Cryogenic LNG Spring Energized Seals
Gallagher's Spring Energized Seals
Deep Dive into Spring Energized Seals
LNG Operating Environment: What Makes it Different
Liquefied Natural Gas presents one of the most demanding sealing environments encountered in industrial service. While often grouped under the broader category of “cryogenic applications,” LNG service introduces a unique combination of extreme temperature, light-gas behavior, and thermal cycling that exposes the limitations of many conventional sealing approaches.
Common Seal Failure Modes in LNG Service
Most LNG seal failures are not sudden or catastrophic—they are predictable outcomes of mismatched materials, insufficient preload, or incomplete consideration of cryogenic behavior. Understanding these failure modes is essential to selecting the right sealing solution.
Why Spring-Energized Seals Are Used in LNG
The defining challenge of LNG sealing is maintaining reliable contact force at cryogenic temperatures, independent of pressure and material elasticity. This is the core reason spring-energized seals are widely used in LNG service.
Seal Jacket Material Selection for LNG
Material selection for LNG seals is often misunderstood as the primary determinant of performance. In reality, jacket material plays a supporting role, enabling the spring to function effectively under cryogenic conditions.
Spring Selection for LNG Applications
The performance of a spring-energized seal in LNG service is driven as much by spring design as by seal jacket material. At cryogenic temperatures, the spring becomes the primary source of sealing energy, responsible for maintaining contact force as polymers stiffen and hardware contracts.
Gland Design for Cryogenic LNG Sealing
Even the most robust spring-energized seal will fail if installed in an improperly designed gland. LNG service magnifies the effects of poor gland geometry, surface defects, and thermal mismatch.
Surface Finish & Hardware Requirements for LNG Service
In LNG applications, sealing performance is often limited not by the seal itself, but by the condition and geometry of the mating hardware. Cryogenic temperatures amplify the impact of surface imperfections, making surface finish and hardware preparation critical to achieving gas-tight sealing.
Static vs Dynamic LNG Sealing Considerations
While LNG systems contain both static and dynamic seals, the distinction between the two is often less clear than in ambient-temperature equipment. Many LNG components experience long static dwell periods punctuated by infrequent motion. Seals must be designed to perform well under these conditions.
Installing & Commissioning for LNG Seals
Proper installation and commissioning practices are essential to achieving reliable sealing in LNG service. Errors introduced during installation may not become apparent until the system is cooled down, making early stage diligence critical.
Thermo-Mechanical Performance of Spring-Energized Polymer Seals in Cryogenic LNG Transfer Systems
This case study examines the development of spring-energized polymer face seals engineered for LNG transfer and tank systems operating at cryogenic temperatures approaching −320 °F. Traditional elastomer seals struggle in these environments due to thermal contraction, embrittlement, and loss of sealing force, so the project focused on combining advanced PTFE-based seal jackets with a constant-force metallic spring to maintain reliable contact stress independent of temperature.