr NORSKE VERITAS
n
January 1996
Page 16 of 18
Rules
4.2.4 Manned vehicles and ADS-systems
Marine Operations
4.4 ROV OPERATIONS
4.2.4.1 Atmospheric diving systems (ADS). sbould in
general incorporate adequate back·up. enabling 24 hours
operability.
4.2.4.2 Operational reliability should be documented
through presentation of dive logs, maintenance records
etc.
4.2.4.3 It should be documented that tbe ADS system is
capable of operating under the given design and
operational criteria.
4.3 INSI'ALLATION AIDS
)
4.3.1 General
4.3.1.1 Installation aids should be located such tbat
they are not damaged during preceding operations, e.g.
lifting of structures. bandling of piles etc.
4.3.1.2 The connection of the object to pre<installed
base/template or similar I should preferably avoid the use
of external gaslbydraulie supply from surface for locking
purposes, unless means are provided reducing the risk of
mechanical damage to a minimum during the lowering!
positioning phase, and sufficient back up is accounted
for.
4.3.2 Guide and tugger lines
4.3.2.1 Guide wires/tugger lines sbould be used in
order to prevent rotation of the structure during
)
fOI"
Pt.2 Ch.6 Sub Sea Operations
installation.
4.4.1 Planning
4.4.1.1 When planning for a sub sea operation. the
following ROV limitations and recommendations should
be noted:
Wire cutting tiy use of ROV requires slack wire.
ROV working range, i.e. max. horizontal offset.
ROV operations on moving objects should
normally not be considered feasible.
The operational influence of the ROV operator's
skill aad experience should be reduced.
ROV tracking system by means of transponders
should he subject to commissioning.
For complex ROV operations full scale
qualification tests shall be considered. Contractor
shall demonstrate ROV capability of executiog the
planned intervention.
4.4.1.2 The stability ofROV during operation sball be
considered. A ROV docking frame sball be used if
possible.
4.4.2 General recommendations
4.4.2.1 ROV downtime. both planned arid unforeseen.
should be taken into consideration when establishing
required weather window.
4.4.2.2 Sub-sea operations. totally dependent on ROV.
should be equipped with at least two independent ROV
spreads. ROV crew enabling 24 hours operability should
be provided. Sufficient spares should be available.
Prior to acceptance afROY operations, maintenance
records and dive logs for each ROV should be presented.
4.3.2.2 For multi book lifts. active use of tuggerlines
may be omitted. These sh9U1d however be preconnected.
4.4.2.3 Complex operations which are totally
dependeot on the skill of the ROV operator sbould
preferably be avoided.
4.3.2.3 If guide/pull-down lines fixed to a pre·installed
sub- sea template or similarf will require a fixed vessel
beading, the weather criteria specified for the operation
should reflect this.
4.4.2.4 ROV thruster capacity should normally be at
least 30% higher thaa the maximum expected current
force actiog on the ROV and its umbilical.
4.3.2.4 Temporary attachments whicb may impose
damage 'to the structure, should be removed without
delay.
4.4.2.5 MeaoSfor localising and tracking of the ROV
from the surface may be required.
.
4.4.2.6 For operations combining ROV and divers, any
possible restrictions that ROV and divers are nO_l able to
work siniultaneously, should be clarified in advance, and
taken into due consideration.
DET NORSKE VERIT AS
o
()
Rules for Marine Operations
Pt.2 Ch.6 Sub Sea Operations
January 1996
Page 17 of 18
4.4.3 Launching restrictions
4.5.2 Other recommendations
4.4.3.1 Launching and retrieving of large ROV's, not
protected by cage, over a ship's side should not take
place in waves exceeding H.>2.5-3[m].
4.5.2.1 Procedure for abandoning babitat should be
documented, as well as limiting criteria for station
keeping of vessel. Abandoning of babitat in case of
deteriorating weather conditions should normally not
take longer than the time necessary to retrieve divers.
4.4.3.2 If exemptions from restriction in 4.4.3. J is
made, it must be documented that ROV's can be
retrieved Of launched in a safe manner under more severe
conditions.
4.4.3.3 Moon-pool ROV operations may however be
extended to
H.
<
4.5.2.2 For tie-in operations taking place in water
depths> ISO[mj, means should be, provided for
reducing tension and drag in umbilicals) unless sufficient
internal strength and vessel station keeping capability is
documented.
5-6m, depending on the actual motion
characteristics of the vessel in question.
~.6
4.4.4 Monitoring
BUNDLE OPERATIONS
4.6.1 Bundle transport
4.4.4.1 10 general, means should be provided enabling
monitoring of all sub-sea operations, e.g. ROV, diver
carried video. etc. Any critical part of the operation
.involving risk for damage, should not be performed
4.6.1.1 General requirements to tugs are given in Pl. 2
Ch.2 Sec. 3.3.
without such monitoring.
4.6.1.2 As a minimum, lead tug, trailing tug, stand-by
rug, and bundle monitoring vessel are required.
4.4.4.2 All diving and complex Work-ROY operations
should be monitored by independent ROV.
4.6.1.3 The requirements to the various vessels are:
4.4.4.3 ROV used for monitoring of sub sea operation
should be operated from the installation vessel.
Guidance Note
The requirements in 4.4.4.3 may ,be.dispensed from where large
horizontal distances between lnstall;3t1on vessel and the observation
ROV is required.
Regardless of theoretically required bollard pull
(BP), the lead tug and stand-by tug should have a
minimum BP of70 tonnes, and the trailing rug 35
tonnes, in direction of pull.
lt is recommended that all vessels are preferably
equipped with DP systems.
The Jrailing tug should be equipped with towing
winch forward.
4.5 TIE-IN OPERATIONS
Towing winches should be equipped with
adjustable overload protection.
4.5.1 ROV recommendations
There should be two drums on the towing winch.
4.5.1.1 Positioning operations of habitat and Pipe
Handling Frame (PHF) should he subject to monitoring
by ROV. For positioning operations sensitive to vessel
motion, limiting weather criteria should be established.
4.5.1.2 Location of ROV onboard vessel should be
chosen with due ,consideration to umbilicals, wires etc.
attached to habitat and PHF, in order to avoid
entangling. Back up ROV fot monitoring should be
present opboard.
4.6.1.4 All tugs should bave suitable towing
arrangements for 'piggy back' connection in case of
engine break down/failure.
4.6.1.5 Bottom survey for towing route should be
carried out. Holding areas for each 100 n.mile with a
diameter of at least the bundle length +200m to be
surveyed.
4.6.1.6 Maximum allowable pull-head angle with
surface should be documented.
4.6.1. 7 Maximum towing speed should generally not
exceed 4 knots. Higher speed may be allowed, but will
be subject to satisfactory bundle behaviour during first
part of tow.
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DEi- NORSKE VERITAS
January 1996
Page 18 of 18
Rules for Marine Operations
Pt.2 Ch.6 Sub Sea Operations
4.6.1.8 Two towing lines sbould be fitted at each end
of bundle. whereof one to be regarded as emergency
towing wire. Emergency wire should be pre-connected
to emergency towing winch.
4.6.1.9 Means for monitoring of bundle configuration
during tow to be provided. Depending OD the operational
reliability, back- up system may be required.
