A Sensitivity Study: Effects of Toughness Values on Fatigue Crack Growth Analysis of Just-Survived Flaws Following a Pressure Test

The Pipeline and Hazardous Materials Safety Administration (PHMSA) issued a Notice of Proposed Rulemaking (NPRM)1 on April 8, 2016 that is expected to have an impact on the pipeline industry’s approach to crack growth analyses. Specifically, the NPRM defines values for pipe toughness that should be used in analyzing crack anomalies that are subjected to fatigue growth for instances in which known or measured pipe toughness values are not available. Pipeline Operators conduct these types of analyses to derive remaining life values which can in turn be utilized to establish pipeline integrity reassessment intervals. Thus, the impacts of this NPRM are felt by all pipeline operators who own assets in which cracking is considered a threat. The goal of this paper is to quantify the effects of using the NPRM defined toughness values in pressure test assessments for scenarios where pipe toughness values are unavailable.