Progress: Addressed, Not Adequately
DOT Relevance: 192.51 192.65
Because of hydrogens 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.
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.
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.
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.