Valves for Compressed Gas Service
All valves must be suitable for hydrogen service and for the specific operating conditions.
See the discussion regarding material selection in Compressed Gas Storage Vessels. Note that valves often have parts made of materials that are different than the valve body material. For example, some austenitic stainless steel valves have stems that are made from martensitic stainless steel. (Austenitic stainless steel is generally considered acceptable for hydrogen service, whereas martensitic stainless steel is not.) When selecting valves, the materials for all of the valve components should be verified for suitability.
See the discussion regarding fitting types in Compressed Gas Fittings and Joints. The same considerations as for fitting types should be made when selecting valve end connections.
Valve stem seals frequently leak in service. Consideration to valve stem seal performance and reliability should be given when selecting valves.
Many valve bonnet gaskets and stem seals are not fire-resistant. When leaks resulting from exposure to fire are not acceptable, only fire-resistant valves should be used. See API STD 607/ISO 10497 - Fire Test for Soft-Seated Quarter-turn Valves.
Most types of valves used by industry in flammable gas service are acceptable. Ball valves are frequently chosen because of their superior leak tightness through the seat and because fire-resistant versions are generally available.
Pneumatic operators are usually chosen for remotely operated valves so that potential ignition sources are remote from the valve.