Per CFR §192.712(d), introduced as Part 1 of the Gas Mega Rule: “When analyzing cracks and crack-like defects, an Operator must determine predicted failure pressure, failure stress pressure and crack growth using a technically proven fracture mechanics model appropriate to the failure mode (ductile, brittle or both), material properties (pipe and weld properties), and boundary condition used (pressure test, ILI, or other).”
Furthermore, “If a pipeline is susceptible to cyclic fatigue or other loading conditions that could lead to fatigue crack growth, fatigue analysis must be performed using an applicable fatigue crack growth model.”
It’s worth noting that liquid pipelines tend to be more susceptible to pressure cycle fatigue analysis and the Mega Rule was the first regulation to require consideration of cyclic fatigue for gas pipelines.
Accordingly, per liquid Code §195.452(g), “Stress corrosion cracking (SCC) and other cracking (pipe body or weld) excavations and findings, including in-situ non-destructive examinations and analysis results for failure stress pressures and cyclic fatigue crack growth analysis to estimate the remaining life of the pipeline” must be considered as part of the information analysis aka data gathering and integration of integrity data.