4.6.1.,10 It should be documented lbat the bundle has
sufficient internal strength, enabling the bundle to hang
freely supported at each end.
)
4.6.1.11 Routing requirements:
Pipeline crossings should be reduced to a
minimum.
Current forces should be taken into due account
when establishing low route.
Weather window should reflect the choice of
towing route.
Approach corridor to location should be
establi,hed.
Possible fishing activity lo be taken into
consideration.
o
4.6.1.12 Procedure for internal ballasting or
presrurising of bundle to be documented.
4.6.1.13 Detailed abandonment procedure, including
anchoring of bundle to be established.
4.6.2 Pipeline and bundle pull-in
)
4.6.2.1 It is assumed that integration tests, if
applicable, have verined the operability of the various
tools and equipment. Test reports should highlight and
reflect critical operational sequences and their limiting
factors.
4.6.2.2 10 genc(al, procedures for the below listed
operational sequences shoJ.tld be established, inclucling
contingency p1ans, and limiting weather criteria:
Pull in lool installation/retrieval
Connection tool installation/retrieval
Pull head disconnection/retrieval
Connection of pull bead wire to pulJbead
Guide wire installation
F1oodin,g of bundle
Chain and buoyancy tank. removal
4.6.2.3 Suitable arrangement for release of towing wire
from pull head to be provided.
)
DET NORSKE VERITAS
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()
RULES FOR
PLANNING AND EXECUTION OF
MARINE OPERATIONS
PART 2: OPERATION SPECIFIC REQUIREMENTS
()
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PART 2 CHAPTER 7
TRANSIT AND POSITIONING OF MOBILE OFFSHORE UNITS
JANUARY 2000
SECTIONS
(
)
I.
2.
3.
4.
INTRODUCTION ................................................... ,. ...................................................•.......... 4
PLANNING AND PREPARATIONS ................................................................................. :... 6
TRANSIT ................................................................................................................................. 7
POSITIONING ........................................................................................................................ 9
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DET NORSKE VERITAS
Vcritasveien 1, N-1322 H¢vik, Norway Tel.: +47 67579900, Fax.: +47 67 57 99 11
CHANGES IN THE RULES
This is the first issue of Pl.2 Ch.7 of the Rules for
Planning and Execution of Marine Op~rnlions, decided by
the Board of Det Narske Veri las as of December 1999.
These Rules supersede the June 1985, Standard for
Insurance Warranty Surveys in Marine Operations.
This chapter is valid until superseded by a revised
chapter. Supplements to this chapter will not be issued
except for minor amendments and an updated list of
corrections presented in the introduction booklet.
This chapter comes into force on 1st of January 2000.
Users are advised to check the systematic index in the
introduction booklet to ensure that the chapter is currcnt
)
)
)
e Det Norskc Veritas
Compu1ctTypesetting by Det Norskc Vcritas
Printed in Norway by the Det Norske VerilllS Januruy 2000
1.00.600
Rules for Marine Operations
Pt.2 Ch.7 Transit and Positioning of Mobile Offshore Units
January 2000
Page 3 of 16
CONTENTS
I.
INTRODUCTION .........................................••••• 4
4.
POSmONING ....................................•.......•...... 9
1.1
GENERAL ........................................................... 4
1.1.1 Application ............................................... 4
4.1
1.2
DEFINITIONS ..................................................... 4
1.2.1 Terminology ............................................. 4
1.2.2 Symbols .................................................... 5
GENERAL ........................................................... 9
4.1.1 Positioning ....... ......................................... 9
4.1.2 Environmental conditions ......................... 9
4.1.3 Documentation ............................,"""",.". 9
4.2
STATION·KEEPING SYSTEMS .................... , \0
4,2.1 General ................................................... 10
4.2,2 Design requirements ............................... \0
4,2.3 Mooring systems ..................................... 10
4,2.4 Dynamic Positioning (DP) systems ........ \0
4,3
CLEARANCE .................................................... II
4.3.1 General ................................................... 11
4.3.2 'Clearance for synthetic fibre rope lines .. 11
4.3,3 Clearance during positioning .................. 11
4.3.4 Clearance during short·term operations .. 11
4.3.5 Clearance in ntmnal operation ... ...... ....... 11
4,4
INSTALLATION OF ANCHORS ..................... 12
4.4.1 General ....................... ,........................... 12
4.4.2 Drag·installed anchors ............................ 13
4.4.3 Other anchor types ..................... ............. 13
4.5
POSmONING OF SELF·ELEVATfNG UNITS 13
4.5, I Genernl ................................................... 13
4.5.2 Clearance .... ,........................................... 14
4.5.3 Seabed conditions ................................... 14
4.5.4 Operational aspects·................................. 14
4.5.5 Jackirg operations .................................. 14
4.5.6 Testing .................................................... 14
2.
PLANNING AND PREPARATIONS..............• 6
2.1
PLANNING ......................................................... 6
2.1.1 General ..................................................... 6
2.1.2 Co·ordination ............................................ 6
2.1.3 Documentation .......................................... 6
)
2.2
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)
DESIGN EVALUATIONS .... .............................. 6
2.2.1 General ..................................................... 6
2.2.2 Stability afIoal.. ........................................ 6
2.2.3 Loads and load effects .............................. 6
2.2.4 Strength ev.aluations .................................. 6
3.
TRANSIT ............................................................ 7
3.1
GENERAL ........................................................... 7
3.1.1 Transit operation ....................................... 7
3.1.2 Documentation .......................................... 7
3.1.3 Tug assisted transit operations .................. 7
3.IA SelfpropeUed transit operations ............... 7
3.2
TOWING EQUIPMENT ..................................... 8
3.2.1 General ..................................................... 8
3.2.2 Required thrust and ballard pull ............... 8
3.2.3 Emergency anchoring ............................... 8
3.3
OPERATIONAL AsPECTS ................................ 8
3.3.1 General ..................................................... 8
3.3.2 Emergency jack up locations .................... 8
Table list
Table 4.1 - Minimum clearance ....................................... 15
Table 4.2 - Verification of resistance of drag-instailed
anchors ........................................................ 16'
DEI' NORSKE VERITAS
Rules for Marine Operations
January 2000
Pt.2 Cb.7 Transit and Positioning of Mobile Offshore Units
Page 4 of16
1. INTRODUCTION
Coastal towing - Towing in waters less than 12 nautical
miles off the coastline.
)
1.1 GENERAL
Dry transport - Transportation of a mobile offshore unit
1.1.1 Application
as deck cargo on a barge or a heavy lift carrier. The tenn
Dry tow may also be used for transport of a unit as deck
cargo on a barge.
1.1.1.1 PI.2 Ch. 7, Transit and Positioning of Mobile
Offshore Units provides specific requirements and
recommendations for transit and positioning of:
semi submersible units
self-elevating units
floating storage units
drilling ships
floating producdon units
and for positioning of offshore installation vessels.
Inshore towing - Towing in sheltered waters.
In this chapter, the term "unit" is used in general for these
vessels.
1.1.1.2 General requirements and guidelines in PI.] of
these Rules apply for transit and positioning operations.
