Abstract: Flaws detected in in-service inspection of dissimilar metal weld joints were evaluated in this paper according to Appendix C and Appendix H of ASME BPVC Section Ⅺ. In the flaw safety evaluation, a method using a surface flaw evaluation diagram based on Appendix C was introduced and applied. This allows the evaluation of any surface indication at dissimilar metal weld joints, without additional knowledge of fracture mechanics required.