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Temperature vs Pressure: The Double Challenge for PTFE Spring Seals

 

In the world of advanced sealing solutions, PTFE spring seals have become the go-to choice for industries requiring durability, chemical resistance, and low friction. However, one of the biggest engineering challenges lies in managing the dual demands of extreme temperatures and high pressures—two conditions that often coexist in critical applications like aerospace systems, hydraulic cylinders, semiconductor processing, and hydrogen fuel technologies.

In this article, we’ll explore why temperature and pressure represent the "double challenge" for PTFE spring-energized seals, how these forces impact performance, and what design considerations are critical to ensure sealing integrity in such environments. We'll also highlight how Parjet's proprietary approach to material selection, spring design, and precision manufacturing provides a solution trusted by clients in over 30 countries.

 

Understanding PTFE Spring-Energized Seals

A PTFE spring seal, as known as Teflon spring seal, consists of a U-shaped jacket made of PTFE or a PTFE-based compound, energized by a metal spring—commonly a cantilever spring, helical spring, or canted coil spring—which maintains sealing pressure against mating surfaces. These seals are widely used in dynamic applications where shaft movement, media compatibility, and system performance are critical.

The spring energizer inside the seal compensates for jacket wear, thermal expansion, pressure deformation, and hardware misalignment. This allows PTFE spring seals to maintain a consistent load and prevent leakage even under severe operating conditions.

But what happens when these seals are subjected to both extreme heat or cold and significant pressure at the same time?

 

The Temperature Challenge

PTFE (Polytetrafluoroethylene) is known for its wide temperature tolerance—ranging from -200°C to +260°C, depending on the grade. However, temperature fluctuations affect both the seal jacket and the metal spring, often in different ways.

Key Issues at High Temperatures:

• - Thermal Expansion: PTFE expands significantly with temperature. If not properly accounted for, this can result in loss of seal contact pressure or even extrusion under pressure.
• - Spring Relaxation: At elevated temperatures, springs made of standard stainless steel may lose their elasticity, reducing energizer effectiveness.
• - Creep and Deformation: Under prolonged stress and heat, PTFE may exhibit cold flow, especially in unsupported areas.

Key Issues at Low Temperatures:

• - Loss of Flexibility: PTFE becomes more brittle at cryogenic temperatures, increasing the risk of cracking during installation or operation.
• - Reduced Spring Deflection: Springs may stiffen at sub-zero conditions, leading to uneven sealing or leakage.
• - Thermal Shock: Rapid changes in temperature can compromise the seal interface, especially if the jacket material and spring expand or contract at different rates.

 

The Pressure Challenge

While standard PTFE lip seals are suitable for low-pressure systems (typically under 0.5 bar), many industrial environments require sealing under pressures exceeding 10, 20, or even 30 bar—particularly in hydraulic pumps, compressors, and gas-handling equipment.

Common Pressure-Induced Failures:

• - Seal Extrusion: High internal pressure may cause the PTFE jacket to extrude into the hardware clearance gaps, particularly if the gland design is inadequate.
• - Blowout Risk: Without the correct spring load, high pressure can force the seal out of its groove.
• - Deformation of Seal Profile: Sustained pressure compresses the jacket over time, potentially altering the lip geometry and diminishing sealing performance.
• - Dynamic Friction Increase: Higher pressure increases the contact force and friction, which can accelerate wear if not carefully managed.

 

How Temperature and Pressure Interact

When temperature and pressure challenges coexist, their interaction multiplies risk. For example:

• - At high temperatures, high pressure accelerates creep, which can lead to seal deformation and leak paths.
• - In cryogenic systems, vacuum pressures amplify contraction effects, potentially breaking seal contact entirely.
• - At elevated pressures, thermal cycling can rapidly degrade spring performance if the wrong alloy is selected.

This is why selecting the correct combination of spring type, material, and PTFE compound is critical.

 

Parjet’s Engineering Approach to the Double Challenge

At Parjet, our HiPerSeal^® series of spring-energized seals are specifically engineered to combat the twin pressures of temperature and pressure extremes. Here’s how:

1. Advanced PTFE Compounds

Parjet formulates in-house PTFE blends using fillers such as glass fiber, carbon, or bronze, to improve mechanical strength, reduce creep, and enhance wear resistance across temperature ranges. This is critical for applications like hydrogen compression, semiconductor production, and cryogenic pumps.

2. Spring Material Customization

We offer springs in Elgiloy®, Hastelloy®, 301/316 stainless steel, and Inconel®—selected based on thermal and pressure fatigue profiles. This enables precise spring performance across -200°C to 300°C and up to 30 bar pressures.

3. Design Simulation with FEA

Our engineering team utilizes Finite Element Analysis (FEA) to simulate material behavior under complex operating loads. We analyze seal deflection, spring stress, and extrusion risk to optimize each design.

4. CNC Machining Precision

With over 10 CNC seal lathes in our ISO 9001 and IATF 16949-certified facility, we ensure micron-level accuracy in seal groove tolerances, essential for handling pressure without blowout or misalignment.

5. One-Stop Vertical Manufacturing

Unlike many seal providers, Parjet controls the entire production process—from PTFE powder compounding and tube extrusion to seal machining and spring welding—ensuring material traceability and consistent quality.

 

When Should You Choose a Spring-Energized PTFE Seal?

If your application involves:

• -> Wide temperature fluctuations (cryogenic to 250°C+)
• -> High or vacuum pressure sealing
• -> Chemical compatibility challenges
• -> Friction-sensitive components
• -> High shaft speed or slow dynamic motion
• -> Complex groove geometries or gland tolerances

…then a PTFE spring seal is likely the best solution.

 

Conclusion: Sealing Performance Is Not One-Dimensional

Too many seal failures occur because engineers focus on either temperature or pressure, but not both. The truth is, these two forces act simultaneously, and often unpredictably.

At Parjet, we don’t offer generic solutions—we engineer application-specific PTFE spring seals designed to conquer the challenges your system faces. From high-performance helical springs for vacuum to canted coil springs for low-friction valves, our HiPerSeal® technology ensures sealing reliability across the harshest environments.

Need help with a difficult sealing project?
Contact Parjet today for a consultation. Our engineers are ready to design a PTFE spring-energized seal that’s pressure-tested, temperature-proven, and made to last.