Cryogenic valves work under harsh conditions, most of the working medium for the flammable, explosive, permeable substances, the lowest working temperature up to -269 ℃, the highest use of pressure up to 10MPa. Therefore, the design, manufacture and inspection of cryogenic valves and general valves compared to a big difference. In general, according to the use of low-temperature valves, the design of the following requirements:
1) the valve and its components in the low-temperature media and the surrounding ambient temperature should have the ability to work for a long time (generally 10 years or 3500 ~ 5000 cycles);
2) valve relative to the low-temperature medium, should not be a significant heat source, this is because the inflow of heat will reduce the thermal efficiency, and the inflow of heat is too much, but also may make the valve inside the low-temperature medium vaporisation, resulting in an abnormal pressure rise, resulting in danger;
3) The cryogenic medium should not have a deleterious effect on the operating performance of the handwheel and the sealing performance of the packing;
4) direct contact with cryogenic media and the structure of the valve assembly should meet the relevant explosion-proof and fire prevention requirements;
5) in the low-temperature state of the valve assembly can not be lubricated, so you need to take measures to prevent the friction parts are scratched.
The above requirements should be throughout the design process of cryogenic valves, in addition, it should be noted that the above requirements are unique to cryogenic valves, cryogenic valves in the design process should also comply with the relevant general valve requirements.