Estimation of Maximum Load for Pipes With Multiple Circumferential Flaws by Limit Load Analysis

Fully plastic failure stress for a single circumferential flaw in a pipe is evaluated by the limit load criteria in accordance with Appendix C in the ASME Code Section XI and Appendix E-8 in the JSME S NA-1-2004. However, multiple flaws such as stress corrosion cracking are frequently detected in the same circumferential cross section in a pipe. Limit load analysis has been validated for pipes with multiple circumferential flaws. Quasi-static four-point bending tests were performed on Type 304 stainless steel pipes with single, double, or triple circumferential flaws. Maximum loads measured in these tests were estimated by limit load analysis for pipes with multiple circumferential flaws. All estimation results using flow stress defined by the JSME S NA-1-2008 are conservative compared to the test results. Estimation results using flow stresses obtained from tests for the pipe with a single flaw quantitatively agree with test results.