This chapter is complementary to Pt,l.
1.1.1.3 Reference is made to PI.2 Ch.3 for transit
operations by heavy lift carriers and to Pt.2 Ch.2 for
transit as deck cargo on barges ("dry transport"). For onand oftloading of heavy lift carriers or heavy lift barges,
reference is made to Pt.~ Ch.i.
)
1.1.1.4 For operation of units under nonnal conditions,
reference is made to the relevant parts ofDNY's "Rliles
for Classification of Mobile Offshore Units", or the
equivalent rules of other recog~ised bodies.
Guidance Note
By normal condition are meant 1he condItion stated In the
Classification Certificate of the unit, and covered 'by Its
Opemtions Manual.
1.1.1.5 Conditions for these Rules are slated in PI.D Ch.i
Sec.i.2.
1.2 DEFINITIONS
1.2.1 Terminology
1.2.1.1 Definitions of terms are included in the PI.D
Ch.i. Terms considered to be of special imporlance for
this chapter are repeated below.
)
Dynamic positioning (DP) - A method of automatically
controlling a vessels position within certain predefined
tolerances by means of active thrust. This active thrust is
provided by thrust units that arc controlled by computers.
The purpose of thi s active thrust is to counter the
environmental forces such as wind, waves and current
such that the vessel will maintain it's required
geographical position.
Bollard pull- Continuous static towing force applied by
tug, i.e. continuous tow line force.
Internal seafastening - Securing of loose items within the
unit.
Long-term mooring - Mooring at the same location for
more than 5 years.
Operating condition -The condition in wh,ich the unit
carries out its nonnal functions, e.g. drilling, and which is
within the operational limitations and preconditions set for
the condition.
Offshore towing - Towing outside territorial waters more
than 12 nautical miles off the coastline.
Operation reference period - Planned operation period
plus estimated contingency time. See Pt.1 Ch.2 Sec.3.i.i.
Positioning - The activities necessary for getting in
correct position and establishing the station-keeping
system of a floating uni~ or jacking up a self-elevating unit
at a new location.
Seafastening - Structural elements providing horizontal
and uplifl support of objects onboard the unit during the
transport.
Short-term operation - An operation that can be
completed within a reliable weather window, i.~. a
weather restricted operation.
Survival condition - The condition in which the
operational limitations (maximum allowable wind velocity
and/or motion of the unit) for the relevant operating or
transit condition have been exceeded, andlor in which the
measures necessary for the condition have been taken.
Temporary safe condition - A condition where the unit
can 'sustain the environmental loads corresponding to the
10~year seasonal condition, or the characteristic
environmental condition/loads corresponding to 30 days
exposure period, determined according to PI.! CIL3 Sec. 2.
DET NORSKE VERITAS
()
Rules for Marine Operations
Pt2 Ch.7 Transit and Positioning of Mobile Offshore Units
Total thrust capacity· Total continuous thrust capacity
available. i.e. sum of unit's own thrust capacity and tU1fs
thrust capacity.
Transit - The activities necessary to move a floating unit
from one location to another at sea, either by towing or
self propelled.
Unrestricted opera/ions - Operations with characteristic
environmental conditions according (o' iong-leon
statistics, i.e. with no environmental restrictions to
execution of the planned operation.
Verification - Activity to confirm that a design,
produclfequipment. structure or procedure complies with
defined standards andlor specifications. Verification may
be documented by calculations, analysis, certificates.
survey reports and inspection reports.
')
)
Weather restricted operations - Operations with defined
restrictions to the characteristic environmental conditions,
plaoned to be perfonned within the period of reliable
weather forecasts.
WeI tow - Self floa~ing towing of a mobile offshore unit,
as opposed to Dry tow.
1.2.2 Symbols
The list below defines symbols used in this chapter:
Hs:
HAT:
LAT:
MBL:
MOU:
MWL:
NMD:
ROV:
SSCV:
Significanl wave height
Highest astronomicallide
Lowest astronomical tide
.Minimum breaking load
Mobile offshore unit
Mean water Jevel
Norwegian Maritime Directorate
Remote operated (submersible) vehicle
Semi-submersible crane vessel.
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DETNORSKE VERITAS
January 2000
Page 5 or 16
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Rules for Marine Operations
January 2000
Page 6 of 16
Pt2 Ch.7 Transit and Positioning of Mobile Offshore Units
2. PLANNING AND PREPARATIQNS
2.1 PLANNING
2.2.2 Stability anoat
2.1.1 General
2.1.1.1 ' Transit and positioning operations shall be
planned and prepared according to the requirements and
philosophies given in Pt.! Ch.2.
2.1.2 Co-ordination
2.1.2.1 Several operations may be planned to take place
in the same area at the same time, and will require coordination between the various vessels and operators in
order to avoid conflicts.
This is in particular important for positioning and
sub~sea
operations in the same area.
2.2.2.1 General' stability requirements are given in PI.]
Ch.2 Sec.4. However, compliance with the stability
requirements of the actual Flag State andlor the
classification society is sufficient, and is normally covered
in the operations manual or the stability manual of the
vessel.
2.2.3 Loads and load effects
2.2.3.1 Characteristic loads and load effects shall be
defined according to Pt.! Ch.3 Ser:.3.
2.2.3.2 Load cases for the transit and positioning
operations shall g~nerally be defined according to PI.]
Ch4 Sec.2.2.
2.1.3 Documentation
2.1.3.1 General requirements for documentation are
given in Pt.1 Ch.2 Sec.2.2.
)
2.2.3.3 Possible impact loads during selling of selfelevating units shall be cons'idered.
2.1.3.2 The phmned transit or positioning operation shall
be described by procedures and drawings.
2.2.4 Strength evaluations
A ,manual covering the relevant aspects of the operation
shall be prepared, see also Pt.! Ch.2 Sec.2.2 and Pt.!
Ch.2 Sec. 3. 5.
Pt.! ChAo
2.1.3.3 Certificates, test reports and classification
documents for equipment, objects and vessels involved
shall, as applicable, be presented before start of the
operation.
2.2.4.1 Structural strength venfication shall comply with
2.2.4.2 The transit condition of the unit shall be
confinncd to be within the conditions for class, or.
otherwise the l.niil shall be verified to have acceptable
strength for the transit conditions. See also Pt.! Ch.3 and
pt.'J Ch.4.
2.2.4.3 Special attention shall be given to structural
integrity of legs and their supports of self-elevation units,
both in transit and due.ing positioning.
2.2 DESIGN EVALUATIONS
2.2.1 General
2.2.1.1 General requirements for design of transit and
positioning operations are given in PI.] Ch.3 and PI.}
ChAoAdditional and specific requirements for design of
transit and positioning operations are given below and in
Sec.3 and Sec.4.
2.2.4.4 Seafastening of loose items and non-permanent
cargo carried onboard shall comply with Pt.2 Ch.2
Sec.2.3.2 or Pt.2 Ch.3 Sec.2.!.6, as relevant.
