Product description of Cryogenic Ball Valve
Cryogenic forged steel ball valve is mainly used in low temperature medium systems with medium at -196-150 degrees. The bolt connection, spiral wound sealing gasket and threaded connection of forged steel low-temperature valve are all welded sealing type, full diameter or reduced diameter, the seal is equipped with pressure stable hole (for gate valve and ball valve), the integral upper seal seat, rising stem support type, anti-static, self centering pressure plate compression sleeve type.
The material working at low temperature should ensure its low temperature performance, mainly to ensure its cold impact strength. The valve internals shall be properly selected to have sufficient cold impact strength to prevent fracture. The impact strength of C and Cr alloy steel will soon lose when it is lower than -20 ℃, so the service temperature is limited to -30 ℃ and -50 ℃ respectively. Nickel steel containing 3.5% Ni can be used to -100 ℃, and nickel steel containing 9% Ni can be used to -192 ℃. Austenitic stainless steel, nickel, Monel alloy, Hastelloy, titanium, aluminum alloy and bronze can be used at lower temperatures (-273 ℃). Attention should also be paid to the selection of gasket and packing materials for low temperature valves. As the temperature decreases, fluoroplastics shrink a lot, which will reduce the sealing performance and easily cause leakage. Asbestos filler cannot avoid leakage of permeability. Rubber has foaming property to liquefied natural gas and cannot be used at low temperature. In the design of low temperature valve, on the one hand, the structural design ensures that the packing works at a temperature close to the ambient temperature.
Features of Cryogenic Ball Valve
1. The valve shall be able to work for a long time under low temperature medium and ambient temperature.
2. In order to be used at a low temperature of -196 ℃, the valve is generally designed as an extended bonnet.
3. The valve assembly working at low temperature cannot be lubricated, so structural measures need to be taken to prevent friction parts from scratching.
4. Low temperature medium shall not have harmful effects on handwheel operation and packing sealing performance.
5. Valve assemblies directly in contact with low-temperature media shall have explosion-proof and fire-proof structures.
6. The valve should not become a significant heat source of the low temperature system. This is because the inflow of heat not only reduces the thermal efficiency, but also causes rapid evaporation of internal fluid if too much inflow, resulting in abnormal pressure rise and danger.