The Difference And Selection Between Cast Steel Check Valve And Ordinary Normal Temperature Valve

Cast Steel Check Valve As the name implies, it is a valve that can work in deep cold low temperature conditions. The working temperature is usually defined as a valve with a working temperature below -40℃, which is called a cast steel check valve. It is mainly used in equipment for gas liquefaction, separation, transportation and storage, and the use temperature can reach below -270℃. Currently, there are gate valves, stop valves, check valves, ball valves, butterfly valves and throttle valves.

In recent years, the use of cast steel check valves has become more and more extensive. It is one of the indispensable important equipment in industries such as petrochemicals, air separation, and natural gas. Its working medium is not only low in temperature, but also most of it is toxic, flammable and explosive, and has strong permeability, which determines many special requirements for valve materials and design. It is not only required to work normally at the set temperature, but also to ensure working performance at room temperature.

Compared with normal temperature valves, the stuffing parts of cast steel check valves are all elevated, and extended valve stems are used. Its purpose is to reduce the heat transmitted from the outside to the device; to ensure that the temperature of the stuffing box is above 0℃ so that the stuffing can work normally; to prevent the valve stem in the stuffing box and the parts on the upper part of the valve cover from frosting or freezing due to the overcooling of the stuffing box.

The design of the long-necked valve cover is mainly the design of the neck length L. L refers to the distance from the bottom of the stuffing box to the upper surface of the upper sealing seat. It is related to the thermal conductivity, thermal conductivity area, surface heat dissipation coefficient, heat dissipation area and other factors of the material. The calculation is relatively cumbersome and is generally obtained by experimental method. Ferritic stainless steel can be used when the temperature is higher than -100℃, and austenitic stainless steel can be used when the temperature is lower than -100℃. Copper alloy or aluminum alloy can be used for low-pressure and small-diameter valves. The valve body should be able to fully withstand the expansion and contraction caused by temperature changes, and the structure of the valve seat part will not be deformed due to temperature changes.