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DET NORSKE VERITAS
Rules for Marine Operations
January 2000
Page 7 of 16
Pt.2 Ch.7 Transit and Positioning of Mobile Offshore Units
3. TRANSIT
3.1 GENERAL
3.1.1 Transit operation
3.1.1.1 Transit is defined as the activities necessary for
moving a floating unit or self-elevating unit from one
geographicallocalio.n to another location. The transit
operation is regarded as initiated when release of the
mooring lines or jacking down has conunenced. The
transit operation is regarded as completed when the unit as
arrived at the new geographical location and the
positioning/mooring operation commences.
the operations manual for the unit
stability calculations for the unit in relevant modes
of the transit condition
general arrangement plan
certificates for all components of the unit's towing
gear
diagrams showing:
wind force as function of wind velocity
current forces as function of current
velocity
wave drift forces in relation to significant wave
height and period
specification of thrust provided by the unit's own
propulsion machinery, if fitted.
3.1.2.4 Helicopter deck and other exposed structure shall
have sufficient clearance to avoid contact with waves in
floating condition.
3.1.2 Documentation
3.1.2.1 As part of the planning of a transit operation
documentation covering the following aspects shall be
prepared:
design and operational weather conditions for the
transit route at the season for the intended transit
calculations of the characteristic loads on the unit
during transit
verification of acceptable structural capacity of the
unit and its equipment.
Guidanc~ Note
Generally. a weather-unres1ricted transit of a self-elev!3tlng unit
can only be performed as a Mdry transport".
3.1.3 Tug assisted transit operations
3.1.3.1 Transit operations may be performed a~ lowing
operations or as tug assisted transit operations where the
unit's own thrust capacity is 'utilised. See 3.2.2 for
required propulsion force.
3.1.4 Self propelled transit operations
3.1.4.1 For units with own propulsion machinery, transit
operations may be performed without tug assistance.
»)
3.1.2.2 Particulars of the following items shall be
presented for review prior to the operation;
arrangement of the towing equipment
fairleads and fastening devices fQr towline
supporting structures
permanent towing equ'ipment, chain cables, steel
wire ropes, shackles, rings, thimbles and flounder
plates
retrieving arrangement
emergency arrangement
particulars for the towing vessol(s), and
planned transit route with specification of:
narrows and shallow waters
statistical current conditions
weather conditions
port(s) of refuge
refuelling port(s)
intennediatc jack-up positions.
3.1.4.2 The propulsion force of the unit shall be
sufficient to maintain control under the environmental
conditions given in PI.2(;k2 8.ec.3.3.2.4 andSec.3.3.2.5.
Notc that for transit-in coastaVnarrow waters a minimum
speed ovc_r the ground of2 knots in the environmental
design condition shall be maintained, see Pt.2 (;/1.2
Sec.3,3.2.5.
Guidance Note
DNV classed mobile offshore units with additional class notation
DYNPOS wl)h letter T, AUTS. AUT. AUTR or AUmO \\ill
noimally comply with the above requirement for propulsion force.
Guidance Note
In some cases National govemmental regulations may require
tug assistance regardless of the unit's oWn propulsion force.
3.1.2.3 In addition to 3.1.2.2. the following plans or
ipfonnation shall be available;
DET NORSKE VERITAS
Rules for Marine Operations
January 2000
Page 8 ofl6
Pt.2 Ch.7 Transit and Positioning of Mobile Offshore Units
3.2 TOWING EQUIPMENT
3.2.1 General
3.2.1.1 General requirements for towing vessels. towed
unit and towing equipment are given in PI.2 Ch.2 Sec.3.
3.2.1.2 Requirements for the capacity of towing bridle
and towing brackets are given in PI.2 Ch,2 Sec.3.1.
Guidance Note
For some mobile offshore units these requirements may be In
excess of what is required by its class. Normally, compliance with
class requirements will suffice.
.
Guidance Note
For ·wet tow" of self-elevating units the environmental criteria for
5e"ln9 Bfe oHen stricter than the criteria for towing, i.e. the
criteria for setting win govern the decision for entering into a safe
hold condition.
3.3.2 Emergency jack up locations
Guidance Nole
If the tug Is oversized (i.e. has considerably more ballard pull than
specified In 3.2.2.1). the required strength of the towing
arrangements including the brackets on the towed uniVVessel can
be reduced to comply only with the minimum bollard pull required.
In such cases a restriction on maximum ballard pull to be
exercised by the tug shall be given In the towing procedure, S88
2.1.3.2.
3.2.2 Required thrust and bollard pull
3.2.2.1 The combined propulsion force (total thrust
capacity) of the unitlvessel and the tug(s) shall be
sufficient to maintain control of the unit under the
environmental conditjons given in Pt.2 Ch2 Sec.3.3.2.4
and Sec.3.3.2.5. For transit in coastal/narrow waters a
m'inimum speed over the ground of 2 knots in the
environmental design condition shall be maintained, see
PI.2 Ch,2 Sec.3.3.2.5. Propulsion efficiencies for tugs
shall be accounted for with reduction factors as given in
PI.2 Ch.2 Sec.3.3.2.6.
3.2.3 Emergency anchoring
)
3.3.1.2 Criteria for entering into a safe hold condition,
related to aclual and forecasted environmental conditions
shall be clearly stated in the operations manual. The
criteria shall reflect necessary time for reaching the safe
condition, including required contingency time, see also
PI.l Ch2 Sec.3.1. Reference is also made to 3.3.2 for
towing of jack-Ups.
3.2.3.1 The unit shall normally -have at least one operable
anchor during transit. The anchor(-s) is to be of sufficient
capacity and with sufficient length of mooring line
available for emergency anchoring.
Guidance Note
The lack of an operable anchor system may be compensated by
additional tug capacity., after evaluation of characteristics of the
unit, towing route and season.
3.3 OPERATIONAL ASPECTS
3.3.1 General
3.3.1.1 General requirements for towing operations are
. given in PI.2 Ch,2 SecA.
3_3.2.1 For aself-elevating unit with limitations in the
environmental conditions it can sustain in floating
condition, transit operations shan be planned as weather
restricted operations with defined emergency jack up
locations. Distance between these locations will be
decided by required time for jacking down and jacking up
the unit, time for positioning and unit towing speed, plus
contingency time.
Guidance Note
The NMD regulations concerning field moves for Norwegian
flagged offshore units require .that maximum transit time between
the emergency jack up locations shall not exceed 24 hours. This
24 hours pertod covers Jacking down to floating condition, towing
and jacking up to sufficient air gap at the new location.
3.3.2.2 For defined emergency jack up locations it shall
soil conditions are such that the
be aocumented that
jack-up will not experience sudden significant penetration
of the spudcans during the jacking process or during the
stay at the location in elevated position. Soil conditions
with soft. normally consolidated clays or with stiff soil
overlying soft soil (punch-through conditions) shall be
avoided.
the
3.3.2.3 The documentation shall clearly show that the
locations .consist of competent soils which are either dense
sands or stiff clays to d.epth which excludes the possibility
of foundation punch-through.
3.3.2.4 The documentation shall include bathymetric
mapping and a shallow seismic survey for the location,
which can be tied back to nearby existing soil boring(s) to
assist :in the assessment of the soil slratigraptty. The
seismic survey shall be of good quality using equipment
which can Irace the shallow lay.ering and detect possible
presence of buried erosion channels within the depth of
interest, basically down to 50 m below seabed.
