Cryogenic Pressure Vessel Liner Cold-Stretching
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Solution Overview
Problem
Current pressure vessels for storing cryogenic liquids, such as liquid hydrogen, face challenges with limited elastic range, weight, and high production costs due to the use of austenitic steel liners and fiber-reinforced plastic reinforcements, which lead to undesirable embrittlement under cryogenic conditions.
Innovation Solution
A pressure vessel design featuring a liner made of a non-magnetic metal alloy with a fully austenitic face-centered cubic lattice structure, cold-stretched to expand its elastic range, combined with a fiber-reinforced plastic reinforcement, utilizing specific metal alloys like 1.3974 with high nitrogen content for enhanced strength and weldability, and a method involving cold stretching and nitrogen treatment to increase yield strength and reduce material imperfections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If austenitic steel liner is used in pressure vessels for cryogenic storage, then the vessel can store liquid hydrogen, but the elastic range is deficient and the vessel becomes heavier
Solution Approach 1:
The patent changes the material parameters by using a non-magnetic metal alloy with fully austenitic face-centered cubic lattice structure instead of conventional austenitic steel. This material parameter change enables the liner to maintain high elastic range and cold toughness at cryogenic temperatures without requiring excessive reinforcement, thereby reducing overall vessel weight.
Solution Approach 2:
The patent employs a composite structure combining a metal alloy liner with fiber-reinforced plastic reinforcement. The metal alloy liner provides cryogenic compatibility and hydrogen resistance, while the fiber-reinforced plastic provides additional strength. This composite approach optimizes the weight-strength-cryogenic performance balance.
2Strength
If cryoforming is applied to increase mechanical strength of austenitic steel containers, then strength increases, but martensite formation causes embrittlement under hydrogen and cryogenic conditions
Solution Approach 1:
The patent changes the material composition parameters by selecting a non-magnetic metal alloy with specific chromium, nickel, and nitrogen content ranges that maintain fully austenitic structure at cryogenic temperatures. This compositional parameter change prevents martensite formation during cryoforming, thereby avoiding embrittlement while still achieving the desired mechanical strength enhancement.
3Strength
If stronger fiber-reinforced plastic reinforcement is applied to compensate for limited elastic range, then the elastic range is limited, but the vessel weight increases and production cost increases
Solution Approach 1:
The patent changes the liner material parameters by using a non-magnetic metal alloy with fully austenitic face-centered cubic lattice structure that inherently provides extended elastic range at cryogenic temperatures. This material parameter change reduces the need for excessive fiber-reinforced plastic reinforcement, thereby reducing both vessel weight and production costs while maintaining the required elastic range.
Data Source
AI summary
The invention relates to a method for producing a pressurised container for receiving and storing cryogenic fluids, consisting of a metal container forming a liner (12) and a sheath (14) which is applied to the liner and consists of fibre-reinforced plastic, wherein the liner (12) is formed from a non-magnetic metal alloy having a fully austenitic, cubic-face-centred grid structure and is cold-stretched by up to approximately 25%, in particular by less than approximately 15%, to increase the elastic range before the sheath consisting of fibre-reinforced plastic is applied.