Cryogenic Valve is valve suitable for service that temperature -46 °C ~ -196 °C, , these valves are generally used extended-stem or extended-bonnet design.
The reasons to use used extended-stem or extended-bonnet design:
(1) The extended-stem has the function of protecting the stuffing box of the cryogenic valve, because the tightness of the stuffing box is one of the keys of the cryogenic valve. If the packing box leaks, it reduces the cooling effect and cause the liquefied gas to vaporize. As a result of media leakage, ice is formed on the filler and the stem, affecting the normal operation of the stem and simultaneously moving the stem up and down. Filler scratches, causing serious leaks. Therefore, need to ensure that the temperature of the stuffing box is under 8°C.
(2) The extended-stem or extended-bonnet structure facilitates the jacketing material of gryogenic valve and prevents the loss of cold energy of cryogenic valves.
(3) The extended-stem or extended-bonnet structure of cryogenic valve facilitates rapid replacement of the valve main part. Because the process piping and valves in the cold section of the equipment are often installed in the 'cold box', the valve cover can extend through the 'cold box' wall. When replacing a valve main part, it only to remove valve part through the valve cover without disassembling the valve body. The valve body and the pipe are welded together, and the leakage of the cold box is reduced as much as possible to ensure the sealing of the valve.
Zhejiang Zhengfeng Valve.