Permeation
Hydrogen moves through the body of an elastomer, not just around it. Every elastomer lets some through; fluoroelastomers are among the lower-permeability families.
Hydrogen (H₂) Sealing Solutions
High‑Performance Seals for Hydrogen Service
Explore VERTEX FKM and FFKM seals selected for the demands of hydrogen valves, regulators, compressors, storage and process equipment.
Why hydrogen is different
What Makes Hydrogen Hard to Seal
Hydrogen is the lightest molecule and one of the smallest. A seal that works well in oil, water or natural gas can still fail in hydrogen – often through several of these factors at once.
Rapid gas decompression
A leading cause of elastomer seal failure in high-pressure gas service. See how it happens below.
Pressure cycling
Filling, holding, venting and refilling repeat again and again. The seal has to keep its shape and sealing force through every cycle, not just pass a single pressure test.
Temperature swings
Heat from compression, pre-cooled gas at dispensers, cooling as storage vessels empty and outdoor conditions. The compound has to stay elastic across the full range.
Extrusion
At several hundred bar, a seal can be forced into the clearance gap and nibbled away, with the damage growing on every cycle.
Co-media and purity
Lubricants, hydrocarbons, H₂S, moisture and cleaning media can all reach the seal alongside hydrogen. High-purity service also calls for clean, low-contamination materials.
Good to know: hydrogen embrittlement affects metal parts such as springs, fasteners and housings. It is not how elastomer seals fail.
How rapid gas decompression damages an elastomer seal
Saturation
Under pressure, hydrogen dissolves into the elastomer.
Pressure drop
The system vents faster than the gas can diffuse out.
Gas expansion
Trapped gas expands, forming internal voids and blisters.
Crack growth
Cracks grow with each cycle until the seal splits or leaks.
RGD is also called explosive decompression and resistant compounds are often described as AED (anti-explosive decompression) grades. RGD resistance and permeation resistance are separate properties, so both need assessing.
Seal types
Seal Profiles for Hydrogen Equipment
The VERTEX hydrogen grades are moulded into a range of seal profiles, in standard and custom sizes.
O-rings
Static and slow-moving seals for valves, regulators, manifolds, fittings and storage systems.
X-rings
Four-lobe profile with lower friction and better stability than an O-ring on moving stems and shafts.
Backup seals
Support the primary seal and close the extrusion gap at high pressure.
U-cup seals
Pressure-energised rod and piston seals for valve actuators and reciprocating equipment.
Lip and wiper seals
Keep contamination out and fluids in on moving rods, stems and shafts.
Packing elements
Stacked sealing sets for valve stems and other adjustable high-pressure glands.
Gaskets
Flange, cover and housing seals for process equipment exposed to heat and aggressive media.
Diaphragms
Flexible pressure-sensing and isolating elements for regulators, pumps and instruments.
Material portfolio
VERTEX Materials for Hydrogen Service
Three grades from the VERTEX elastomer range, each chosen for a different part of the hydrogen operating envelope.
FKM · Viton® GFLT gradeLow-temperature grade
VERTEX FC 33
For outdoor installations, pressure-reduction stages and systems with cold starts.
- Stays flexible at lower temperatures than standard FKM
- Low volume swell in fluids under pressure
- Very good resistance to oils, lubricants and hydrocarbons
FKM · GF typeHigh-temperature FKM
VERTEX FC 13
For hot hydrogen combined with oils, lubricants or hydrocarbon process streams.
- 70% fluorine content for broader chemical resistance and lower swell than standard FKM
- Holds sealing force through long exposure to heat
- High tensile strength and modulus to resist extrusion
FFKMSevere-duty grade
VERTEX F 16
Perfluoroelastomer developed for high temperature and rapid gas decompression resistance.
- Suits hydrogen streams carrying sour gas, solvents or aggressive process chemicals
- The step up when FKM grades reach their temperature or chemical limits
Technical data
Material Properties
Specification values from ISMAT technical data sheets.
| Property | VERTEX FC 33FKM GFLT | VERTEX FC 13FKM GF | VERTEX F 16FFKM |
|---|---|---|---|
| Hardness ASTM D2240, Shore A | 90 ± 5 | 90 ± 5 | 85 ± 5 |
| Density ASTM D792, g/cc | 1.85 ± 0.05 | 1.83 ± 0.05 | – |
| Tensile strength ASTM D412, MPa min. | 12 | 14 | 16 |
| 100% modulus ASTM D412, MPa min. | – | 7 | – |
| Elongation at break ASTM D412, % min. | 100 | 100 | 75 |
| Compression set ASTM D395, % max. | 25 22 h at 200 °C, Method B | 25 22 h at 200 °C, Method B | 35 70 h at 200 °C |
– Not specified on the data sheet. The F 16 compression set is measured over a longer period, so it is not directly comparable with the FKM grades.
