WELLDAC® HIGH-OUTPUTT D-STATE SOLID WELD DERS Proccesss set--up in nform matio on for yyour Weld dac ssyste em ocess Guide, G , for op peratorrs Weldac Pro Document 0 00311718 | Revv. B | 12 Januarry 2021 | 1 INTRODUCTION Whether you are an experienced or new operator of a high-frequency welding equipment, EFD Induction would always recommend that you take some time to familiarise yourself with the controls and set-up of your new equipment. In this document we will concentrate on the weld area and the components that are critical to ensuring efficient operation of your new Weldac and your process in general. The guide is valid for carbon steel products. In case of stainless steel or other materials, please contact us for guidance. 1. The subjects covered are: 2. Induction coils and contacts 3. Impeders and cooling 4. Strip edge presentation and vee 5. Welding parameters 6. OD weld bead removal 1.1 Checkpoints For quality welding with high efficiency, check the following set-up and conditions: Correctly slit steel strip: width, straightness, flatness and burr. • • • • Correctly shaped open tube: parallel edges and no edge offset in the welding zone. Induction coil position: approximately one coil length from the weld point. Impeder position: The ferrite should reach as close as possible to the weld point and one tube thickness below the vee. Ferrite length minimum: 2.5 x vee length. Impeder cooling liquid delivery pressure and temperature: Through flow – minimum 3 bar (45 PSI). Return flow – 5 to 8 bar (70 to 110 PSI). Coolant temperature as low as possible, inlet < 25 °C (77 °F). • • • • Vee angle: typical 2° to 4.5° for carbon steel. Other materials like stainless will demand different set-up. In case of two-turn induction coil, the first winding should cross over the vee. Correctly calibrated rolls: slight pull between forming and calibration sections. Uniform and constant speed. Document 00311718 | Rev. B | 12 January 2021 Page 1 www.efd-induction.com 2 PRACTICAL SUGGESTIONS FOR EFFICIENT WELDING 2.1 Constant Light in Welding Area There should be good and constant light in the welding area to avoid variations in the colour (brightness) of the vee and the external bead between day and night shifts. If the lighting is not constant, the operators may be led to believe that they see a colder weld temperature during daylight hours and adjust the power accordingly. 2.2 Weld with as High a Speed as Possible A high welding speed always provides a narrower heated zone of the strip, as less time is available to conduct the heat away from the strip. Further, there is less time for oxides to form in the ‘molten’ surfaces of the strip edges. 2.3 Coil Adjustment During Welding During welding and running-in new tube dimensions, it is necessary to adjust the induction coil position, especially for the weld-point-to-coil distance. An adjustable support table is advantageous and pays for itself by providing more efficient and better quality welding. The support table should be adjustable in one axis for two-turn induction coils, or adjustable in three axes for single-turn induction coils. 2.4 Temperature Monitoring We are of the opinion that automatic infrared temperature control with optical temperature measurement of the weld point is not sufficiently reliable. There is too much smoke and vapour that can make it challenging to get accurate control of power. For monitoring purposes however, it will assist the operator and can be used for trending documentation. 2.5 Strip Burr The direction in which the slitting edge burr is turned when the strip is fed into the welding line is important to both the size of the internal weld upset and roller wear. When cutting the strip to size, the knives in the cutting process make a small edge (burr) which is normally not trimmed off. Upward facing burr edge will be far worse for welding result. This is often leading to excessive melted material bonding to the impeder and quality issues (oxides) in the weld. Weld point will be interfered by to early shortening of the vee. Document 00311718 | Rev. B | 12 January 2021 Page 2 www.efd-induction.com 3 INDUCTION WELDING COILS Depending on the specific EFD Induction Weldac that you have purchased, you will normally use either two-turn coils, or single-turn coils. Typically, tube mills up to around 5-6” (127-152 mm) diameter will be equipped with a Weldac using two-turn coils whilst large mills, or especially heavy wall applications, will use single-turn coils. 