The temperatures involved with LNG happens to be at the point where many elastomers and polymer materials lose elasticity and begin to behave as brittle materials. Some seals may also experience dimensional fluctuations related to temperature changes, further increasing the likelihood of failure. If temperature fluctuations are periodic, problems related to cyclic stress will arise. Another issue related to dynamic sealing at cryogenic temperature is lubrication: standard lubrication solutions do not work at such low temperatures.

The choice of sealing is limited to UHMW or PTFE Polymers and a full contact anti shrinkage spring is essential.

Both seal jacket materials can be specified as PTFE, usually known as Teflon or Flourolon 1000. Ultra high molecular weight PE or UHMW, Fluorolon 5000 can handle low temperatures involved in low-temperature services without becoming brittle (some levels can handle temperatures as low as -350 ° F) or succumb quickly to the effects of cyclical stress. In addition, both UHMW and PTFE are self-lubricating, low-friction, dry operating supports, and are non stick/sliding materials. Moreover, both materials are compatible with various chemicals,  including those that may be encountered in LNG plants.

Spring energized seal is a sealing assembly that includes an energizing spring. With appropriate spring force and system fluid pressure, the sealing lip (face) is pushed out and gently pressed against the metal surface being sealed to generate excellent sealing effect. The actuation effect of the spring can overcome slight eccentricity of the metal mating surface and wear of the sealing lip, while maintaining the expected sealing performance. This sealing design, when combined with PTFE lips, has been found ideal for cryogenic applications involving LNG. The spring energizer adds permanent elasticity to the seal, compensating for lip wear, eccentricity, hardware misalignment, and (perhaps the most important) extreme pressure and dimensional changes when using in LNG.

The sealing ring is made of sealing materials with good cryogenic temperatures resistance, which can be applied to the vast majority of cryogenic temperature chemical fluids and solvents. Its low swelling ability allows for long-term sealing performance. Various special springs are used to overcome the elasticity problem of cryogenic temperature of 200 degrees, and sealing components that can replace the vast majority of static or dynamic applications (reciprocating or rotating motion) are developed.

The recommended geometry for the spring energizer is a simple helical spring when cryogenic temperatures and either static, reciprocating, or rotary motion are involved.  Springs can be selected from Hastelloy, 304/316 stainless steel, Inconel, or Elgiloy according to different usage environments, and undergo low-temperature resistance treatment, making them suitable for various low-temperature corrosive fluids.