High Temperature Flaw Evaluation Code Case: Technical Basis and Examples

Abstract The Working Group on High Temperature Flaw Evaluation, which currently reports to both Section XI and Section III Division 5, has developed Code Case to address high temperature flaw evaluation. The evaluation procedures are based on accepted methods used by other Code bodies around the world. The Code Case integrates the creep rupture rules of Section III Division 5 and the fracture rules in Section XI which are enhanced to address high temperature crack growth. This Code Case will eventually reside in Section XI Division 2 within the Reliability and Integrity Management Program. The purpose of this procedure is to evaluate the growth of a single, characterized flaw for a defined evaluation period in a metallic component where the future thermomechanical loads are known or approximated. The procedure describes the growth of the flaw under periods of constant primary load. Crack growth is accumulated in discrete increments over a series of time increments Δt and continues until one of the following occurs: (i) The remaining ligament fails due to the interaction of net section yield or unsteady time independent crack growth, evaluated using a Failure Assessment Diagram (FAD) defined with Section XI rules. (ii) The remaining ligament fails due to creep rupture over a time less than the time increment Δt using Section III Division 5 rules. (iii) The crack exceeds the depth limits for specific components provided in the relevant Section XI appendix. (iv) The simulation time reaches the end of the evaluation period. Several application examples are provided.