Higher Strengths (1.7)
Criticality: High
Progress: Addressed, Not Adequately
Score: 20
DOT Relevance: §192.51 – §192.65
Description of Key Area
Because of hydrogen’s low gravimetric and volumetric density,
many hydrogen transport solutions are looking to higher pressures to increase
storage/transport densities. Higher pressures lead to increased material needs
for pipelines and containers. The ability to use higher strength materials can
mitigate the need for increased material, reducing the cost and weight of
hydrogen transportation technologies.
Discussion of Criticality
Metals can be processed to have a wide range of strengths and
resistance to hydrogen-assisted fracture generally decreases as the strength of
the alloy increases. Tensile strength is not the only influential factor. Steel
chemistry can play a significant role relative to embrittlement. Many pipeline
steels are “micro-alloyed” and initial indications are that they perform better
than standard steels. Many pipe specifications are API standards which are
performance based. They specify minimum yields without chemistry requirements.
Discussion of Progress
Embrittlement studies have been performed and are currently
ongoing. UIUC is currently investigating embrittlement issues and is
coordinating with related work at SECAT, Inc., ORNL, and SRNL. A study of
embrittlement of high strength fasteners for use on hydrogen systems has been
completed by the Hendrix Group in 1998.
One ASTM standard does exist on this topic. It is ASTM
F519, the Hydrogen Embrittlement Test.
Recommendations
Research data on high strength steels needs to be completed.
Chemistry reporting must be mandatory not just of the standard elements but
also the trace elements from which are derived the “micro alloy” benefits. Confirm
whether or not this topic will be addressed by ASME B31.12. Standards for
materials of higher strength for use as hydrogen piping and containers should
be established and incorporated by reference into the federal code.
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