Improvements to surface-cracked pipe J-estimation schemes: Comparison of experiments and analytical predictions

This paper summarizes the analysis developments and improvements to evaluate the safety margins of circumferentially surface-cracked piping. This work was performed for the US Nuclear Regulatory Commission (NRC) as part of the research program entitled Short Cracks in Piping and Piping Welds that specifically addressed short circumferential cracks typically used in leak-before-break (LBB) analysis or in-service flaw evaluations. The focus of this paper is to describe the improvements made to existing J-estimation schemes such as the SC.TNP and SC.TKP methods developed previously for surface-cracked piping. Also,m a new J-estimation scheme, The SC.ENG method, was derived to evaluate the crack driving force for these pipes. The predictions for J are compared with those from detailed finite element analyses. The predicted maximum load as well as those at crack initiation are compared with experimental data on full-scale pipe tests.