The seismic surveys, the soil borings and the
i~terpretation of the corresponding soil conditions for the
actual location shall be documented.
DET NORSKE VERITAS
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January 2000
Page 9 of 16
Rules for Marine Operations
Pt.2 Ch.? Transit and Positioning of Mobile Offshore Units
4. POSITIONING
4.1.2 Environmental conditions
4.1 GENERAL
4.1.1 Positioning
4.1.1.1 Positioning is defined as the activities necessary
for;
getting n floating unit in correct posilion at a new
location, and
establish its mooring system, or
connect the unit to a pre-laid mooring system. or
jacking up a self-elevating unit at a new location.
4.1.1.2 The positioning operation is regarded as
completed when;
a floating unit is moored with all anchors set and
tested and with all anchor lines connected and
tensioned, or
a dynamic positioned unit is in its final position
and all systems have been verified stable, or
a self-elevating unit has been jacked up to the
planned height.
)
4.1.1.3 A temporary safe condition can be considered
reached when the unit can sustain the .e nvironmentalloads
corresponding to the la-year seasonal condition, or the
characteristic environmental condition/loads
corresponding to 30 days exposure period, determined
according to PI. 1 Ch.3 Sec.2. Within 30 days the
positioning operation must be completed as pefined in
4.1.1.2.
4.1.1.4 When the positioning operation is completed, the
unit is regarded to be in a normal operating condition and
shall then comply with the relevant parts of its
Classification Rules, National Maritime Regulations, or
equivalenL See 1.1.1.4.
4.1.1.5 Positioning of offshore installation vessels (e.g.
crane vessels) covers the period needed for the activities
described in 4. J. J.1, and in addition also the subsequent
installalion operalions (e.g. lifting of modules).
4.1.1.6 For positioning of self-elevating units during
setting, reference is made to 4.5.
4.1.2.1 All positioning operations are normally
considered to be weather restricted, i.e. the operation
reference period is maximum 72 hours. See Pt. I Ch.2
Sec. 3. 1.2. This implies that the positioning operation must
be completed as defined in 4.1.1.2 or a lemporary safe
condition reached as defined in 4. J.1.3 within 72 hours.
4.1.3 Documentation
4.1.3.1 As part of planning for positioning operations
documents covering the following aspects shall be
prepared;
limiting environmental criteria for the positioning
operation
calculated characteristic loads on the unit and in
the positioning equipment
verification of acceptable strength of the unit and
the positioning equipment
4.1.3.2 In due time prior to a positioning operation the
following information shall, as relevant, be presented:
other surface or sub-sea operations going On in the
area
co-ordinates of ~e new location and planned
position and heading of the unit
waler depth, preferably chart showing deplh curves
with equidistance not exceeding 5 metres, LAT,
MWL and HAT and the slonn surge allhe
specified location
position of all floating andlor fixed structures
within 5 nautical miles off the specified location
position of obstructions on the seabed, wellheads,
etc.
position of pipelines and their protection (i.e.
buried, rockdumped or no protection)
full description of seabed lopography and soil
stratigraphy for prediclion of anticipated
penetration andlor anchor resistance. The
d~scription shaH contain information on rock
outcrops, pockmarks, iceplough marks, soil
classification properties and depth boundaries of
each soil layer
.
detailed chart(s) showing the exacl position of each
unit (including stand-off positions when
applicable), the position of each anchor, and l~e
calculated clearance
available experience from previous positioning
operations in the area
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.7 Transit and Positioning of Mobile Offshore Units
January 2000
Page 10 of 16
stability calculations with specification of
anticipated variable .loads to be onboard during
positioning
proposed pretonding procedure, including
minimum installation tension of drag-installed
anc~ors, as assumed in the anchor design
calculations
positioning procedure detailed plan for the
operation including data for the attending vessels,
number of positioning anchors to be used, etc.
for units using dynamic positioning equipment,
specificatio~ of the means and points of reference.
4.1.3.3 The limitations for characteristics design
parameters shall be evaluated and specified in the
operations manual.
4.2.3 Mooring systems
4.2.3.1 In general, the mooring system for floating units
shall comply with the requirements of DNV's "Rules for
Classification of Mobile Offshore Units", Pt.6-Ch.2., or
equivalent.
However. for mooring periods of maximum 72 hours it is
sufficient that the actual mooring arrangement complies
with PI. J Ch.2 Sec.S.3 for the characteristic environmental
condition for the operation.
4.2.3.2 For long-term or permanent mooring (e.g.
noaling production units) National governmental
regulations may also be applicable for the design of the
mooring system.
Limiting design p~ameters are to be given as a
combination of:
significant wave height, Hs
range of zero up-crossing periods. Tz
maximum 10 minutes mean wind all0 meters
elevation (if wind has significant influence)
maximum current at centre of maximum exposed
area (if current has significant influence).
4.2.3.3 The mooring system may in general be analysed
by quasistatic methods. For water depths of 200 meters or
more, dynamic analysis should be performed.
The operational criteria shall be less than the design
criteria, as specified in PI. 1 Ch.2 Sec.3.1.2.3.
4.2.3.4 During installation and normal operation of the
mooring system accurate monitoring of line lengths out of
the winch and .line tension is important for obtaining and
controlHng the planned condition. The floating unit shall
therefore have reliable equipment with sufficient accuracy
for continuous measurement and display of these
variables.
4.2 STATION-KEEPING SYSTEMS
Guidance Note
Methods for calculation and verification of the resistance of dragInstalled anchors are given In DNV's "Recommended Practice
RP-E301 . DesIgn and Ins lallation of fluke anchors in clay· and
DNV's ~Recommended Practice RP-E302 - Design and
Installation 01 dmg-In plate anchors In clay·.
4.2.1 ·General
4.2.1.1 Two types of station-keeping systems are
assumed in this chapter:
mooring systems with anchors. chain cable andlor
_steel wire rope or fibre rope anchor lines, with or
without thruster assistance
dynamic positioning systems.
4.2.2 Design requirements
4.2.2.1 The station-keeping system shall have acceptable
capacity, see 4.2.3 andlor 4.2.4, both for intact condition
(ULS) and one-line or one-component failure situations
(PLS).
4.2.2.2 The station-keeping system shall be designed,
with emphasis on flexibility and redundancy, to keep the
unit in position both in the sUrvival and the operating
condition, without overloading any component of the
system.
4.2.4 Dynamic Positioning (DP) systems
4'.2.4.1 For positioning operations close to another vessel
or offshore installation, the DP system of the unit shall
comply with the requirements of DNV's "Rules for
Classification of Mobile Offshore Units", Pt.6 Ch.7Dynamic Positioning Systems, class notation DYNPOS
AUTRO, or equivalent. Vessels with DP systeD)
complying with class notation DYNPOS AUTR
requirements or equivalent may be accepted after
consideration of procedures, equipment and consequences
of failures for the actu~l operation.
4.2.4.2 The capacity of the DP syste~ shall be
documented or tested to prove compliance in the
characteristic environmental conditions· with the motion
envelopes set for the actual operation. See also 2.2.1.1.
