Mitigation of the residual stress and deformation in seam pipe with girth welding and cutting

Abstract

Seam pipes are widely used in marine plant equipment due to their ease of fabrication and cost-effectiveness. However, localized heating and cooling occur during the welding and cutting processes in the process of pipe fabrication, which may lead to the redistribution of residual stresses and cause excessive deformation.Uncontrolled residual stress and deformation can cause geometric intolerance during spool assembly, leading to significant economic losses. Therefore, it is necessary to understand the characteristics of residual stresses caused by welding and cutting in piping.This study investigates the redistribution of residual stress in seam pipes during manufacturing, cutting, and girth welding using both finite element analysis and experimental validation. A thermo-mechanical analysis was conducted using MSC Marc, and residual stress was measured at each stage using the hole-drilling method to verify the numerical results. The findings from this study showed that the residual stress at the point opposite the seam weld changes from tensile to compressive after cutting and rewelding. The results of this study provide a technique for reducing the conservatism in engineering critical assessments using relieved secondary stresses.