Working with hydrogen, oxygen, or high-purity fluids imposes requirements that go far beyond a standard valve. Material compatibility, gas tightness, and safety against spontaneous ignition are not optional: they are the starting conditions.
Why hydrogen requires specific valves
The hydrogen molecule can pass through materials that retain virtually any other fluid without issue, making permeation and leakage the main risks in a poorly specified installation.
Added to this is hydrogen embrittlement: certain steels and alloys lose ductility when exposed for prolonged periods to pressurized H₂, especially during loading and unloading cycles. A valve designed for this service must combine low dead-volume geometry, seats with compatible elastomers (PTFE or FFKM depending on the application), and bodies made from austenitic materials or nickel alloys that are not affected by this phenomenon.
At FHT, hydrogen ball valves are designed according to these criteria, with helium leak testing that guarantees leakage rates below the most demanding limits in the industry.
Valves for oxygen: cleanliness and compatibility above all
With oxygen, the main hazard is not leakage but ignition. In the presence of O₂ at high concentration or pressure, greasy materials, metallic particles, or excessive flow velocities can trigger violent combustion. The cleaning process—removal of hydrocarbons, particles, and moisture—is as important as the design of the valve itself.
The reference standards for this service are ASTM G93 and IGC Doc 13, which establish degreasing procedures, acceptable materials, and installation conditions. Elastomers are also restricted: virgin PTFE and FFKM are usually the only materials accepted in contact with the fluid.
FHT’s valves for oxygen service are supplied cleaned and certified for this service, with full traceability documentation covering both the materials and the manufacturing process.
Critical fluids: cryogenics, high purity, and corrosive media
The term “critical fluids” groups together very different applications, but with one common denominator: the margin for error is minimal.
Cryogenic service. Liquid nitrogen, LNG, or liquid hydrogen operate below –150 °C. At these temperatures, ordinary materials become brittle. Bodies in 316L stainless steel, cryogenic PTFE seats, and stems with extensions to prevent condensation in the packing are common requirements. FHT offers cryogenic valves tested according to the BS 6364 standard.
High purity. In the pharmaceutical, semiconductor, or food industries, contamination of the fluid by particles, lubricants, or excessive surface roughness is unacceptable. Electropolished finishes, full-drain designs, and material conformity certificates (3.1 certificates according to EN 10204) are part of the standard, not an option.
Corrosive media. Chlorine, concentrated acids, or fluids containing chlorides require bodies in Hastelloy C-276, Duplex, or even titanium when conventional stainless steel is not sufficient. The selection of body, seat, and stem materials must be carried out in a coordinated way, not component by component.
How to correctly specify a valve for these services
An incomplete specification is the most common cause of field problems. The minimum parameters that must be defined before selecting a valve are: fluid and concentration, design pressure and operating temperature (minimum and maximum), end connection standard, pressure class, and certification or additional documentation requirements.
If you have doubts about the correct configuration for your application, the FHT technical team can help you define the proper specification from the start. You can contact them through the contact page or consult the product catalog directly.