3.1 Two-Turn Induction Coils Two-turn tubular coil with PTFE insulation and flange mount connection (mill direction dependant) Two-turn banded type induction coil with flange mount connection (bi-directional) 3.1.1 Induction Coil Cooling Cooling of the induction coil is very important as there are high currents flowing in the surface during operation. It is advisable to have a dedicated pump with a minimum delivery pressure of 3-4 bar for the coil. More information on minimum flow rates can be seen in the coil sizing table. Document 00311718 | Rev. B | 12 January 2021 Page 3 www.efd-induction.com 3.2 Two-Turn Induction Coil Selection Chart The table below is a selection guide for the standard range of Weldac two-turn coils. It tells you which coils to choose for standard tube and pipe sizes based on common industry standard norms. These guidelines were calculated with a consideration for practical clearance and electrical efficiency. Two-Turn Coils Standard welded tube OD Induction coil ID (mm) 10–11 12.7/13.0 14 15–16 17/17.3 17,86/18 19,05–20 21,3–22,23 25,4–27 28,58 30–32 33–35 38,1–41,28 42–45 47–50,8 53,5–57,15 60–65 70–76,2 80–88,9 101,6 108–114,3 120–127 133–139,7 141,3–152,4 159–168,3 177,8 193,7–203,2 (inch) 0,39–0,43 0.500/0.512 0,55 0,59–0,63 0.669/0.681 0.703/0.709 0,75–79 0,83–0,875 1–1,063 1,125 1,181–1,26 1,32–1,5 1,5–1,625 1.65–1.75 1,85–2 2,1–2,25 2,36–2,56 2,75–3 3,15–3,5 4 4,25–4,5 4,72–5 5,236–5,5 5,563–6 6,26–6,625 7 7,62–8 (mm) 16 18 20 22 24 26 28 31 36 39 43 46 51 56 63 70 78 93 106 120 135 148 162 176 194 205 234 (inch) 0,63 0,71 0,79 0,87 0,94 1,02 1,10 1,22 1,42 1,54 1,69 1,81 2,01 2,20 2,48 2,76 3,07 3,66 4,17 4,72 5,31 5,83 6,38 6,93 7,64 8,07 9,21 219,1 8,625 252 9,92 Water cooling flow requirement (l/min) (gpm) 17 4,5 17 4,5 17 4,5 17 4,5 17 4,5 17 4,5 17 4,5 34 9,0 34 9,0 34 9,0 34 9,0 34 9,0 34 9,0 34 9,0 34 9,0 34 9,0 34 9,0 34 9,0 34 9,0 34 9,0 34 9,0 34 9,0 34 9,0 34 9,0 34 9,0 34 9,0 34 9,0 34 9,0 Coil type Tubular Tubular Tubular Tubular Tubular Tubular Tubular Banded Banded Banded Banded Banded Banded Banded Banded Banded Banded Banded Banded Banded Banded Banded Banded Banded Banded Banded Banded Banded For tubular induction coils, the internal diameter (ID) shown is the actual active copper tube ID. On top, there is PTFE insulation, which means that the actual coil ID is 2 mm smaller. For example: The actual ID of an 18 mm coil is 16 mm. Document 00311718 | Rev. B | 12 January 2021 Page 4 www.efd-induction.com 3.3 Single-turn induction coils for large diameters Large diameter single-turn coils are normally sized on a case by case basis due to variations in pipe mill design, forming technology, customer specific needs, etc. The coils can be made with an offset and with a split connection at the bottom that is bolted or clamped. The coils are available in a laminated version or with cooling tubes externally brazed on. The benefit of the laminated coils is that they are easier to keep clean on the outside and lighter to handle. Both types of coils can be delivered with through-flow or closed-loop cooling configuration. Single-turn induction coil with offset and bolted flange connection and laminated through-flow cooling. Single-turn induction coil with through-flow cooling by brazed on cooling tubes. Document 00311718 | Rev. B | 12 January 2021 Page 5 www.efd-induction.com 3.4 Single-Turn Induction coil Selection Guide The table below is a selection guide for single-turn coils. These guidelines were calculated with a consideration for practical clearance and electrical efficiency. Single-turn coils will normally be adapted to the actual outside diameter (OD) size and need for offset due to weld roll configuration. Single-Turn Coils: Cooling water requirement up to 1000 kW Welded tube OD (mm) 88,9–101,6 114,3–127 139,7–152,4 159–168,3 177,8–203 205–215 219,1–229 244,5–273,1 279,4–304,8 323,9–355,6 382–406,4 419–457,2 473,1–508 