• SPECIAL TOPIC: SEVERE SERVICE •
Detail-Driven Approaches for Reliability in Harsh Environments
Explore the different designs and materials of cryogenic valves that are capable of withstanding extreme temperatures and liquefied gases in various applications.
• By Bernard Horsfield
Cryogenic valves play a critical role in industries that handle liquefied gases such as LNG, liquid oxygen, nitrogen, hydrogen, and helium. These valves must withstand extreme temperatures, typically below-150 ° C(-238 ° F), without failure.
Selecting and engineering the right cryogenic valve is essential for safety, reliability, and long-term performance. This article explores key design considerations, material selection, common challenges, and best practices in cryogenic valve engineering.
1. Key Design Considerations Cryogenic valves must operate reliably under conditions where conventional valve designs would fail. At extremely low temperatures, materials contract and can become brittle, which makes careful material selection paramount.
Thermal cycling poses a significant risk to materials and could cause leakage. As a result, effective design methods are critical to performance. To minimize heat transfer and ensure proper stem function, extended bonnets are essential; drip collars and waterproof insulation are also important since they help reduce frost and ice formation that would otherwise impair valve performance. Additionally, a good cryogenic valve has the lowest operating torque possible to prevent excessive mechanical stress during use.
Cryogenic valves must operate reliably under conditions where conventional valve designs would fail, including at extremely low temperatures.
2. Material Selection for Cryogenic Valves
Material performance changes dramatically at cryogenic temperatures. Many common metals become brittle and prone to cracking, which leads to failures. Proper material selection is critical. For example, carbon steel cannot be used as it becomes brittle and unreliable at cryogenic temperatures, making it unsuitable for applications below-30 ° C(-22 ° F)
3. Common Challenges in Cryogenic Valve Engineering
3.1 Brittle Fracture Risk Metals become more brittle at cryogenic temperatures due to reduced atomic mobility and increased stress concentration. Materials including stainless steel, nickel alloys, and aluminium offer more toughness at low temperatures.
3.2 Seat and Seal Performance Elastomeric and polymer seats can harden and crack( depending on the design) at cryogenic temperatures, leading to leakage. Common seat materials include:
• Filled Polytetrafluoroethylene( PTFE or Teflon): Polytetrafluoroethylene has low friction and reliable chemical resistance, but it shrinks at cryogenic temperatures and is only suitable for small valves.
• Polyether Ether Ketone( PEEK): Polyether Ether Ketone has higher strength and durability. However, it is more costly and doesn’ t efficiently manage shock loading( physical or temperature).
Proper material selection is critical as material performance changes dramatically at cryogenic temperatures.
20 Valve World Americas | November 2025 | www. valve-world-americas. com