The cryogenic ball valve is a valve device designed for extremely low temperature environments. The medium flow control is achieved by rotating the ball 90 degrees. The applicable temperature range is -40℃ to -196℃, and some models can adapt to ultra-low temperature conditions of -196℃. Its core design is optimized for the characteristics of cryogenic media to ensure sealing and operational reliability. It is widely used in industrial fields such as liquefied natural gas (LNG), liquid oxygen, and liquid nitrogen.
1. Structural design
Long-neck bonnet structure
The extended valve neck design is adopted to isolate the stuffing box from the cryogenic medium to avoid the freezing and failure of the stuffing. The neck length of some models can reach 250mm to adapt to different working conditions.
Anti-abnormal boost mechanism
The valve body integrates a pressure relief channel or bypass structure to prevent the sudden pressure increase caused by the volume expansion after the cryogenic medium is vaporized, ensuring the safety of the system.
Sealing system
The ball and the valve seat sealing surface are welded with hard alloy, and the spring preload is combined to achieve stable sealing at low temperature.
Some models adopt a combination structure of metal seal and PTFE soft seal to adapt to temperature fluctuations and medium flushing.
2. Materials and Processes
Main Material
The valve body is made of LCB, LC3 low-temperature steel or stainless steel (such as CF8, CF8M), and the ball is mostly made of F304/F316 stainless steel to ensure low-temperature toughness and brittle crack resistance.
Special Process
Key components need to be cryogenically treated before finishing (immersed in liquid nitrogen to -192℃ and cycled twice) to eliminate the risk of low-temperature shrinkage and deformation.
The surface of the valve stem is chrome-plated or nitrided to enhance wear resistance and sealing reliability.
3. Performance Characteristics
Zero Leakage Seal
Through the precision-machined ball and valve seat, the leakage is ≤2ml/min·DN, which meets the safety requirements of flammable and explosive media.
Wide Range Adaptability
The working pressure covers 1.6MPa to 42MPa, and the corrosion resistance meets the NACE MR0175 standard. The applicable media include LNG, liquid hydrogen, etc.
Operational Convenience
Supports manual, pneumatic, and electric drive, and some patented designs integrate visual opening indication and quick maintenance structure.
4. Classification and application
Type subdivision
Floating type: Relying on the medium pressure to push the ball to press the valve seat, the structure is compact and suitable for small-diameter pipelines.
Fixed type: The ball is fixed by the upper and lower pivots, with smaller torque, suitable for large-diameter high-pressure scenarios above DN50.
Typical application scenarios
Mainly used for liquefied natural gas storage and transportation, air separation equipment, petrochemical tail gas treatment and aerospace fuel systems to solve the risk of medium phase change expansion.
