• SPECIAL TOPIC: SEVERE SERVICE •
These valves must undergo low-temperature testing to verify functionality and leakage performance in constant extreme environments.
• Metal Seated Valves: These are used where extreme conditions require durability( cryogenic). These are typically fitted with a‘ non-metallic’ seal for bubble tight shutoff.
3.3. Thermal Expansion & Contraction Cryogenic valves undergo significant dimensional changes during cooldown and warm-up cycles, which can create several operational challenges. Shrinking seals may result in both seat and stem leakage, while differential expansion can cause components to loosen. Typically, in triple offset valves, disc and seat misalignment can further compromise performance.
Warm-up cycles may pose safety concerns, particularly when trapped media expands within the system, producing devastating pressures. It must be noted that whilst a lot of calculations can give an‘ indication,’ actual R & D through testing is the only tangible way to check and analyse any design.
4. Best Practices for Cryogenic Valve Design & Selection
4.1. Use Extended Bonnets Cryogenic valves usually include extended bonnets to distance the packing from the cold zone, preventing stem freezing and leakage. These originate from the Shell cryogenic standards and exist as‘ cold box’ or‘ non-cold box’ lengths. Drip plates also need to be included to stop icing.
4.2. Choose Proper Stem Seals Graphite packing withstands extreme temperatures but may leak over time. But another reason graphite is chosen is fire safety.
Bellows seals provide a more robust solution by preventing gas leakage through stem packing. They also indicate a warning of leakage.
4.3. Conduct Cryogenic Testing Cryogenic testing is an extremely dangerous and expensive process. But cryogenic valves must undergo low-temperature testing to verify functionality and leakage performance. This is because copying or replicating another cryogenic valve doesn’ t automatically mean it will work.
Common tests include:
• Helium Leak Testing – Ensures zero leakage under extreme cold.
• Liquid Nitrogen Testing – Simulates real-world conditions.
• Thermal Cycling Tests – Measures performance under repeated expansion / contraction.
LNG valves are difficult to test at the temperatures they will be used at, but liquid Nitrogen( LiN) can be utilized as the closest media capable of providing stable environments.
All tests are performed back to front, especially for liquid service. The liquid exists on the outside while gas is on the inside.
4.4. Use Proper Actuation Systems
• Manual Valves – These valves require long extensions for gearboxes, which require low-torque operation to avoid freezing issues.
• Pneumatic & Electric Actuators – Pneumatic & electric actuators must use low-temperature lubricants and materials.
• Hydraulic Actuators – Hydraulic actuators are generally avoided in cryogenic services due to fluid viscosity changes.
5. Industry Applications of Cryogenic Valves Include
• LNG Transport & Storage – Tankers, terminals, pipelines.
• Industrial Gas Processing – Oxygen, nitrogen, hydrogen handling.
• Aerospace & Rocket Fuel Systems – Liquid oxygen( LOX) and liquid hydrogen( LH 2
).
• Medical & Scientific Applications – MRI machines, particle accelerators.
Conclusion Cryogenic valve selection and design both demand a deep understanding of low-temperature materials, sealing technologies, and thermal effects. Proper material selection, extended bonnets, and rigorous testing are key to ensure long-term performance and safety. By following best practices, end users can minimize risks and optimize reliability in extreme environments. •
• ABOUT THE EXPERT •
Bernard Horsfield’ s experience in valves and controls spans more than 35 years, during which he has held numerous engineering and sales positions. He now leads Rodefish Ltd., which specializes primarily in triple offset valves, while also bringing extensive expertise in ball, butterfly, and control valves.
Valve World Americas | November 2025 | www. valve-world-americas. com 21