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Sandvik Chomutov Precision Tubes in the Czech Republic, a fully-owned subsidiary of AB Sandvik Steel in Sweden, is manufacturing long lengths of SAF 2507 super duplex tubing and winding them onto huge coils to be used for hydraulic umbilical tubing for subsea use primarily in the oil and gas industry. The long-coil technology was made possible by the application of orbital welding. Until recently, only single lengths of straight tubing were produced, or single lengths were wound onto much smaller coils. The ability of orbital welding to make consistent, uniform welds of high quality, weld-after-weld, was what made the long-coil technology practical. Extensive testing was done on the orbital welds before beginning production. The welds passed all the relevant code requirements and were found to have the balanced phase structure of duplex stainless steel essential for its favourable mechanical properties and excellent corrosion resistance. An Arc Machines Model 227 power supply with a cooling unit to cool the cables and weld head, and a Model 95-1500 weld head which has the capability of feeding wire into the weld, were installed on the production line with the weld head suspended from a cable so that the head is operating upside-down. Straight lengths of tubing are fed to the orbital welding station, where the weld is made and then passed to the X-ray station for examination while the next weld is in progress. This technology has many advantages which will reduce the costs and time required for installations. Reprinted from Welding Design and Fabrication, May 2001 Click here for full article... |
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