Fatigue Crack Growth (14.4)

Fatigue Crack Growth (14.4)

Criticality: High
Progress: Addressed, Not Adequately
Score: 20
DOT Relevance: 192.501 192.517

Description of Key Area

Material testing falls under Subpart J (Test Requirements) of 49 CFR 192. Per the Code, This subpart prescribes minimum leak-test and strength-test requirements for pipelines.

Discussion of Criticality

There is little knowledge other than that fatigue cracks grow 10 to 30 times faster in hydrogen embrittled materials than under the same conditions in air.

Discussion of Progress

SRNL advises that fatigue crack growth should be identified and evaluated for materials to be used for hydrogen pipelines.

Recommendations

ASME B31.12 will address this issue within the limits of available data. Further research is necessary and appropriate fatigue crack growth testing methods should be identified and documented. A database of fatigue related incidents should be established. Standards for hydrogen pipelines should be established and incorporated by reference into the federal code.