Weldingof Steel (9)
Criticality: High
Progress: Addressed, Not Adequately
Score: 20
DOT Relevance: §192.221 – §192.245
Description of Key Area
Welding of steel in pipelines is addressed under Subpart E of 49
CFR 192. Per the federal code, the scope of this section is as follows: “This
subpart prescribes minimum requirements for welding steel materials in pipelines.
This subpart does not apply to welding that occurs during the manufacture of
steel pipe or steel pipeline components. “
Discussion of Criticality
Modifications to the CFR may be needed to account for welding of
steel pipe to be used in hydrogen applications. It is important that all
joining methods used are adequate to prevent leakage, permeation of hydrogen, pipe
weld and HAZ embrittlement.
Discussion of Progress
Over the years, organizations such as the SRNL, SNL, ORNL, and ASME
have studied different aspects of welding of steel pipe for hydrogen use. The
research categories studied include crack growth, procedures for welding,
welding qualification, weld inspection, and appropriate weld hardness levels.
ASME has identified a knowledge gap in the study of welds for
hydrogen pipe. ASME is concerned about the effect of pressure on sustained load
cracking in welds and weld HAZs.
Recommendations
Current research regarding hydrogen pipe welds should be expanded
to include a more in-depth analysis of the research areas mentioned above.
Standards for hydrogen pipe welds should be established and incorporated by
reference into the federal code. It is important that all joining methods used
are adequate to prevent leakage, permeation of hydrogen, pipe weld and HAZ
embrittlement. These standards should address procedures for welding, welding
qualification, weld inspection, appropriate weld hardness levels, acceptable
rates of crack growth (if any), and testing of welds. Without research data,
all that the ASME B31.12 task group can do at the present is to add cautionary
notes for welding for hydrogen service and require a maximum hardness limit
that comes from NACE recommendations for sour service.
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