4.2.4.3 The complete DP system shall be function tested
with acceptable results before commencing the
positioning operation.
)
DET NORSKE VERITAS
()
Rules Cor Marine Operations
Pt.2 Ch.7 Transit and Positioning of Mobile Offshore Units
January 2000
Page 11 of 16
4.3.3 Clearance during positioning
4.3 CLEARANCE
4.3.1 General
4.3.1.1 The station-keeping system requirements referred
to in 4.2.3 and 4.2.4 contain few criteria for minimum
clearance between units, sub-sea structures, pipelines and
anchor lines. Specific clearance requirements for
positioning. short~tenn operations and normal operations
are therefore given in this section. The arrangement and
capacity of the station-keeping system shall sati,sty those
clearance requirements.
Table 4.1 gives a summary of the requirements for
minimum clearance given in this section between units,
pipelines/sub-sea structures and mooring elements during
positioning and during normal operation.
Guidance Note
.
The field operator (oil company) may specify more strict
requirements for clearance than given herein. Also, National
authorities may have other clearance requirements, In particular
tor floating production units.
4.3.1.2 Sufficient clearance shall be .e nsured at all times
between the unit and adjacent structures, between anchor
lines during cross anchoring and between anchor lines ~nd
fixed structures or other floating units. Environmental
conditions. motions and consequences of breakage of one
anchor line during the operation shall be considered in
order to establish sufficient clearance.
4.3.1.3 For wate,:- depths less than 60 meters, less severe
mooring line clearance requirements than given in this
section may be accepted, after thorough consideration of
anchoring arrangement and consequences of failures or
erroneous operations.
4.3.2 Clearance for synthetic fibre rope lines
4.3.2.1 The minimum clearance between anchor lines
and pipelines/structures given in this section are for chain
cabJe and steel wire rope anchor lines.
4.3.3.1 During positioning operations a minimum
clearance of20 meters between the actual unil and
adjacent fixed structures or other floating units shall be
maintained.
4.3.3.2 During positioning operations the minimum
clearance between the anchor lines of a unit and a fixed or
floating structure shall be as given in 4.3.5.3 for normal
operation. intact mooring system During installation of
crossing anchor lines from two or more units, contact
between the individual anchor lines is normally not
accepted. See also 4.3.5.2.
4.3.3.3 During positioning operations the minimum
clearance between the anchor lines/anchors of a unit and
pipelineS!sulr~ea structures shall be as given in 4.3.5.5 for
normal operation. intact mooring system.
4.3.4 Clearance during
short~term
operations
4.3.4.1 For short-term operations. e.g. lifting operations,
smaller clearance than required for normal operations (see
4.3.5) may be accepted, as detailed in 4.3.4.2 and 4.3.4.3.
4.3.4.2 During short-term operations {he dislance
between floating units or to a fixed structure is not to be
less than 3 meters at any point during transient motion
after breaking any one an~hor line or loss of anyone
thruster.
4.3.4.3 However, a smaller distance than required in
4.3.4.2 may be acceptable upon thorough consideration of
operational procedures, duration of the operation,
environmental conditions (in particular wind and wave
directil;m), considerations of back up systems such as
thrusters, rendering systems etc., and consequences of
accidental contact between the unit(s)/fixed structures.
4.3.5 Clearance in normal operation
For mooring systems using synthelic, fibre rope anchor
lines, the clearance will be assessed on a case-la-case
basis. The minimum clearance required will depend upon
the geometry of the mooring system during variation of
environmental loads and the consequences of contact
between anchor lines and pipelines/structures.
4.3.5.1 The distance between floating units in operation
or to a fixed structure is nolto be less than 10 meters at
any point during transient motion after breaking anyone
anchor lineor loss of anyone thruster.
4.3:2.2 Synthetic fibre rope lines shall never be in
contact with the seabed, neither during installation nor
during operation.
For a mobile offshore unit in drilling mode or moored close to a
fixed structure with gangway connection, the aclual operation
(e.g. drilJlng oraccommgdation) should nonnally be suspended
and the unit brought to a survival condition when the anchor line
lenslon reaches O.B times the tested anchor line tension.
Guidance Note
DET NORSKE VERITAS
•
Rules for Marine Operations
Pt.2 Ch.7 Transit and Positioning of Mobile Offshore Units
January 2000
Poge 12 of 16
4.3.5.2 In case of cross anchoring of two or more units
the documentation of the anchor pattern shall include
catenary plans for all anchor lines. The, anchor pattern and
the .tension in .the anchor lines shall be such .that a
clearance exists between individual lines in all intact
conditions, motion of units included. In one line broken
conditions, contact with steel wire anchor lines shall not
take place. while contact between chain cable anchor lines
is accepted.
4.3.5.3 For the intact mooring system, the following
minimum clearance shall normally be maintained between
the anchor lines of a unit and a fixed structure, motion of
unit included:
for "hot" structures (in opcrntion) the minimum
clearance shall be 10 meters in all directions
for "cold" structures (during installation, etc.) the
.minimum clearance shall be 5 meters in all
directions.
( )
4.3.5.4 10 the one line broken condition, the following
minimum clearance shall nonnally be maintained between
the anchor lines of a unit and a fixed structure:
for "hot" structures (in operation) there shall be no
contact
for "cold" structures (during installation, etc.)
contact may be accepted. based on a case-by-case
evaluation.
4.3.5.5 In case of interference between sub-sea
installations such as pipelines, templates, manifolds, etc,
and anchor lines, the anchor(s) and the anchor line(s) shall
be positioned such that an accepta~le clearance !!xists
between the anchor/anchor line and the installation in all
conditions. Anchor lines crossing sub-sea structures are
normally not accepted.
The following clearance shall normally be maintained;
)
vertical clearance between exposed pipeline and a
crossing anchor line shall not be less than 10
meters for the intact mooring system. motion of
unit included, arid positive in the one line broken
case
vertical clearance between buried pipelines and a
crossing anchor line shall be positive for the intact
mooring system, motion of unit included. i.e. the
anchor line shall no.t touch the seabed above the
pipeline, while contact is accepted in the one line
broken case
horizontal clearance between exposed pipeline or
sub-sea structure and a anchor line not crossing
shall no.t be less than 150 meters
horizontal clearance between buried pipeline and
an anchor line not crossing shaH not be Jess than 50
meters
horizontal clearance between anchor and a pipeline
shall not be less than:
150 meters in front of the pipeline, this distance
may however be reduced to 50 meters if the
installation of the anchor is monitored and
controlled by means of ROV
150 meters when the pipeline is parallel to the
anchor line
250 meters when the anchor line is crossing the
pipeline .
horizontal clearance between anchor and a sub-sea
structure or a fixed unit shall not be less than 300
meters. This distance may however be reduced to
50 meters in the anchor drag sector away from the
structure if the installation of the anchor is
moni.tored and controlled by means of ROV.
Guidance Note
Buoys may be !'lttached along the anchor lines during installation
and operation in order to ensure sufficient vertical clearance to
sub-sea structures and pipeilnes.
Guidance Note
The minimum anchor clearances to seabed structures given are
for drag-Installed anchors. For other anchor types without
slgnlftcant drag. less clearance may be accepted.
