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K_IH and K_IC Stress Intensity Factors (14.3)

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 strength-test requirements for pipelines.”

Discussion of Criticality

Typical pipe specifications to not have specific steel chemistry requirements and therefore it will be difficult to establish a standard (K) factor when characteristics vary from mill to mill.

Discussion of Progress

SRNL advises that stress intensity factors (K) should be identified and evaluated for materials to be used for hydrogen pipelines though there is a diversity of opinion on this need particularly for lower strength steels.

Recommendations

The ASME B31.12 hydrogen task group is currently discussing a fracture mechanics approach for piping and pipeline design and fatigue analysis. Standards for hydrogen pipelines should be established and incorporated by reference into the federal code.