This is the second paper in a two-paper series which covers the PRCI-funded work aimed at the development of intelligent flaw interaction rules (termed PRCI-CRES SIA-1-5 rules). The first paper focused on the development of the rules using numerical analyses. This paper covers the evaluation of the rules through full-scale burst tests and accompanying small-scale material tests.
Four full-scale burst tests were conducted on 20” and 18” OD pipe segments with SCC. The SCC colonies on the test sections were inspected using MPI, PAUT, ECA, and IWEX. The small-scale material tests were conducted to measure pipe tensile strength and Charpy impact energy. The four test sections were pressurized until burst. The burst tests were recorded using multiple video cameras to capture the global behavior and detailed crack opening process at the burst locations. With the videos and the post-test examination of the failure surfaces, the full-scale burst tests provide not only the burst pressure but also information for the validation of the fundamental principles of the new interaction rules.
The modified Ln-sec method was used to predict the burst pressure using the equivalent crack size from different flaw interaction rules and the measured pipe material properties. The PRCI-CRES SIA-1-5 rules were found to provide the most accurate and precise burst pressure prediction when factors other than flaw interaction rules remain the same.
The application of the PRCI-CRES SIA-1-5 rules can reduce unnecessary hydrotests and/or other remediation actions with accurate, not overly conservative, burst pressure prediction.