4.4 INSTALLATION OF ANCHORS
4.4.1 General
4.4.1.1 The anchor installation procedure shall in
particular address how sufficient clearance between
anchor Jines and sub-sea installations are achieved and
maintained during the installation operation. Criteria for
clearance between anchors and pipelines/sub-sea
structures nre given in 4.3.5.5.
4.4.1.2 Handling and transfer of anchors shall not take
place above unburied pipelines and sub-sea-installations.
Guida,nce Note
"Handilng and transfer of ancho~· in this connection means
anchors suspended over the stem or side of an anchor
0
Install~tIon vessel. •Above" m~ans Inside a sector of ± 20 from
the vertical through the pipeline/sub·sea Installation to the sea
surface. -
4.4.1.3 Contact, i.e. zero clearance, between anchor lines
and unburied pipelines during anchor handling is normally
not accept¢.
Guidance Note
Buried pfpelines may have limited protection against seabed
dragging ·of mooring chain. Sideways and longitudinal dragging of
mooring chain over buried pipelines should therefore not take
place during anchor Installation.
)
DETNORSKE VERITAS
()
Rules for Marine Operations
Pt.2 Ch.7 Transit and Positioning of Mobile Offshore Units
January 2000
Page 13 of 16
4.4.2 Drag-installed anchors
4.4.3 Other anchor types
4.4.2.1 Anchors shall be installed by an anchor-handling
4.4.3.1 This section covers installation of anchors usually
used for pennanent or long-term mooring of floating
structures, such as pile anchors, plate anchors, suction
anchors and gravity anchors.
tug of adequate size and ballard pull capacity.
4.4.2.2 For permanent or long-term moorings, the anchor
resistance after installation shall be verified as required by
National governmental regulations, or as given in DNV's
"Recommended Practice RP-E301 - pesign and
installation of fluke anchors in clay" or DNV's
"Recommended Practice RP-E302 - Design and
instaUation of drag-in plate anchors in"clay". as relevant.
4.4.2.3 For mooring periods less than 5 years where the
consequences of anchor dragging during the maximum
characteristic environmental condition is critical to
adjacent installations, human life or the environment, the
anchor resistance shall be verified by applying a mooring
test load of 1.25 times the maximum characteristic line
tension, intact mooring system. If this test load cannot be
obtained, the maximum anchor line tension under nonnal
operation must not exceed 0.8 times the anchor lest load
reached.
4.4.2.4 For mooring period~ less than 5 years where the
conseguences of anchor dragging during the maximu~
characteristic environmental condition is not critical, the
anchoTI:esistance shall be verified as given in 4.4.2.3, or
by applying a mooring .test load that previous experience
at the· location has prav.ed sufficient.
4.4.2.5 The resistance of pre-set, drag-installed anchors
planned to·he used several times should normally be
verified as given in DNV's "Recommended Practice RPE301 - Design and ins41llation of fluke anchors in clay" or
DNV's "Reconunended Practice RP-E302 - Design and
installation of dri'lg":in plate anchors in day", as relevant."
4.4.2.6 During testing of moorings the line tension for
chain cable shall not exceed the proof load of the chain,
but maximum 0.8 times the MBL of the chain. For steel
wire anchor )ine the mooring test load shall not exceed 0.5
times the MBL of the wire. The ten~ on shall be
maintained for at least 15 minutes without dr~gging of the
anchor to ensure that sufficient anchor resistance has been
reached.
.Table 4.2 contains ~ surnrnary of the requirements for
veritication of resistance of drag-installed anchors given
in this section.
.,
4.4.3.2 The anchors are to be installed within the
tolerances given in the design documentation.
4.4.3.3 The installation manual shall as a minimum
address:
transport of the anchors, including seafastening
installation tolerances, including position- and
vertical toleranc es
procedure for reversing the installation of any
anchor not installed within acceptable tolerances
procedure for tensioning and lay down of the
anchor Hoes after installation of lhe anchors
procedure for inspection of anchors and anchor
lines after installation.
4.5 POSmONING OF SELF-ELEVA TlNG UNITS
4.5.1 General
4.5.1.1 The structural strength, air gap and overturning
stabHity on the s.eabed of the self-elevating unit shall
comply with the requirements of DNV's "Rules for
Classification of Mobile Offshore Units", Pt.3 Ch.2 Sec.3
- Self-Elevating Units .. or equivalent.
Guidance Nole
Acceptable methods for design analysis can be found in DNV"s
·Classlfication Note No. 31.5 - Strength Analysis of Main
Structures of Self-Elevating Units·.
4.5.1.2 Liniiting environmental conditions (e.g. waves,
current, wind, motions etc.) shall be given in the
Operations Manual for the following conditions:
transit
installation and-retrieval
operation.
4.5.1.3 Anticipated penetration shall be calculated for the
nctuallocal.ian, based on available information on soil
characteristics and environmental conditions .
Guidance Note
Acceptable criteria for soil conditions and methods for analysis of
foundaUon behaviour can be found in DNV's ·Classification Note
No. 30.4 - Foundations· .
4.4.2.7 If sufficient resistance is not obtained with a
single anchor on a mooring line due to unexpected soil
conditions .on the location, "piggy back" anchor(s} may be
applied. Documentation of arrangement, strength and
operation procedure for installation and testing of "piggy
back" anchors are to be presented.
)
DET NORSKE VERITAS
Rules for Marine Operations
Pt.2 Ch.7 Transit and Positioning of Mobile Offshore Units
January 2000
Page 14 of 16
4.5.2 Clearance
4.5.2.1 Minimum horizontal clearance to floating-and
fixed units shall be determined for the positioning
operation, based on environmental conditions and motion
characteristics of the unites) involved.
4.5.2.2 During positioning the distance between the unit
and a "hot" fixed structure/platform (in operation!
production) shall normally be minimum 10 meters at any
point. If a closer position is required. the production shall
be closed down and the systems depressurised (Le. "cold"
condition).
4.5.2.3 The required minimum clearance to an adjac~nt
fixed structure/platform during operation (i.e. after
completion of the positioning operation) will be
considered in each casc. Regarding clearance to floating
units, see 4.3.5~
4.5.2.4 Sufficient air gap bi!lWeen the hull structure and
the design wave crest shall he ensured for the operating
position.
Guidance Note
The air gap is defined as the clear distance between the lower
part of the hull structure and the maximum wave crest elevation.
4.5.3 Seabed conditions
4.5.3.1 For general site assessment and evaluation of the.
foundation behaviour of ajack-up rig. adequate
geoteGhniGaI and geophysiGaI information shall be
availaple, including infonnation about:
elevating machinery
bilge, ballasl and prelo.ding syslem
anchoring equipment.
4.5.4.2 If lhe condilions allhe localion and lbe
anticipated penetration depth are such that erosion is
likely to occur around the spudcans, the possibility of
using bagging to avoid this situation shall be evaluated.
Guidance Note
If jetting is used to Increase the leg penetration depth, some
erosion may be accepted.
4.5.4.3 Prior to installing a self-elevating unit at any
location, the foundation behaviour of the unit during all
phases from installation to removal shall be thoroughly
. documented.
