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Features of low temperature valve
- Mar 08, 2018 -

Cryogenic valves, as the name implies, is able to work in cryogenic low temperature. As the delimitation of its working temperature, usually we call cryogenic valves with the working temperature lower than 40, which are mainly used for liquefied gas, separation, transmission and storage devices. The working temperature can reach -270 . Cryogenic valves mainly include gate valve, globe valve, check valve, ball valve, butterfly valve and throttle valve type etc.

 

In recent years, the cryogenic valves are used more and more widely, become one of the indispensable important equipment of oil chemical industry, air separation, gas industry. The media is not only in low working temperature, but also toxic or flammable and explosive, and with strong permeability. Thus it determines high standard of the materials and design of valves and other special requirements. It is not only required to work at the set temperature, but also to ensure the performance at normal temperature.

 

Compared to normal temperature valves, low temperature valves request higher stem and packing, which is to reduce the heat coming from the outside, ensure that the temperature of the stuffing box stays at over 0 that the packing can work normally, prevent frosting or freezing of the stem in the stuffing box and the upper part of the bonnet.

 

Long neck cover design mainly refers to the design of the neck length L, the distance from the bottom of the stuffing box to the surface of the seal seat. It has connection to the coefficient of thermal conductivity, thermal conductivity material area and the surface coefficient of heat transfer, heat dissipation area of factors, generally obtained by experimental method. When the temperature is higher than -100 , you can choose ferritic stainless steel. When the temperature is lower than -100 , you can choose austenitic stainless steel. Valves with low pressure and small diameter can choose copper alloy or aluminum alloy. The body should be able to bare the expansion and contraction caused by temperature change, and temperature changes will not cause permanent deformation of the seat.

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