Safety under high pressure: reliable seals for hydrogen systems

H₂ pressure vessels with high-quality seals – minimised leak rates for maximum safety.(Image source: Angst+Pfister AG)

Reliable sealing solutions are a crucial factor in hydrogen systems – they prevent leaks, increase safety and extend the service life of plants.

Imagine a hydrogen storage tank at 700 bar. A barely perceptible, almost silent leak can cause pressure losses, trigger plant shutdowns or, in the worst case, promote ignition. Whether safety is guaranteed or a risk arises is often determined by components that are only a few millimetres in size: seals.

Hydrogen is considered a key energy source of the future – for mobility, stable networks and the decarbonisation of energy-intensive industries. However, its success depends largely on the integrity of the components that contain it. If the seal fails, the ramp-up process comes to a standstill. Reliable sealing systems are therefore not a minor detail, but a key technology for the transition from pilot project to series production. In applications from -40 °C to +150 °C and at pressures up to 1,000 bar, even a micro leak can cause energy losses, safety risks and system failures. Optimally matched materials and designs are crucial.

High-pressure H₂ pressure vessel with optimised valve and flange seals (Image Source: AdobeStock / Fokke Baarssen)

This is where seal manufacturer Angst+Pfister comes in with specially developed solutions. These are designed to withstand hydrogen permeation, extreme pressures, temperature fluctuations and rapid gas decompression (RGD) – and to ensure a high level of safety even under the most demanding conditions.

Hydrogen as a material challenge

Sealing hydrogen systems is technically challenging. As the smallest molecule, hydrogen penetrates materials more easily than other gases. The requirements for leakage rates and tolerances are correspondingly strict. At the same time, its high flammability in air increases the risk: even minor leaks can cause ignition, explosions or pressure relief. The possible consequences range from personal injury to significant damage to infrastructure.

Components in electrolysers, fuel cells, compressors, storage tanks, valves and connections must therefore function reliably under extreme conditions:

Pressures up to 1,000 bar
Temperature ranges from –40 °C to +150 °C
Dry operating conditions with dynamic seals
Very low permissible leakage rates
Continuous exposure to 100% hydrogen
Stresses caused by rapid gas decompression (RGD) and hydrogen embrittlement

Spring-loaded seals (Image source: Angst+Pfister AG)

Conventional elastomers often reach their limits early on in this area – for example, due to permeation, split extrusion, internal cracking or structural damage. The result: compromised system integrity, reduced service life and increased safety risks. Materials with particularly low permeation and proven RGD resistance are therefore essential for reliable hydrogen applications.

Specially developed materials and geometries

To meet the specific properties of hydrogen, optimisation begins at the molecular level. Specialised elastomers such as FKM, EPDM and HNBR, as well as high-performance thermoplastics such as PTFE and UHMW-PE, are specifically designed to resist diffusion, extrusion and RGD.

However, the choice of material alone is not enough. Only in combination with application-specific geometries – such as O-rings, PTFE lip seals, spring-loaded profiles or support rings – can a system be created that seals reliably under pressure, minimises extrusion and remains stable over a wide temperature range.

Spring-loaded seals (Image source: Angst+Pfister AG)

Each solution is tested and validated in a 100% hydrogen environment. The test protocols include tests for permeation, leakage, ageing, durability and RGD – at pressures up to 1,000 bar. Supplemented by specialised laboratories and external certifications, this creates a robust safety basis that exceeds current standards.

The portfolio is characterised by extremely low hydrogen permeation and high RGD resistance, validated according to NORSOK M-710 and ISO 23936-2. In addition, it offers broad temperature stability, suitability for static and dynamic applications, and high extrusion resistance even under demanding pressure cycles. Optimised geometries for valve seats, housings, connections, compressors and fuel cells further contribute to efficiency and durability.

The combination of high-performance materials, tailor-made designs and hydrogen-specific test validation results in solutions that not only meet existing safety requirements but also take them to the next level.

Proven performance in practice

Real-world testing is crucial to reliably prevent leaks. The sealing systems developed are based on hydrogen-specific test procedures with clearly measurable results: very low permeation values, RGD resistance and stable performance under extreme pressure and temperature conditions. Internal test laboratories and external certifications create transparency and trust – for greater operational safety, longer service life and technical competitive advantages.

Each seal is developed, tested and validated in collaboration with partners – including:
Complete material traceability
Verified test protocols (permeation, leakage, ageing, RGD)
Designs optimised using finite element analysis (FEA)
A broad, application-oriented material portfolio
Comprehensive support from engineering to logistics
European ‘local-for-local’ manufacturing

Practical example: High-pressure accumulators up to 1,000 bar

A manufacturer of hydrogen storage systems was confronted with premature seal failures in high-pressure tanks. Leaks occurred after only around 10,000 cycles.

A customised sealing concept was then developed, consisting of special PTFE lip seals, PEEK spring elements and corner support rings to prevent extrusion. After more than 60,000 test cycles in 100% hydrogen, the system remained leak-free and showed no signs of embrittlement. Intermediate maintenance was eliminated.

‘Hydrogen seals are not just a question of chemical resistance. It's about ensuring diffusion, pressure resistance and safety margins under extreme conditions. That's exactly why we have built up a validated portfolio of sealing materials,’ says Lorena Casasola, materials engineer at Angst+Pfister.

Conclusion

Hydrogen opens great opportunities – provided that the materials used already deliver the required performance today. The tested and validated sealing solutions made of elastomers and thermoplastics meet the increasing requirements in mobility, storage and infrastructure.

They are used by leading manufacturers throughout Europe. The aim remains to continuously develop test validation, materials science and application-specific support. This results in solutions that guarantee safety, reliability and performance under real-world conditions.