4.5.4.4 The penetration depths of the individual leg
foundations (spudcans) shall be calculated. Calculations
can be based on bearing capacity fonnula. A range for
possible penetration shall' be worked out. It shall be
checked that required hull air gap can be obtained when
maximum penetration of spud can occurs.
)'
4.5.4.5 If studies show that there is a risk for punchthrough failures. the hull clearance (air gap) shall be kept
as small as possible during pre-loading. Also the punchthrough distance shall be evaluated. It shall be
demonstrated that the jack-up can withstand such punchthrough displacements. The change in both overturning
moment and resisting moment due to increase in
penetration of one leg shall be taken into account.
4.5.5 Jacking operations
seafloor topography and sea bottom featlJres
soil stratification and classification
characteristics for soil in various strata
G_U ldance Note
4.5.5.1 Jacking operatiqns shall be performed within the
limitations given in the Operations Manual, see 4.1.3.3.
For .further recommendations regarding methods and extent of
soli investigations, reference Is made to DNV's ·Classification
Note No. 30.4 - Foundations·.
4.5.6 Testing
4.5.6.1 As a part of the installation procedure, the unit
shall be pre-loaded in such a manner that each leg is
subjected to aload equivalent to the maximum load
expected at the location.
4.5.3.2 The installalion area shall be free from
obstructions such as:
boulders
wrecks
lost construction material.
When entering a pre-used location, care shaH be Laken
during preloading to avoid that one leg hits an abandoned
leg-hole.
)
4.5.6.2 The maximum loads shall be detennined for the
most unfavourable combination of environmental and
functional loads in survival and operating conditions. Full
pre-load shall be maintained for minimum 1 hour after the
penetration has stopped.
4.5.4 Operational aspects
4.5.4.1 Prior to positioning operations of self-elevating
units the functioning of the following equipment shall in
particular be checked or tested and found in order:
DET NORSKE VERITAS
)
n
January 2000
Page IS of 16-
Rules for Marine Operations
Pt.2 Ch.7 Transit and Positioning of Mobile Offshore Units
-
Table 4 1 Minimum clearance
Anchor line
Units/structures and
mooring clements involved directions
()
Surface clearance
Floating and fixed units, or
two floating units
Fl.oaling and fixed units, or
two floating units, shortterm operations (e.g. SSCV
lifting)
Self-elevating unit and
fixed unit in operation
("hot" , in production)
Self-elevating unit and
fixed unit not in operation
("cold", not in produclion)
Sub-sea clearance
Anchor lines of a unit and
a platform in operation
("hot'\ in oroduction)
Anchor lines of a unit and
a platform not in operation
("cold", not in production)
Anchor lirie qnp an
unprotected pipeline
Anchor line and a
protected pipeline
Anchor line and a sub-sea
structure
Anchor line and a sub-sea
structure or an unprotected
pipeline
'Anchor line and a
protected pipeline
Anchor lines of two or
more floating units
Anchor and a pipeline
Anchor and a pipeline
Anchor and a pipeline
Anchor and a sub-sea
structure or fixed unit
During positioning
In normal operation!
nositionin completed
Vertical
Horizontal
Vertical
Horizontal
-
-
20m
-
b) 10m
-
-
b) 3 m,or
to be agreed
in each case
-
-
-
-
10m
-
To be agreed in
each case
-
-
To be agreed
in each case
-
To be agreed in
each case
.
Any
direction
a) 10m
a) 10m
a) 10m
b} No contact
a) 10m
b) No contact
Any
direction
a) Sm
a) Sm
a) Sm
b) Contact
acceoted
Crossing
pipeline
Crossing
pipeline
a) 10m
a) Sm
b) Conlact
accepted
a) 10m
b) No contact
a) No contact
b) Contact
accepted
-
-
No contact
-
Crossing
sub-sea
structure
Not crossing
(parallel 10)
-
-
Crossi~g
-
Crossing
normally nal
accepted
150m
-
normally not
accepted
150m
Not crossing
(parallel (0)Crossing
lines
-
Sam
-
Sam
No contact
-
a)No contact
b)Contact
between chain
lines accented
-
-
250m
-
250m
.-
150m
-
150m
-
150m
I)
arSOm
-
150m
I)
orSOm
"
Crossing
pipeline
Parallel to
pipeline
Not crossing,
not parallel
to pipeline
Any
direction
-
I)
[f ROV
control dunng mstallatton of anchor.
I)
If the anchor drag sector is away from the.structure.
-
300m
300m
I)l)
I)l)
ar50m
orSOm
..
.) Intact system, motion of umt mcluded, design
environmental loads
hI One line broken, transient motion.
DETNORSKE VERITAS
.
January 2000
Page 16 of 16
Rules for Marine Operations
Pl2 Ch.7 Transit and Positioning of Mobile Offshore Units
Table 4.2 ~ Verification of resistance 0 fd rUI!-lRsta II ed ane hors
Mooring category
1
Mooring period, P
Periodical survey interval
of anchor system as
Long-term or permanent
lnoorinl:
P>5 years
,
2
Mobile mooring
3
Short-term operation
72 hrs < P < 5 years
P<72hrs
Survey every 5 year
Normally no periodical
survey assumed in the design
required by National
governmental authorities
or the Class of the unit
Typical MOU involved
Theoretical verification
of anchor r.esistance
Production unit
As required by National
SSCV
As given in PI.! Ch.2
should be verified as given in DNV RP-E301" and DNV
RP-E302'I, or equivalent.
DNV RP-E302J},
Verification (testing) of
As required by National
anchor resistance as
governmental regulations,
as given in
installed on actual
Installation vessel,
governmental regulations. or MOU, PI.6 Ch.2 ", or
See.5.3.
as given in:
-"'IuivalenL
DNV Rules for MOU, PI.6
If the consequences of anchor dragging during the maximum
Ch.2 ",
characteristic environmental condition is critical for the
actual location and operation, the design anchor resistance
DNV RP-E301" and
or equivalent
location
Drilling unit,
accommodation uni~
installation vessel
As given in DNV Rules for
DNV RP-E301'1 and
DNV RP-E302'I,
or ~ approved in the anchor
design.
If the consequences of anchor draggiI!g during the maximum
characteristic environmental condition is critical, the anchor
resistance shall be verified by applying a mooring test load
of 1.25 times the maximum'charactet:istic line tension, intact
mooring system.
If this test load cannot be obtained, the mp.ximum anchor line
tension under nannal operation must not exceed 0.8 times
the anchor teslioad reached.
If the consequences of ancho~ dragging during extreme
environmental conditions are not critical, the a'ochor
resistance may be verified by applying a mooring test load
that previous experience at the location has proved sufficient.
Maximum lest load
Minimum time for final
test load
I)
"
Chain cable:
Steel wire:
Chain proof load, but max. 0.8 MBL
Max. 0:5 MBL
IS ·minutes
DNV's "Rules for Classification of Mobile Offshore Units", Pt.6 Ch.2 Sec.5.
'I DNV's "Recommended Practice RP-E301- Design and installation of fluke anchors in clay",_
3)
DNV's "Recommended Practice RP-E302 - Design and installation of drag-in plate anchors in clay".
DETNORSKE VERITAS
(