When weld defects are found by inspection after welding, repair welding after removing the defects is performed. The partial repair welding has a possibility to make weld residual stress distribution complicated. In this study, we have performed thermal-elastic-plastic analyses to evaluate the weld residual stress produced by repair welding after piping butt-welding. The analysis results were validated by the comparison with measurements. From the analysis results with varying the repair welding conditions, we also performed structural integrity assessments related to stress corrosion cracking using probabilistic fracture mechanics analysis code PASCAL-SP. It was clearly shown that tensile stress in repair-welded region was increased and compressive stresses occurred outside the repair-welded region. Deeper mechanical cutting depth caused larger increases in tensile residual stress of repair-welded region. It was also clarified that partial repair welding might have a beneficial influence on the break probability of piping welds.

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