Cryogenic valve, as the name suggests, is for delimiting the working temperature of valves that can work in cryogenic low temperature conditions. Usually, the valve whose working temperature is below -40 degrees is called cryogenic valve.It is mainly used for liquefaction, separation, transportation and storage of gas. The temperature can reach up to -270 degrees. There are gate valves, globe valves, check valves, ball valves, butterfly valves and throttle valves.
In recent years, ultra low temperature valves are used more and more widely. They are one of the most important equipments in petrochemical industry, air separation, natural gas and other industries. Their working medium is not only low in temperature, but also low in temperature，And most of it is toxic, flammable and explosive, and has strong permeability, so it decides a lot of special requirements for the material and design of the valve. It is not only required to work normally at the set temperature, but also to ensure the working performance at normal temperature.
The low-temperature valve valve is higher than the normal temperature valve, and the lengthened valve is used. The purpose is to reduce the heat in the incoming device, ensure that the temperature of the stuffing box part is above 0 C, so that the filler can work normally; prevent the froth or freezing part of the valve stem and the upper part of the valve cover due to the undercooling of the stuffing part.
Long necked valve cover design is mainly the design of the neck length L, L refers to the stuffing to the bottom of the sealing surface of the seat distance, the coefficient of thermal conductivity, and its material thermal conductivity and surface area coefficient, cooling area and other factors, more complicated calculation, generally by the experimental method for.
The temperature is higher than that of -100 C can be used ferritic stainless steel, a temperature lower than -100 DEG C when the selection of austenitic stainless steel, low and small caliber valve can be used for copper alloy or Aluminum Alloy, the valve should be able to adequately support the temperature change caused by the expansion and contraction, and the structure is not the seat part of the permanent deformation caused by temperature change.
