IIW White Paper

nature and not specifically related to the oil and petrochemicals environment. It is therefore important for bodies like IIW to provide the assurance that refining and petrochemicals companies can look toward for guidance on appropriate training, qualification and certification for their personnel. International Bodies such as the IIW, therefore, do have an important role to play in assisting industries to ensure that the standard of training providers is up to international requirements, that training syllabi are reviewed periodically to reflect advances in the science and technology of welding and that it has relevance to the refining and petrochemical environment. There is also the need to provide training to a wider spectrumof the refining and petrochemical operations such as the plant technologists, process technologists and operations personnel as well, and not just targeting the training effort on personnel that have the direct functional roles and responsibilities on welding related matters e.g. welding engineers, specialists, practitioners. In addition, supporting service organisations such as pressure equipment fabricators would also need to be given assistance to be updated on handling of new material, fabrication techniques, welding processes, etc. The offshore oil and gas industry is moving into deeper waters. Several issues arise: The pipe wall thickness needs to be increased to resist hydrostatic collapse. The pipelines may have to be laid by J-lay, instead of the more conventional S-lay method to reduce the weight supported by the lay barge. The hydrocarbons are higher pressure and temperature and often containing a higher concentration of acid gases making the fluids more corrosive. In J-lay it is generally only possible to have a single welding station. Presently automatic gas welding is used but this has limitations. Possible welding techniques for thicker wall pipe and alternative materials to carbon manganese steels include friction welding, flash butt welding, homopolar welding and friction stir welding. Stolt Comex Seaway is developing friction welding for pipeline and risers of 150-320 mm diameter. The weld is effected by rotating a profiled ring between two static pieces of pipe and radially compressing the rings so that it is welded onto both pipe sections simultaneously. It has been found that sound welds are possible in carbon manganese steels and also in the 13% super-martensite steels (cheaper but less weldable by fusion welding than the super-duplex steels). The welds can be made in about 15 seconds and the ring allows the possibility of introducing a non-matching material if the joint properties require it. Flash-butt welding (FBW) has been known for many years and is routinely used for welding chain and railroad rails, high-stress applications where quality welds are essential. The pipeline application was developed by the E.O. Paton Institute in Kiev, and was applied to some 30,000 km of large-diameter pipelines in the FSU. McDermott invested substantial resources (reportedly some $10m) in the development of FBW for offshore pipelines and piles, and produced some extremely positive publications, concluding that “on 36- inch pipe, flash butt welding is expected to be 50% more productive than semi-automatic GMAW welding. Conservative estimates for this size pipe indicate that production rates as great as 400 joints per day are possible in the double-joint mode….”. There have been some quality problems with the welds however, and work is continuing in this area through a special group established through a resolution at the IIW International Congress on pipelines in Sofia, Bulgaria in October 2010. This group is making good progress. Homopolar welding has some similarities with FBW. It butts the pipe ends together and connects a homopolar generator (Faraday disc) across them. The kinetic energy of the generator is suddenly converted into an intense pulse of electrical energy, typically 10 MW, for a few seconds. Resistance at the butt converts the energy into heat. The heated ends are then pushed together. 9.3.1 Offshore and onshore – Oil and gas

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