530–559 572–610 635–660 (inch) 3,5–4,0 4,5–5 5,5–6 6,5–7 7,5–8,25 8,3–8,5 8,625–9 9,625–10,75 11,0–12,0 12,75–14 14,5–16 16,5–18 18,625–20 20,5–22 22,5–24 24,5–26 Induction coil ID Flow requirement (mm) (inch) (l/min) (gpm) 120 154 177 215 235 255 263 315 348 405 462 519 577 634 691 748 4,7 6,1 7,0 8,5 9,3 10,0 10,4 12,4 13,7 15,9 18,2 20,4 22,7 25,0 27,2 29,4 17 17 18 19 20 21 21 21 21 21 21 21 21 21 21 21 4,5 4,5 4,8 5,0 5,3 5,5 5,5 5,5 5,5 5,5 5,5 5,5 5,5 5,5 5,5 5,5 This chart is a guide only and is based on typical tube OD sizes. • • • • Sizing for all single-turn induction coils are evaluated and calculated based on the specific mill in question. Induction coil sizes should be adapted to main production tube OD sizes. Water cooling requirement will depend on the actual welder power. Induction coil sizes may also be adapted to main production sizes. Induction welding of large pipes. Document 00311718 | Rev. B | 12 January 2021 Induction coil with offset for easy access. Page 6 www.efd-induction.com 3.5 • • • 4 Guidance for Every Induction Coil Change Make sure to clean electrical contact area, both on the coil adapter and the busbar surface. − Use abrasive pads to remove oxides and contamination. Check Teflon insulation: If it is damaged, change it. Use the correct torque when mounting the coil. − Two-turn coil connection: 35 – 40 Nm. − One-turn coil connection: Minimum from 13 – 18 Nm depending on the width of the busnose, check the label on busbar coil clamp. CONTACT WELDING Although the general preference today is to use induction welding, some applications still use contact welding. These include special profiles and very large diameter pipes. The contact system will be delivered with a single or double contact shoe system. The contact shoes and contact tip material will be designed case by case. This is also valid for the replacement supply of contact shoes and the specific shape contact tips. Various types of contact tip materials are available. Please use the EFD Induction reference number for replacement. Contact shoes and contact tip. Contact welding with constant pressure from pneumatic cylinders. Shoes with ready brazed contact or loose contact tips in various materials are available as consumables. Brazing procedure for replacing the contact tip will be submitted with the delivery of a contact welding system. A separate brazing procedure for contact tips is included in the Weldac manual. Document 00311718 | Rev. B | 12 January 2021 Page 7 www.efd-induction.com 5 IMPEDERS The impeder is a ferrite core housed in a cover or case, usually a composite tube such as epoxy glass. The casing protects the ferrite core and directs coolant around or through the ferrite to ensure stable and correct operation. The basic function of the impeder is to concentrate the welding energy in the strip edges, thus reducing general heating of the pipe surface (wasted energy). For ferrous materials it is virtually impossible to weld without an impeder. Without impeder Current returns on the inside of the tube. With impeder Current flow along the edges of “vee”. The selection of the impeder is a critical factor in achieving high-quality weld integrity as well as satisfactory welding speeds and power consumption. Ferrite core grade, cooling distribution, diameter, length and fixing of impeders are all extremely important factors that should not be overlooked. Many publications stress the importance of positioning the impeder with the end of the ferrite just past the centreline of the welding rolls, but we know from experience that this is rarely practiced. This placement maximises electrical efficiency, but also reduces the life of the impeder due to burning of the casing. When running continuously, positioning the end of the impeder a little back from the welding point is probably better. However, it is important to understand that doing so will lead to increased induction heating of any metallic parts that may be part of the end of the impeder assembly. As pipe diameters get increasingly larger, the impeder ferrite may not fill the complete inside area of the pipe ID, in which case it is beneficial to position the impeder towards the top of the