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Ultra-low temperature forged steel ball valve application characteristics and design requirements

Low temperature forged steel ball valve characteristics and design requirements

Low temperature forged steel ball valves mainly refer to low temperature medium systems for mediums ranging from -196 degrees to 150 degrees. Forged steel low temperature valve bolted winding gasket and threaded joint all welded seal type, full diameter or reduced diameter, seal with pressure smooth hole (for gate valve, ball valve), integral upper seal seat, open rod bracket type , anti-static, self-centering plate pressing sleeve type.

The material that works at low temperature should ensure its low temperature performance, mainly to ensure its cold impact strength. The trim must be properly selected to have sufficient cold impact strength to prevent breakage. Alloy steels of C and Cr quickly lose their impact strength at temperatures below -20 ° C, so the use temperatures are limited to -30 ° C and -50 ° C, respectively. Nickel steel containing 3.5% Ni can be used at -100 ° C, and nickel steel containing 9% Ni can be used at -192 ° C. Austenitic stainless steel, nickel, monel, Hastelloy, titanium, aluminum alloy and bronze can be used at lower temperatures (-273 ° C). Shanghai Mingbao Valve Co., Ltd. reminds the selection of low temperature valve gaskets and packing materials. As the temperature is lowered, the amount of shrinkage of the fluoroplastic is large, which deteriorates the sealing performance and easily causes leakage. Asbestos packing cannot avoid osmotic leakage. Rubber has a swelling property for liquefied natural gas and cannot be used at low temperatures. In the design of low temperature valves, on the one hand, the structural design ensures that the packing is operated close to the ambient temperature.

Six requirements for low temperature forged steel ball valve design:

1. The valve should have the ability to work for a long time in low temperature medium and ambient temperature.

2, in order to be able to use at -196 ° C low temperature, the valve is generally designed as a long valve cover.

3. The valve assembly working at low temperature cannot be lubricated, so structural measures are needed to prevent the friction parts from being scratched.

4. The low temperature medium should not have harmful effects on the operation of the wheel and the sealing performance of the packing.

5. The valve assembly that is in direct contact with the low temperature medium shall have an explosion-proof and fireproof structure.

6. Valves should not be a significant source of heat for cryogenic systems. This is because the inflow of heat, in addition to reducing the thermal efficiency, such as excessive inflow, will also cause the internal fluid to evaporate rapidly, causing abnormal pressure rise, posing a hazard.

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