A Study on the Residual Stress of Seam Pipe Cutting and Girth Welding

Abstract

Seam pipes are easier to manufacture and cheaper than seamless pipes, and are widely used in the manufacture of pipe spools for marine plant facilities. The manufacturing and assembly of seam pipes involve welding and cutting. The localized heating and cooling that occur during these processes may change the existing residual stress and cause deformation. Uncontrolled deformation can accumulate as assembly errors at the next step, potentially delaying the entire process and causing economic losses. Therefore, characteristics of residual stress redistribution caused by cutting and girth welding of seam pipes need to be studied further. In this study, we performed thermo-mechanical analysis of the manufacturing, cutting, and girth welding processes of seam pipes using the commercial finite element analysis (FEA) software MSC Marc and analyzed the characteristics of residual stress. Furthermore, we measured the residual stress in each process using the hole drilling method, analyzed the characteristics of redistributed residual stress, and ensured reliability. Based on the results of FEA and measured residual stress redistribution, we can provide a basis for reasonable mitigation when performing structural integrity evaluation if there is a defect in the weld of the pipe.