MECHANISATION AUTOMATION - Esab

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Increased qualityBy replacing old control boxes and power sources withthe latest models, during the retrofit, fabricators gain theability to store optimum welding parameters settings,benefit from improved start and stop characteristics, andobtain consistent weld positioning from joint trackingsystems. The result is improved weld quality and a userfriendlysystem.SAW flux dryers and heaters, in combination with anupgraded flux supply system, are another example. Bykeeping flux dry and hot, weld porosity from moistureis prevented and rejects avoided.Retrofit project provides Kvaerner with40% higher welding productivity.Kvaerner Kamfab AB, in Karlstad Sweden, a member ofthe Norwegian Aker Kvaerner Group, specialises in themanufacture of equipment for the chemical pulp industry;from single machines to complete production lines. Thecompany employs some 235 personnel and has a turnoverof around 400 MSEK.ESAB has a long relationship with Kvaerner Kamfab asa supplier of welding equipment and consumables. Overrecent years, ESAB has seen increasing demand fromKvaerner for new equipment and retrofitting of existinginstallations – mainly due to the overwhelming successof Kvaerner’s latest pulp washer, the Compact Press.This high efficiency, high capacity washer, developed byparent company Kvaerner Pulping AB, was introducedin 2000 and, since then, some 50 installations have beendelivered world-wide.With increasing orders and customer demand for shorterdelivery times, Kvaerner made further investment inmachinery, including the retrofitting, by ESAB, oftwo giant column and boom (CaB) installations for thewelding of cylindrical pressure tanks. The tanks, have adiameter of 3m and a length of 18m, and are submergedarc welded both from the inside and from the outside.The welding covers various qualities of stainless steelwith 10-15mm wall thickness. The objective was toincrease the capacity of the installations. The projectwas completed during 2003.Each CaB installation was stripped from its old weldingequipment. The remaining framework was reconditioned,painted and equipped with new welding heads, flux unit,power sources and cabling (see photo). New equipmentincluded:• LAF 1250 power source.• A6S welding head with motor slides and twinwire equipment.• PEH control box.• GMD joint tracking system.• Flux feeding and recovery system with TPCpressure tank.• General overhaul of the system, including newcable chains.Kvaerner calculations indicate that the retrofit has resultedin a 40% increase in productivity, mainly due to:• higher deposition rate due to changing over to twin arcwelding.• less post weld labour due to a n improved weld quality.• reduced downtime.Kvaerner Kamfab, last year, won their most prestigiousorder ever; a complete production line for the biggestpulp mill in China, located in Jian Lin and having acapacity of 3000 tons of pulp a day.About the authorsPeter Kjällström is After Sales Manager and Björn W.Ohlsson is Sales and Marketing Manager Automation atESAB Automation, Laxå, Sweden.For more information contact: peter.kjallstrom@esab.se22 • Svetsaren no. 1 • 2005
Mechanised welding of pipelinesBy: D.J. Widgery, ESAB Group LTD., United Kingdom.This article looks at the different approaches to mechanised pipeline welding and theirimplications in different parts of the world.Systems for the mechanised welding of pipelines havebeen available for more than 40 years and have long beenin exclusive use for offshore pipelines. Yet until recently,they were seen on only a few land pipelines. Now, however,the difficulty and expense of finding sufficiently skilledmanual and semi-automatic pipeline welders has led to arapid growth of mechanised welding onshore. This articlelooks at the different approaches to mechanised pipelinewelding and their implications in different parts of theworld.Early systemsAlmost as soon as CO 2-shielded welding was developed,torches were mounted on carriages for mechanisedcircumferential welding of pipelines. The first crosscountrypipeline to be welded semi-automatically with the CO 2process was laid in the US in 1961, when there were alreadyfive mechanised GMAW systems under development [1],with the first field trial taking place in the same year.Inevitably, Darwinian natural selection took its toll onthe early machines, but it is remarkable how soon thedistinctive features of today’s systems began to crystallise.Development started to diverge along two lines. In one,the welding heads or “bugs” were mounted on bands orchains clamped to the pipe. This became the model forsubsequent onshore systems. The other approach usedan external frame, inside which the welding heads weremounted, and this subsequently found its main applicationon lay barges. Designed for the wide, open spaces of theUSA and USSR, the first machines produced in the 1960sdid not have lightness or compactness as a priority andit is perhaps not surprising that they were not adopted incountries with narrower rights of way and more crossings.1. Drive motor2. Welding wire spool3. Welding head4. Chain5. Guide roll6. Wire feeder7. Wire feederIt was soon discovered that for semi-automatic welding,choosing the right size and type of consumable was thekey to success. There was an initial assumption that thesmaller the wire diameter, the more controllable the arcwould be, and a number of users tried 0.8 mm diameterwires. However, in side-by side tests, welders preferreda 0.9 mm type. It appeared that the lower electricalresistance in the electrode extension (stickout), and hencelower resistive heating, meant that wire burnt off moreslowly at a given current and more heat was availableFigure 1. Tandem mechanised pipe welding system byFalkewitsch, 1961 [1].to melt the parent material and avoid the dreaded “coldlaps” or lack of fusion. Another discovery was that theinclusion of a small amount of titanium in the wirereduced the burn-off rate further and again increased thewelder’s comfort and reduced the defect rate. Comparinga 0.8 mm titanium-free wire with a 0.9 mm titanium-containing one at 200A, 25V it was found that the respec-Svetsaren no. 1 • 2005 • 23
Page 1 and 2: THE ESAB WELDING AND CUTTING JOURNA
Page 3 and 4: Orbital-TIG - a great wayto join pi
Page 5 and 6: joint volume is reduced by a factor
Page 7 and 8: Light mechanisation.Easy and cost-e
Page 9 and 10: Figure 4. Manufacturing of stainles
Page 11 and 12: Railtrac flexible tool for Dutchpip
Page 13 and 14: Submerged arc welding of steelsfor
Page 15 and 16: onshore wind towers, whereas the to
Page 17 and 18: Results of mechanical testingThe we
Page 19 and 20: Figure 1. Welding tool with seam tr
Page 21: Retrofitting of automaticwelding Sy
Page 25 and 26: such as that from a rutile flux-cor
Page 27 and 28: Cutting technology in shipbuildingB
Page 29 and 30: Status of plasma cutting.In the que
Page 31 and 32: Improved productivityin automated a
Page 33 and 34: A CENTURY OF INNOVATION16-pound (7
Page 35 and 36: NOMAD finalisedFigure 1. The bridge
Page 37 and 38: OrigoMag C150/C170/C200/C250A recen
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