CRYOGENIC BALL VALVE

USAGE
The cryogenic ball valve is used to cut off or connect the media in various pipelines of Class150～Class1500. The valves made of different materials are suitable for various media and different temperature. The lowest working temperature is -196℃. The driving modes include manual operation, worm and worm gear transmission, pneumatic operation and electric operation. The connection ends can be flange or welding.
PRODUCT RANGE
The cryogenic ball valves are calssified into cryogenic floating ball valves and cryogenic trunnion ball valves. Refer to the data of floating ball valve and trunnion ball valve for the product range, face-to-face dimensions, connection flange dimensions and etc. For the ball valves with temperature higher than -50℃, the long neck structure is not designed. For the ball valves with temperature lower than -50℃, the neck length is generally designed according to standard requirements or according to user requirements.

STRUCTRUAL FEATURES
The cryogenic ball valve is used for low temperature service condition, especially the dangerous media service conditions such as natural gas. Our company has accumulated rich experience in designing, manufacturing, testing and inspecting the cryogenic ball valve.
Material Selection
Common steel will show low temperature brittleness under low temperature. Therefore, it is a key for design and manufacturing to select suitable body materials according to the lowest working temperature of the cryogenic ball 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 must be subjected to cryogenic treatment after rough machining. The ball and seat sealing face should be subjected to cryogenic treatment hare alloy spray welding/overlay welding. Then grinding and assembly an be carried out, so as to ensure the adaptability of materials under low temperature. In addition, the pacing, gasket, bolt and nut shall be made of materials suitable for low temperature service condition.

Structural Design And Machining And Manufacturing Features
According to standard requirements, the ball valves with temperature lower than -50℃ generally adopts the long neck structure design to improve the temperature at the packing and ensure reliable sealing of stem packing. The neck length is generally designed according to standard requirements or according to contact requirements if users have special requirements.
For the valve used for low temperature media, when the valve is at the closed position, the low temperature liquid staying in the middle cavity of valve will be gasified with the rise of temperature, which causes the volume to expand rapidly and leads to abnormal pressure rise in the middle cavity, or even valve breakage if serious. The ball vale is provided with the function of middle cavity automatic pressure relief. In case of abnormal pressure rise in the middle cavity, the medium in the middle cavity will overcome the spring pre-tightening effect through its own force and push the seat out of the ball to realize automatic pressure relief, so as to ensure valve safety.
According to contract requirements, cryogenic test can be carried out to test operating torque, sealing performance and other indexes under low temperature.
The parts of the valve have been subjected to cryogenic treatment to ensure stability of form and size of parts under low temperature.