[ sealing ]
of hydrogen, which differ significantly from those of other gases. Hydrogen’ s small molecular size requires careful consideration in transport infrastructure.
Key challenges in sealing for pipeline transport include:
• Permeation risks: Due to its small molecular size, hydrogen poses a higher risk of permeating through seals. To mitigate leakage, it is vital to use sealing materials with low permeability. Therefore, soft sealing materials, elastomers or fluoropolymers should be selected carefully to minimize these risks.
• Material degradation: Hydrogen embrittlement can progressively weaken metal components. Sealing materials resistant to hydrogen penetration and degradation are essential to maintaining pipeline integrity.
Compressed gas transport Compressed gas transport involves storing hydrogen at high pressures in tube trailers or cylinder bundles, typically between 200 and 700 bar. Commonly used for smaller-scale transport over short distances, this method relies on hydrogen compression to reduce volume and enable efficient storage and handling. However, transporting hydrogen at high pressures poses considerable sealing challenges.
• Pressure fluctuations: Hydrogen transport involves frequent pressure changes during loading, unloading, and transit, which can cause seal deformation or fatigue, potentially compromising long-term performance.
• Temperature variations: The compression and expansion of hydrogen result in substantial temperature fluctuations. Seals must be made from materials that maintain their elasticity and resilience to handle these temperature fluctuations without losing their sealing capabilities.
• Leakage concerns: At elevated pressures, even minor imperfections in seals can lead to leakage. Minimizing leakage is essential for ensuring safety, performance, and efficiency in hydrogen transport systems.
Liquid hydrogen( LH 2
) transport
Transporting liquid hydrogen is employed when higher storage density is required. It is typically transported using road tankers and storage tanks, with potential future maritime applications. Because liquid hydrogen must be kept at cryogenic temperatures of −253 ° C( −423 ° F), maintaining a stable environment is critical for safety and efficiency, introducing several unique sealing challenges:
• Extreme cold temperatures: At cryogenic temperatures, materials contract and may become brittle, necessitating the use of seals with flexibility at low temperatures. To prevent failures, seals must maintain maximum leak tightness under these extreme conditions.
• Vapor leakage risks: Even minor leaks in cryogenic systems can cause boil-off losses, where liquid hydrogen vaporises and escapes. This is a major concern, as it not only leads to fuel wastage but also poses safety hazards. Seals must be designed to prevent even the smallest leaks.
• Ice formation: At such low temperatures, moisture can freeze and form ice, potentially degrading sealing surfaces and impairing seal performance. Addressing this challenge requires specialized materials and custom design solutions that accommodate ice formation without compromising seal integrity.
Reliable sealing for extreme H 2 conditions
Several key factors impact the safety and performance of hydrogen pipelines, storage tanks, and critical infrastructure. Whether the challenge involves high pressures, temperature fluctuations, or chemical exposure, effective sealing solutions are essential to ensuring long-term, leak-tight performance.
56 Hydrogen Tech World | Issue 21 | April 2025