On the selection of isolation valves for liquefied hydrocarbon spheres
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The SH3136-2003 standard specifies that the material of the valve body in liquefied petroleum gas systems should be carbon steel, and it should possess the same low-temperature resistance and H2S corrosion resistance as the material of the tank. Globe valves are preferred for use as shut-off valves; when gate valves or ball valves are used, they must be equipped with a pressure relief mechanism in their valve chambers. What is the purpose of installing a pressure relief mechanism in the valve chamber, what is the structure of such a mechanism, and why does a globe valve not require a pressure relief mechanism?
In my understanding, the function of the pressure relief mechanism in the valve chamber is to prevent damage: after the valve is closed, the medium trapped within the valve chamber gradually heats up and vaporizes, resulting in an increase in local pressure. A pressure relief device is installed to release this pressure in a timely manner.