Innovative Design and Performance Study of a Carbon-Fiber-Wound Reinforced Metal Seal Tube for Ultra-High-Pressure Hydrogen Solenoid Valve

A 70 MPa class hydrogen solenoid valve needs a metal seal tube with a high strength margin at the specified safety factor (proof pressure 175 MPa). A lightweight scheme is therefore proposed in which the thin-walled tube is reinforced by carbon-fiber hoop winding. S31603 austenitic stainless steel is ordinarily selected as the primary material for this pressure-bearing component owing to its excellent corrosion resistance and favorable hydrogen-embrittlement resistance. However, its low yield strength means that satisfying the strength requirement only by increasing the wall thickness would raise the structural mass, widen the non-magnetic gap and reduce the electromagnetic efficiency. To avoid this, a thin-walled S31603 tube is used as the metallic liner, and a mechanical model of the metal–composite structure is established on the basis of composite netting theory and thick-walled cylinder elasticity. The winding-layer thickness and the process parameters are then determined, and the design is verified by finite element analysis and pressure testing. The results show that, at the 175 MPa proof pressure, a 3 mm thick all-metal seal tube has an elastic limit of only about 65.4 MPa, far below the requirement. After carbon-fiber wet winding, the composite seal tube reaches the required strength, with a total wall thickness of only about 3 mm and a much lower mass. Because the carbon-fiber layer is non-magnetic, the structure improves the pressure-bearing capacity while introducing almost no additional reluctance. It effectively decouples the contradiction between the structural strength and the magnetic-circuit efficiency and offers a new route for the lightweight design of hydrogen fluid-control components.