LNG & Cryogenic Sealing Solutions
PTFE and spring-energised seals for liquefied natural gas, liquid nitrogen and ultra-low temperature industrial processes.
Cryogenic sealing presents a unique challenge: no standard elastomer remains flexible below approximately -60°C. At LNG temperatures (-162°C) or liquid nitrogen temperatures (-196°C), rubber O-rings harden, crack and leak almost instantly. For these applications, PTFE is the only practical sealing material. However, because PTFE lacks elastic recovery, cryogenic seals almost always use spring-energised PTFE designs. A stainless steel or Inconel spring applies continuous radial force, maintaining seal contact as the PTFE jacket contracts in the cold. We supply solid PTFE O-rings for static face seals and spring-energised PTFE seals for valves, flanges, LNG loading arms, and cryogenic pumps. All designs are validated for thermal cycling and low-temperature leakage.
Application Requirements
Recommended Materials
Design Tips
- 1.Never specify elastomer O-rings for service below -60°C
- 2.Use spring-energised PTFE for any application requiring reliable sealing at cryogenic temperatures
- 3.Design grooves to accommodate thermal contraction of both PTFE and metal housing
- 4.Surface finish should be Ra ≤ 0.4 μm for static PTFE seals
- 5.Specify anti-static PTFE grades for oxygen-rich or explosive gas environments
Common Sizes
| Size | Typical Use |
|---|---|
| Standard AS568 cross-sections for static cryogenic O-rings | General application |
| Custom PTFE rings for large-diameter LNG flanges | up to 2,000 mm |
| Spring-energised seals for valve stems and ball-valve seats | General application |
| LNG transfer swivel and loading arm seals to customer drawing | General application |
Frequently Asked Questions
Can rubber O-rings be used for LNG?
No. All standard elastomers become glassy and lose sealing force below approximately -60°C. LNG service at -162°C requires PTFE or metal seals.
What is a spring-energised PTFE seal?
It is a PTFE seal jacket backed by a metal spring (stainless steel or Inconel). The spring provides the elastic force that PTFE lacks, maintaining seal contact through extreme temperature cycles.
Is PTFE safe for liquid oxygen service?
Yes. Virgin PTFE is compatible with liquid oxygen (-183°C). For oxygen-enriched environments, anti-static or carbon-filled PTFE is recommended to prevent static discharge.
What is the largest cryogenic seal you can manufacture?
We regularly produce large-diameter PTFE rings and spring-energised seals up to 2,000 mm for LNG flanges and cryogenic vessels. Larger sizes are available on request.
Request a custom quote
Request a cryogenic sealing quote with PTFE specification