Fatigue Behaviour of Skelp End Welds in Spiral Welded Oil and Gas Pipes

石油和天然气行业在加拿大经济中扮演着至关重要的角色。管道运营商使用地埋钢管作为输送石油、天然气和各种石油产品的主要方式。制造这些管道使用钢带进行变形和焊接，使用两种不同的焊缝：直缝焊和螺旋缝焊。与直缝焊管相比，螺旋缝焊管具有许多技术优势和经济效益。然而，螺旋缝焊管的制造过程需要多卷钢带送料。两个连续带的两端焊接在一起，然后将它们送入成型机，因此，在两个连续线圈的两端连接的地方形成一个骨架端焊缝（SEW）。虽然螺旋焊管现在被广泛认为是一种比直缝焊管更便宜、更好的建筑和替代管道，但螺旋焊管中含有SEW的部分被丢弃了。这是因为管道运营商对使用它没有信心，因为SEW管段的疲劳行为尚不清楚。这种种植过程导致加拿大管材厂的产量损失1%至5%，使其在全球市场上的竞争力下降。因此，本研究项目旨在确定在主要由操作压力波动引起的疲劳载荷下，螺旋焊接和SEW对现场管道结构完整性和安全性的影响。这项研究的结果将为螺旋焊管的结构完整性提供见解，最终可以被管道运营商和工程咨询公司转移和使用。因此，加拿大的管道制造工厂和管道运营商，以及加拿大的整体经济，预计将从这个研究项目中受益。特别是，Evraz和里贾纳的当地经济将从这项研究中受益，因为仅在里贾纳的Evraz生产设施就雇用了500名员工。这项研究的完成将需要对36英寸（915毫米）直螺旋焊管和缝螺旋焊管进行大量的全尺寸疲劳试验，无论是否使用SEW。

The oil and gas industry plays a critical role for the Canadian economy. Pipeline operators use buried steel pipelines as the primary mode for transporting oil, gas, and various petroleum products. Manufacturing these pipes uses steel strips which are deformed and welded using two different seam welds: straight seam weld and spiral seam weld. Spiral seam welded pipe offers many technical advantages and economic benefits as compared to straight seam welded pipe. However, the manufacturing process of spiral seam welded pipe requires feeding multiple coils of steel strip. The ends of two consecutive strips are welded together before feeding them into the forming machine and as result, a skelp end weld (SEW) forms where ends of two successive coils are joined. Though spiral welded pipe is now well accepted as a cheaper and better alternative to straight seam welded pipe for construction and replacement pipelines, the portion of the spiral welded pipe that contains the SEW is discarded. This is because the pipeline operators are not confident in using it as the fatigue behaviour of SEW pipe section is not known. This cropping process results in a yield loss of 1% to 5% for the Canadian pipe mills making them less competitive in the global market. Hence, this research project is aimed at determining the effect of spiral weld and SEW on the structural integrity and safety of a field pipeline under fatigue loads develop primarily from the fluctuations in the operating pressure. The results of this study will provide an insight in the structural integrity of spiral welded pipes which can ultimately be transferred and used by the pipeline operators and engineering consulting companies. Therefore, Canadian pipe manufacturing mills and pipeline operators, as well as the Canadian economy in general, are expected to benefit from this research project. In particular, Evraz and the local economy of Regina will benefit from this research, since Evraz's production facilities in Regina alone employ 500 people. Completion of this study will require a large number of full-scale fatigue tests on 36 inch (915 mm) straight and seam spiral welded pipes with and without SEW.