High-Temperature Flaw Evaluation (HTFE) in Cylindrical Geometries With Applied Load Histories

Abstract Recently several advancements have been made in the development of Code Case (CC) N-934 and its approval in the ASME Boiler and Pressure Vessel Code (BPVC) Section III, Div. 5 for high-temperature flaw evaluation (HTFE) applied to several metallic materials. This work summarizes the application of the CC N-934-1 (latest version) to a pipe specimen geometry with surface flaws made from ASME Code material under Section III Div. 5 (Alloy 617). Flaw growth in a combined pressure and bending load based stress is analyzed. Accordingly, this paper summarizes the effects of simple pressure, bending, and axial loading and a complex load history on the stress intensity factor (KI) and reference stress (RS) followed by the failure assessment diagram (FAD). Additional aspects of the next advancements needed to the CC N-934-1 for simplistic fatigue analysis have been identified and discussed. Results presented in this work are precursors to the understanding of flaw growth in metallics in the creep regime and provide guidance on parametric studies, choice of temperatures, and loading for usage of these materials and length of time of application in high temperature components. The use of RS, Larson-Miller parameters (LM), and the evolution of damage and time fraction accumulation to rupture from creep was evaluated.