Engineering leak-before-break analyses of pressurized piping: Part I - Crack opening displacement

The present work presents methods to estimate elastic-plastic COD for circumferential through-wall cracked pipes for the Leak-Before-Break analysis of pressurized piping. Proposed methods are based not only on the GE/EPRI approach but also on the reference stress approach. For each approach, two different estimation schemes are given, one for the case when full stress-strain data are available, and the other for the case when only yield and ultimate tensile strengths are available. For the GE/EPRI approach, a robust way of determining the R-O parameters is proposed, not only for the case when detailed information on full stress-strain data are available but also for the case when only yield and ultimate tensile strengths are available. The COD estimates according to the GE/EPRI approach, using the R-O parameters determined from the proposed R-O fitting procedures, overall compare well with the published pipe test data. For the reference stress approach, the COD estimates according to the method based both on full stress-strain data and on limited tensile properties are in good agreement with pipe test data. In conclusion, experimental validation given in the present work provides sufficient confidence in the use of the proposed method to practical LBB analyses, even when information on material's tensile properties is limited.