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Hydrogen is emerging as a critical component of the global energy transition, yet its physical properties create severe challenges in valve systems. The combination of high-pressure, small molecular size, and sustained static sealing conditions can expose weaknesses in traditional materials, forcing engineers to reexamine how valves are designed for hydrogen infrastructure.
By Kerry Drake- Senior Technology Manager, Plastics R & D, Philippe Allienne, Business Development
Manager – Clean Energies, and Sam Hippe, Plastics Design and Development
Research Engineer – Greene Tweed
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Hydrogen is moving from demonstration projects to large-scale infrastructure. According to the Hydrogen Council, the global clean hydrogen pipeline now represents more than USD110 billion in committed investment by 2030, reflecting the rapid acceleration of deployment across multiple regions. Electrolysers, compression systems, pipelines, and storage facilities are being rolled out across energy networks designed to support decarbonisation and renewable power integration. Within these systems, valves perform essential roles, isolating equipment, controlling flow, and ensuring safe containment of hydrogen under demanding operating conditions. The reliability of these valves is fundamental to the viability of hydrogen infrastructure. Yet hydrogen presents a unique set of challenges that conventional valve materials were never designed to manage. Hydrogen’ s extremely small molecular size, combined with high operating pressures and long periods of static sealing, can gradually degrade the materials used in valve seats and seals. Hydrogen’ s unique behaviour
Hydrogen behaves very differently from the gases traditionally handled by industrial valve systems. With a molecular diameter of approximately 0.29 nanometers, compared with around 0.38 nanometers for methane and 0.33 nanometers for nitrogen, hydrogen is the smallest molecule encountered in industrial gas service.
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This small size enables hydrogen to diffuse through microscopic pathways that remain effectively sealed under other operating conditions. Diffusion rates for hydrogen in many polymers can be several times higher than for larger molecules, increasing the likelihood of permeation over time. At the same time, hydrogen systems typically operate under far more demanding pressure conditions. While conventional gas distribution systems often run below 100 bar, hydrogen compression, storage, and refuelling infrastructure can exceed 700 bar in high-pressure applications. These elevated pressures further increase solubility and diffusion rates withi sealing materials, accelerating permeation effects. This combination of pressure, diffusion, and sustained loading gradually alters material properties. Seals may swell or soften. In valve assemblies where tight tolerances are essential for leak-tight performance, even slight changes in material behaviour can compromise sealing integrity. Hydrogen also introduces additional risks for metallic components. Multiple metals used in conventional energy infrastructure are susceptible to hydrogen embrittlement, where absorbed hydrogen weakens the material structure and increases the risk of cracking or sudden failure. Highstrength alloy steels, commonly used in pressure-containing components, are particularly vulnerable, while certain grades of stainless steel can also experience degradation under hydrogen exposure. |
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