What safety standards apply to liquefied hydrogen vacuum-insulated pipes? What are the maintenance and inspection considerations?

The primary safety standards for applicable to this piping in the U.S. are ASME B31.3, B31.12, and NFPA 2. The editions used should be those adopted by the local jurisdiction. Design of an LH2 piping system should always be conducted and reviewed by engineers experienced in cryogenic piping design. The equipment should also be installed per NFPA 2 and NFPA 55. IT is recommended that the piping be inspected at least once per quarter. The inspection should look for corrosion, exterior damage, frayed flexible sections, proper support, and for evidence of water condensation or ice on the outer piping Ice and water condensation is indicative of vacuum degradation. The outer jacket relief device should also be inspected to ensure it is in good condition and available to operate when needed.