It is no surprise that the natural gas industry relies on cryogenic valves, as these operations often involve environments with temperatures as low as -150°C (-238°F). Cryogenic valves are specifically designed to ensure the safe storage of such gases. Furthermore, they are highly effective during transport, capable of operating efficiently at pressures up to 750 psi and temperatures as low as -196°C (-320°F).
There is a wide variety of cryogenic valves available in various specifications to accommodate different pressure ranges. Common types include ball valves, butterfly valves, solenoid valves, and double block and bleed (DBB) valves. Because cryogenic gases are highly sensitive, even an undetected leak can lead to catastrophic damage and significant hazards. Understanding the different types of cryogenic valves helps in selecting the right one for specific operating conditions.
Cryogenic Ball Valves
A ball valve features a spherical closure element with a central bore; when the valve is open, this bore aligns with the pipeline. These valves typically utilize polytetrafluoroethylene (PTFE) seats to ensure smooth operation. Key characteristics include:
- Efficient flow control: Low pressure drop and rapid opening/closing.
- Potential drawbacks: The sealing surfaces and the surface of the ball are prone to wear, which may affect long-term reliability.
Cryogenic ball valves are well-suited for applications requiring unobstructed flow, such as the large-scale transport of cryogenic liquids.
Cryogenic Butterfly Valves
Butterfly valves belong to the quarter-turn valve family and consist of a circular disc that rotates around a central axis. They are lightweight, compact, and highly versatile.
Features of butterfly valves include:
- Rapid operation: Opening or closing requires only a quarter-turn.
- Cost-effectiveness: Generally more affordable compared to other types of cryogenic valves.
- Shorter service life: Prone to wear during continuous use.
Cryogenic butterfly valves are frequently used in settings where weight and space are strictly limited, such as in pipelines or mobile cryogenic equipment.
Cryogenic Solenoid Valves
Cryogenic solenoid valves utilize an electromagnetic coil—activated or deactivated—to rapidly open or close the valve core. This enables remote on/off control of cryogenic media such as liquid nitrogen, liquid oxygen, and LNG. They serve as critical, high-speed shut-off components in cryogenic storage tanks, refueling systems, and air separation units.
Key optimizations compared to standard ambient-temperature solenoid valves include:
- Extended Bonnet: The valve stem is lengthened by 50–150 mm to create a thermal insulation buffer, preventing the transfer of extreme cold upward and ensuring that the coil and packing do not freeze or seize.
- Cryogenic-Resistant Materials: The valve body is constructed from 304/316L stainless steel and undergoes a cryogenic stress-relief process during manufacturing to eliminate the risk of brittle fracture at -196°C. Sealing components utilize modified PTFE or metal-to-metal hard seals, ensuring zero leakage even at ultra-low temperatures.
- Specialized Components: Springs are made from Inconel (a nickel-based alloy) to maintain stable elasticity at -196°C. The coils feature a waterproof, explosion-proof encapsulated design, with options available up to the ExdⅡCT6 rating for use in flammable or explosive environments.
Capable of providing zero-leakage shut-off for flammable, explosive, and cryogenic media, these valves are widely used in LNG receiving terminals, storage tanks, tanker trucks, and refueling stations—specifically within -162°C liquefied natural gas pipelines—as well as in the cryogenic separation of petrochemical off-gases and ethylene cryogenic processing units.
Cryogenic DBB Valves
Cryogenic Double Block and Bleed (DBB) ball valves are designed to provide dual isolation within a pipeline, with a dedicated bleed line to drain any fluid trapped between the two ball elements.
Design Features
- Valve Body Construction: Forged, bolted (two-piece or three-piece), or top-entry design.
- Seat Construction: Soft-seated or metal-seated; ball and seat surfaces undergo hardening treatment; modular/composite seat design.
- Single Piston Effect (SPE) / Double Piston Effect (DPE) sealing configurations.
Functional Characteristics
- Double Block and Bleed (DBB) design.
- Auxiliary seals made of pure graphite.
- Anti-static device.
- Blowout-proof stem design.
- Optional low-fugitive-emission stem packing.
- Combination of lip seals and graphite seals.
- Corrosion-Resistant Alloy (CRA) overlay available for all dynamic sealing areas or wetted parts.
- Optional extended bonnet.
Operation Methods
- Manual: Wrench or gear operator with locking mechanism.
- Actuated: Pneumatic, hydraulic, or electric.
Cryogenic DBB valves are typically used in bypass loops for instruments such as flowmeters or pressure gauges that require periodic calibration. This configuration allows for the isolation of upstream pressure, provides a secondary seal, and enables the venting of trapped pressure—facilitating the removal of instruments or allowing maintenance to be performed while the downstream side is depressurized.
This article outlines four common types of cryogenic valves and their applications. If you would like to learn more about cryogenic valves or are interested in purchasing high-quality cryogenic valves, please feel free to contact us. Our technical team is ready to assist you.
