Development and Performance of Elastomer Seals for Hydrogen Storage and Distribution Systems: Challenges, Solutions, and Future Perspectives—Part II: Component-Level Performance, Design, Modeling, and Qualification of Elastomer Hydrogen Seals

The expansion of hydrogen storage and distribution infrastructure demands elastomeric seals that maintain integrity under high pressure, thermal variations, pressure cycling, and rapid decompression. Hydrogen permeation, swelling, mechanical degradation, and gas-induced damage can impair sealing performance and increase leakage risk. This review examines elastomeric hydrogen seals from a component-level perspective, building on material characterization to assess how formulation, operating conditions, and seal design affect reliability. The literature is organized around elastomer formulations, hydrogen transport and property evolution, degradation and durability, and seal performance, numerical modeling, and qualification. Particular emphasis is placed on the interaction between hydrogen uptake and desorption, dimensional recovery, contact-pressure retention, groove geometry, squeeze, extrusion, and rapid gas decompression resistance. Seal failure results from coupled processes, including swelling, cavitation, blistering, crack growth, fatigue, aging, and loss of sealing contact. Existing qualification methods remain fragmented and do not consistently represent realistic hydrogen exposure and service cycles. More reliable seal design and lifetime prediction require standardized testing protocols and integrated experimental–numerical assessments connecting material behavior with component-level leakage and durability.