Progress: Addressed, Not Adequately
Some metallic components, including cylinders, cylinder liners, valve components, and tubing may incorporate welded construction.
Welding of metals can introduce stress concentrations, and reduce strength and elongation of welded materials. Welding of some austenitic stainless steels that are resistant to hydrogen embrittlement can produce martensitic structures that are subject to hydrogen embrittlement.
Welded metallic components are currently being used in hydrogen storage. However, the use of welded components becomes more of an issue as hydrogen gas pressure increases.
Industry and DOT should be developing performance based requirements in standards and regulations that demonstrate capability of any welds in components for hydrogen storage are of sufficiently strong and resistant to hydrogen embrittlement. It may be required to limit the use of welds in hydrogen storage components, to specify that only certain metals can be welded, or that higher safety factors will be required for welded components.