In-service inspection for the weld joints of piping in Korea nuclear power plant is performed in compliance with ASME Boiler and Pressure Vessel Code Section XI or Korea Electric Power Industry Code (KEPIC) MI. A detected flaw that exceeds the size of allowable flaws may be evaluation by analytical procedures such as ASME B&PV Code Section XI Appendix C or H. The evaluation methodology provided in the Appendix C is based on the three conditions that govern pipe failure: limit load, elastic-plastic fracture mechanics and linear elastic fracture mechanics. The evaluation methodology provided in the Appendix H is based on the failure assessment diagram (FAD) approach. In this study, the characteristics of each evaluation methodology are analyzed. The results of this research can be used for evaluations for flaws in piping weldments.