Cryogenic valves refers to a valve that can be used under low temperature conditions. Generally, a valve with a working temperature lower than -40 ° C is called a Cryogenic valves, and Cryogenic valves includes Cryogenic ball valve, Cryogenic gate valve, Cryogenic shutoff valve, Cryogenic butterfly valve, and Cryogenic check valve. Etc., mainly used in chemical equipment such as 300,000 tons of ethylene and liquefied natural gas. The output of liquid low-temperature medium such as ethylene, liquid oxygen, liquid hydrogen, liquefied natural gas, liquefied petroleum products, etc., is not only flammable and explosive, but also vaporizes when heated, and expands several hundred times in volume when gasified. Cryogenic valves are one of the most important equipments in the petrochemical, air separation, natural gas and other industries. The quality of their products determines whether they can be produced safely, economically and continuously.