What materials are suitable for piping hydrogen and hydrogen mixtures? Are there any guides or references available for selecting piping and fittings for hydrogen applications?

In laboratories, 316 stainless steel tubing is frequently the first choice for small flow and pressures less than 2800 psi (19 MPa). See Best Practices: Material Compatibility for hydrogen compatibility with various materials. Always work within manufacturer’s pressure ratings adjusted for temperature. Read and follow manufacturer’s instructions on making up tubing fittings, avoid threaded fittings, and properly purge with nitrogen, helium or other inert gas to remove air before introducing hydrogen.