Effect of Partial Welding on the Residual Stress and Structural Integrity of Piping Welds

When weld defects are observed during an inspection after welding, repair welding is performed after removing the defects. However, partial repair welding can potentially complicate the weld residual stress distribution. In this study, we performed thermal-elastic-plastic analyses to evaluate the weld residual stress produced by repair welding after pipe butt-welding. The analysis results were validated through comparison with actual measurements. In addition, based on the analysis results for varying repair-welding conditions, we also performed structural integrity assessments related to stress corrosion cracking using the probabilistic fracture mechanics analysis code PASCAL-SP. It was clearly observed that the tensile stress in the repair-welded region increased and that compressive stresses occurred outside the repair-welded region. A deeper mechanical cutting depth caused larger increases in the tensile residual stress of the repair-welded region. It was also concluded that partial repair welding may favorably affect the break probability of piping welds.