pipe. Document 00311718 | Rev. B | 12 January 2021 Page 8 www.efd-induction.com Weld set-up with coil and impeder position. Ferrite length is very important, particularly when the welding roll diameter is excessive or as tube diameters get larger. Probably the most common reason for excessive welding power consumption is insufficient ferrite length within the impeder. The length of the ferrite is calculated by multiplying the vee length x 2.5. Impeder cooling is critical and, if possible, coolant temperature should be kept below 25 °C, as increases above this temperature will require much more flow to achieve the same level of cooling. With small impeders, it can be beneficial to use a chiller to retain the inlet temperature at around 5-10 °C. Impeder sizing is a balance of electrical efficiency and practical clearance inside the welded pipe. As a rule, we recommend a clearance of around 20-25 % of the internal diameter between the pipe and the impeder. With smaller pipes it is better to use as much ferrite mass as possible. When sizing impeders you should take into account that the pipe dimension, we refer to is the finished diameter after sizing/calibration. The true diameter at the welding rolls will be slightly bigger, which may allow more clearance for the impeder. Impeders are available in a variety of types, shapes, configurations, diameters and lengths. The main types are: • • • • • Through flow – for general production Return flow – where reduced coolant inside the pipe is important ID scarfing – where special impeders form parts of a complete system Clusters/manifolds – for larger diameters (> 6”/152 mm) Square/rectangular – for direct linear forming profile mills Please, see the EHE Consumables catalogue supplied with your Weldac system for more information. Document 00311718 | Rev. B | 12 January 2021 Page 9 www.efd-induction.com 6 S STRIP EDGE PRESENTA ATION AN ND VEE ANGLE A The qua ality of strip edge prese entation can n greatly afffect the weld quality, thhe power consum mption and, ultimately, the t product ion speed. The best re esult is obtaained when the strip edges a are parallel, because th he heating p pattern betw ween the ins side and ouutside edges s will be even, due to the prroximity effe ect. pipe mills wiill typically present p edg ges that are slightly pea aked which will result in a Some p greater proximity effect e at the inside wall and increas sed heating g at the peaak. The operrator is then forrced to incre ease the po ower to achiieve a satisfactory weld d temperatuure on the outside o edges. T The result is an oversiz zed, ugly w weld bead in nside the pip pe. In additi on, tool life will be reduced d whilst ID scarfing. s Pea aked edges result r in unev ven heating. Parallel edges give even n heating botth inside and d out. The vee e angle is th he converge ence of the strip edges s at the weld d rolls; this iis just after passing through h the induction coil whe ere high freq quency currrent is applied. The anggle is imporrtant as it will de etermine ho ow much heating takes place on th he strip edges. Due to tthe proximity effect, a narrow an ngle will hav ve a more ra apid heating g rate as the e strip edgees are close er together. For carbo on steel pipes the angle e will typica ally be 2.5°-4.5°. Anglees below 2.5° can lead to pre-arcing and a flashov vers across the vee, wh hich is an in nterruption i n welding power. p The ang gle is determ mined by the forming p process in th he mill and the seam gguide roll/fin n which is the la ast roll beforre the induc ction coil. Fo or non-ferro ous materials, a vee anngle of 5°-7°° is recomm mended to avoid a excess sive oxidess forming in the molten surface of tthe strip edges. This can n lead to prroblems “squeezing” th hem out of th he bond pla ane and ressult in weld defects. d Ve ee-angle by b measurring Vee opening o at a distance from the weldpoiint Distance from oint, Vee weldpo length h (mm) 2 3 50 5 1 100 1 150 1,7 3,5 5,2 2,6 5,2 7,9 Document 00311718 | Re ev. B | 12 Janua ary 2021 e-angle (°) Vee 4 5 Vee op pening (mm m) 3,5 4,4 7,0 8,7 1 10,5 13,1 Page 10 6 7 5,,2 10 0,5 15 5,8 6,1 1 12,3 1 18,4 www.efd-induction.c com 7 WELDING VEE LENGTH AND ANGLE