Cryogenic ball valves are used in air separation plants, LNG storage, distribution and transportation, aerospace, petrochemical and medical industries. Under extremely low temperatures and in the harshest of environments, Cryogenic ball valves need to consistently exhibit high flow capacity, tight shutoff, energy efficiency and long service-free life.
Design Features:
These valves are required to be operated to offer assured leakage rates. Valves which are recommended to use below -50⁰C are designed with an extended bonnet which separates the operator and stem seal from the cold temperature.
When the valve is at the closed position, the low temperature liquid trapped in the middle cavity of valve is subject to gasification in case of abnormal temperature rise, causing the rapid volume expansion and pressure rise inside the cavity, which could lead to valve damage and severe accident. Kolink Cryogenic Ball Valve is designed unidirectional with vent holes in both the stem slot and the upstream face of the ball, preventing the rising pressure from being trapped in the valve. Each valve is marked with a flow direction arrow to prevent incorrect installation.
Stem primary seal and bearing are located near the packing end of the extended stem to keep these parts from the low temperatures and providing a blow-out proof stem design. The live-loaded stem packing that provides self-adjustment to the stem packing is included at the top of the extension. Valves are specially cleaned to remove all grease and oils that may react with the service media.
Cryogenic ball valves are available in floating or trunnion mounted ball and in side-entry or top-entry body design. Seat and gasket materials are designed and selected in order to meet the most demanding requirements of leak rate and fugitive emission. The valve body made of different materials are suitable for various different temperature. With high density seats and seals throughout, Kolink cryogenic ball valve is able to work under -196°C.
Material Selection:
Common steel shows cold brittleness under low temperature. It is critical to select body materials to suit the working temperature of the valve. Refer to the following table for the lowest working temperature of body materials. The low temperature materials shall be subjected to low temperature impact test according to standard requirements.
For valves with working temperature lower than -100℃, the body, bonnet and stem, ball and seat are required of cryogenic treatment after rough machining, and the packing, gasket, bolt and nut shall also be made of materials suitable for low temperature condition.
According to contract requirements, cryogenic test can be carried out to test operating torque, sealing performance and other indexes under low temperature.
Structural Design And Machining And Manufacturing Features
Features of Cryogenic Ball Valves:
- Extended bonnet
- Vent holes on stem and ball
- Unidirectional flow
- Vent holes in stem and ball for pressure release
- Live-loaded stem packing
- Degrease Operation
- Low Temperature material options
- Fire Safe to API 607
- Antistatic Device
- Anti-blowout Stem
- Gear Operation or Actuator Available
- Optional Low emission packing according to ISO 15848
Applicable Standards of Cryogenic ball valves:
- Design & Manufacture: API 6D, BS 5351, API 608, ISO 17292, MSS SP-72
- Fire-safe: API 607, API 6FA
- Face to Face: API B16.10, API 6D, EN 558, DIN 3202
- End Connection: ASME B16.5, EN 1092, JIS B2220, ASME B16.25
- Test and Inspection: API 6D, EN 12266, API 598
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