This paper reviews some of the original basis documents for ASME Section XI Nonmandatory Appendix G for calculating pressure-temperature (P-T) limits and recommends areas for improvement. The original Appendix G in Section XI of ASME Code was mainly based on Welding Research Council (WRC) Bulletin 175 (WRC-175). Changes have been made to Appendix G over the past 20 years such as the use of the KIC reference toughness curve instead of KIR. However, aspects of the Appendix G method still refer back to WRC Bulletin 175. The published technical literature since the development of WRC 175 could be used to enhance the Appendix in a number of areas. One such area is stress intensity factor (K) calculation procedures for thermal gradient loading at a nozzle corner. This paper will review and evaluate the available K calculation methods for a nozzle corner crack, and develop closed-form expressions for incorporation into Appendix G. Also, the following areas will be reviewed: (1) treatment of operating stresses exceeding the material yield stress, and (2) fracture toughness criteria typically used for other than reactor pressure vessel (RPV) and piping for protection against non-ductile failure. This paper will also identify areas for future improvements in Appendix G.

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