Weld set-up with important measurements to determine the weld efficiency Vee length is very important in the process because it will determine how much heating time is applied to the strip edges. The longer the vee length, the more heating of material will take place. The vee length is the distance from the weld roll centreline to the front edge of the induction coil. In an ideal electrical efficiency condition, the vee length should equal the length of the induction coil. This is often not possible to achieve because as the pipe diameter decreases, the welding roll size will influence how close the induction coil can be positioned. With small sizes, it is critical that the vee length should not exceed 4 x pipe OD. This is because excessive material will be heated up and cause so-called “blueing” (discolouration) of the pipe surface. It will also lead to difficulties with straightness where the pipe exits the mill. 8 WELDING PARAMETERS Your new Weldac includes a Weld process Assistance System (WAS). This is a recipe storage system for collecting data on power settings and dynamic running parameters from the welder. Document 00311718 | Rev. B | 12 January 2021 Page 11 www.efd-induction.com Main n Screen Recipe scre reen The WA AS is an exccellent tool for f achievin ng repeatab ble productio on paramete ters and setttings. It allows yyou to set parameter upper/lower limits which h will genera ate a qualityy warning iff they are exce eeded. The e parameterrs are outpu ut power, fre equency, AC C current annd welding speed. Pro ocess values s screen WAS screeen For full information n on the WA AS system, p please refer to the rele evant sectioon in the We eldac operatio on manual. Collect more set-u up data The tab ble on the la ast page which can be used for ma anually reco ording weld ing parame eters and more set-up da ata for the mill. m ble will guide e you on the e important factors for a successfu ul welding rresult. The tab 9 F FILTER AND A PUM MP COO OLING SY YSTEMS It can be e beneficiall for the coo oling supplyy to the coil and impede er to be booosted by a pump p equippe ed with a filtter to remov ve metallic p particles fro om the mill emulsion. e T This ensures s that no magnettic items can n become stuck s inside the impede er assembly y where theey will restric ct e heated by y the inductiion field, wh hich can lea ad to premaature failure of the coolant flow and be part. Document 00311718 | Re ev. B | 12 Janua ary 2021 Page 12 www.efd-induction.c com For thro ough-flow im mpeders, 3 bar is norm mally enough h pressure for f cooling, whilst returrn-flow impeders will requiire 5-8 bar to t overcome e the smalle er cooling channels an d ensure su ufficient flow ove er the inside e surface off the impede er casing. Typical combined pump p and filtter systems. These are available a in va arious modeels depending g on the pipe size a and flow requirements. 10 O OD WEL LD BEAD D REMOV VAL The high frequen ncy welding process produces an ““upset” or weld w bead on the insid de and outside of the pipe wall. Thhis is the ma aterial that is s squeezed out of the molten m strip edges at thhe welding rolls. Differrent cutting geometries s insert exam mples. The outtside weldin ng bead mus st always b e removed.. The standard processs is to use a hard metal (ccarbide) insert to remov ve this while e the materrial is still att a high tem mperature. This T is achieve ed with a too ol holder an nd a carbide e insert whic ch is positio oned just aftter the weld ding rolls. Th he size of th he carbide in nserts and tthe radius shape s is relative to the pipe diame eter, thicknesss, materiall specificatio on and line speed. For mo ore details on o the full range of im mpeders, coils, c filter & pumps aand OD & ID D scarfing g, please refer r to the EHE Cons sumables product p cattalogue su pplied with h your Weldac c system. Weldac c service su upport: If you y need im mmediate as ssistance, please p call our 24-hour service hotline: +47 97 70 99 99 (GMT + +1) Document 00311718 | Re ev. B | 12 Janua ary 2021 Page 13 www.efd-induction.c com Welding Process Data Collection: Document 00311718 | Rev. B | 12 January 2021 Page 14 www.efd-induction.com
