Composite sealing ring for low-temperature valve

Abstract

The invention relates to a composite sealing ring for a low-temperature valve, and belongs to the technical field of fluid control valves. The sealing ring comprises a sealing ring jacket made of modified polytrifluorochloroethylene, a hollow metal energy storage spring with a circular section is clamped in an annular groove with a C-shaped section formed by the section of the sealing ring jacket and comprises a spring strap wound outside a metal rubber ring with the circular section, the ratio of the inner distance between two surrounding edges in a natural state to the diameter of the metal energy storage spring is 0.7-0.9, the ratio of the maximum outer distance formed by unfolding the two surrounding edges after clamping the metal energy storage spring and the length of a base edge to the depth of a sealing groove to be embedded is 1.1-1.3, and metal materials in the metal rubber ring are as same as those of the metal energy storage spring. The sealing ring appropriately solves the problem of serious reduction of sealing specific pressure caused by the expansion coefficient difference between a nonmetal material and a metal material at a low temperature and solves the problem that the materials are hard and brittle at a deep-cold temperature, and reliable sealing of the valve in a -196 DEG C to -269 DEG C ultra-low temperature environment can be practically achieved.

Description

technical field [0001] The invention relates to a sealing ring, in particular to a composite sealing ring for low temperature valves, and belongs to the technical field of fluid control valves. Background technique [0002] The petroleum, chemical and gas industries are developing rapidly with liquefied natural gas (LNG) as an emerging energy source. The main component of natural gas is methane. After dehydration, refining and cooling, it is cooled to liquefied natural gas at a low temperature of -162°C. The remarkable feature of LNG is that the volume of gas is about 600 times that of liquid in the same standard state. People take advantage of this characteristic of LNG to make the storage and transportation of LNG more convenient, and save a lot of cost in storage and transportation. Since the temperature of LNG under normal pressure is -162°C, and it is flammable and explosive, when designing LNG ultra-low temperature valves, higher and stricter requirements are put for...

AI Technical Summary

Problems solved by technology

Because at low temperature, the expansion coefficient of non-metallic materials is much larger than that of metal materials, it is easy to make the shrinkage at low temperature different from that of metal seals, valve bodies and other matching parts, resulting in serious sealing specific pressure. reduced resulting in unsealable

Also, most non-metallic materials harden and become brittle at cryogenic temperatures, losing ductility, causing cold flow and stress relaxation, which can lead to seal failure

In addition, under low temperature conditions, the strength and hardness of metal materials increase, but the plasticity and toughness decrease, showing different degrees of low temperature brittleness, which seriously affects the sealing performance of valves.

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