Operating temperature range
VERTEX FC 33
VERTEX FC 13
VERTEX F 16
Ranges from ISMAT technical data sheets; actual limits vary with seal design and application parameters.
Selection guide
Choosing the Right Grade
How the three grades compare with each other for common hydrogen service requirements.
| Requirement | VERTEX FC 33 | VERTEX FC 13 | VERTEX F 16 |
|---|---|---|---|
| Rapid gas decompression | Good | Good | Excellent |
| Low-temperature service | Very good | Limited | Good |
| High-temperature service | Good | Very good | Excellent |
| Sour gas (H₂S) | Good | Good | Excellent |
| Aggressive chemicals acids, ketones, esters, solvents | Good | Very good | Excellent |
| Cost efficiency | High | High | Premium grade |
Relative rating; confirm by testing in your application.
Applications
Across the Hydrogen Value Chain
Whether it comes from reforming or electrolysis, hydrogen passes through similar equipment on its way to the user.
Production
Reformer gas handling and electrolyser balance of plant: gas valves, separators, dryers and purification skids.
Compression
Static seals on reciprocating and diaphragm compressors: valve covers, cylinder heads, joints and packing cases.
Storage
Stationary storage vessels, tube trailers and cylinder bundles, with their valves and manifolds.
Transport and distribution
Pipelines, hydrogen–natural gas blending, pressure regulation and metering skids, shut-off and control valves.
Refuelling infrastructure
Station valves, priority panels, high-pressure manifolds and instrumentation fittings upstream of the dispenser.
Refinery and process hydrogen
Hydrotreaters, hydrocrackers, recycle-gas compressors and process valves where hydrogen meets hydrocarbons and H₂S.
Design guidance
Designing the Seal Housing for Hydrogen
The same compound can pass or fail depending on how the housing is designed. These points apply to O-rings and most other elastomer seals and are worth checking early.
Keep the seal in its groove
Tight extrusion gaps and PTFE or PEEK backup rings prevent extrusion at high pressure. Why backup rings matter
Balance the housing fill
Enough constraint to limit seal expansion during decompression, with room left for thermal expansion and media swell.
Get the compression right
Correct squeeze or interference reduces the area exposed to permeation and improves low-pressure sealing, within the compound's compression-set limits.
Review the seal section
Thinner seal sections hold less dissolved gas and release it faster, which generally improves decompression resistance.
Specify a fine surface finish
Gas sealing faces need a finer finish than liquid service. Scratches across the sealing face become leak paths.
Control the decompression rate
Where the process allows, slower depressurisation lets absorbed gas diffuse out before it can expand.
FAQ
Hydrogen Sealing: Common Questions
Can FKM (Viton®) seals be used for hydrogen?
Yes. FKM is widely used in hydrogen valves, regulators and compressors for its chemical and high-temperature resistance. Its main limit is the cold: standard FKM stiffens at around −15 °C to −20 °C, which is why low-temperature GFLT grades are used for colder duty.
Is FFKM always better than FKM for hydrogen?
Not always. FKM grades are often fully adequate for clean hydrogen at moderate temperatures and they cost considerably less. FFKM earns its place when hydrogen is combined with aggressive media, very high temperatures or demanding decompression conditions.
What Shore hardness is best for hydrogen seals?
For high-pressure gas service, 85–90 Shore A compounds are the usual choice because they resist extrusion and decompression damage better than softer grades. Softer compounds seal more easily at very low pressure, so the right hardness depends on the pressure range.
ADVANCE with ISMAT
Discuss Your Hydrogen Application
Tell us about your operating conditions and our engineers will recommend a grade and seal design. Seals are made with compound data and sample seals available to support your qualification.
Share with your enquiry
- Pressure range and decompression rate
- Minimum and maximum temperature
- Hydrogen purity and other media
- Static or dynamic duty, gland dimensions
- Pressure-cycle count and required standards
Disclaimer: The information on this page is general technical guidance and is not a service-life, pressure or temperature rating. Seal performance depends on compound, gland design and operating conditions; application-specific testing is recommended for critical hydrogen service, particularly where failure may result in injury or damage.
Viton® is a registered trademark of The Chemours Company.