Spring-Energised Metal Seals
Spring-energised metal seals, also referred to as spring-energized metal seals or spring-loaded metal seals, are high-performance static sealing solutions designed for high-temperature, high-pressure, vacuum and demanding industrial applications where conventional elastomeric seals may not provide the required performance. The seal incorporates a resilient metallic spring element designed to maintain sealing load against the mating surfaces. This spring action allows the seal to accommodate changes in joint conditions caused by temperature cycling, pressure fluctuations, thermal expansion and mechanical movement.
International Seal supplies standard and custom spring-energised metal seals in stainless steels, nickel-based superalloys and specialist metals. Seals can be supplied to customer drawings, existing specifications or application requirements, with different profiles, materials, spring characteristics and surface coatings available.
Spring-Energised Metal Seals and Spring-Energised PTFE Seals
The term “spring-energised seal” covers two distinct product families, and the difference matters when specifying.
A spring-energised PTFE or polymer seal uses a metallic spring to load a PTFE or polymer jacket against the sealing surfaces. The spring supplies the force; the jacket does the sealing. These are widely used as dynamic rod, piston and rotary seals, and their temperature and chemical limits are set by the jacket material.
A spring-energised metal seal has no polymer element. The sealing surfaces are metal, and a resilient metallic spring structure maintains the load that holds them against the mating faces. These are static seals, and because every component is metallic they are specified where temperature, radiation, vacuum or media conditions rule out a polymer jacket altogether.
This page covers spring-energised metal seals. If your application calls for a spring-energised PTFE seal, see our PTFE seals and components range. If you are not sure which is appropriate, send us the operating conditions and whether the joint is static or dynamic, and we will advise.
Spring-Energised Metal Seal Specifications
Spring-energised metal seals are engineered for critical static sealing applications where reliable sealing force must be maintained across demanding operating conditions.
- Resilient Spring-Energised Metal Construction
- High Springback & Recovery
- Stainless Steel & Nickel-Based Alloy Options
- High-Temperature & High-Pressure Applications
- Vacuum & High-Vacuum Applications
- Surface Platings & Coatings Available
- Supplied to Drawings or Application Requirements
Materials & Surface Coatings
Spring-energised metal seals are available in a range of stainless steels, nickel-based superalloys and specialist materials. Material selection should consider operating temperature, pressure, process media, corrosion resistance, thermal cycling and the mechanical requirements of the sealing system.
Spring-energised metal seals can be supplied with a range of specialist surface platings and coatings to improve sealing performance, surface conformity and corrosion resistance.
Depending on the application, available options include silver, gold, copper, nickel, tin, PTFE-based coatings and specialist plating combinations. Selection should consider the base alloy, spring material, operating temperature, pressure, available seating load and mating surface finish.
For further information, see our Metal Seal Platings and Coatings section.
Spring Material and Material Condition
A spring-energised metal seal has two material decisions rather than one: the alloy of the sealing element, and the alloy of the spring. The spring has to retain its load-bearing properties throughout the operating range, so its material is often selected independently of the seal body — nickel-based alloys are commonly used where spring characteristics must be maintained at elevated temperature.
The condition in which each alloy is supplied, whether work-hardened, age-hardened or annealed, also affects the sealing load generated and the recovery retained by the seal. Where a drawing or existing specification calls for particular alloys or conditions, include them with your enquiry so the correct seal is quoted. For additional guidance, see our Metal Seal Materials & Coatings Guide.
Typical Applications
Spring-energised metal seals are particularly suited to applications where sealing performance must be maintained despite significant changes in temperature, pressure or joint movement. The resilient spring element provides continuous sealing load, making these seals suitable for critical equipment operating beyond the practical limits of many conventional elastomeric sealing materials.
- Aerospace & Defence Equipment
- High-Pressure Flanges & Connections
- High-Temperature Process Equipment
- Vacuum & High-Vacuum Systems
- Turbines, Engines & Exhaust Systems
- Valves, Pumps & Compressors
- Chemical & Petrochemical Processing
- Power Generation & Energy Systems
- Pressure Vessels & Critical Static Joints
The correct spring-energised seal design, material and surface coating should be selected according to the operating temperature, pressure differential, flange movement, mating surface finish, process media and required leakage performance.
How Spring-Energised Metal Seals Work
Spring-energised metal seals use the elastic properties of a metallic spring element to generate and maintain contact pressure against the sealing surfaces.
When the seal is installed, compression of the spring structure produces the initial sealing load. The spring can then respond to dimensional changes within the joint, helping maintain sealing contact as operating conditions vary.
This combination of controlled compression, resilience and springback makes spring-energised metal seals particularly useful in systems exposed to repeated thermal or pressure cycles.
High-Temperature Spring-Energised Seals
At elevated temperatures, mating components can expand and contract as equipment moves through operating and shutdown cycles.
Spring-energised metal seals are designed to accommodate this movement while maintaining controlled sealing force. High-temperature alloys can be selected where mechanical strength and spring characteristics must be maintained under elevated operating temperatures. These designs are commonly considered for turbines, engines, exhaust systems, aerospace equipment and high-temperature process machinery.
High-Pressure & Vacuum Sealing
Spring-energised metal seals are also suitable for high-pressure and vacuum applications where controlled sealing load and low leakage performance are important.
The seal geometry, spring characteristics, base material and surface coating can be selected around the pressure differential and specific design of the sealing joint. For critical applications, flange condition, surface finish and installation load should be considered alongside the seal specification.
Spring-Energised Metal C-Rings and Other Profiles
Spring energisation can be incorporated into several metallic sealing profiles rather than being a sealing profile in its own right. One commonly specified design is the spring-energised metal C-ring, in which a metallic spring is fitted inside the open C-section to provide sealing load independently of system pressure. These designs can be supplied in internal and external pressure configurations, depending on the application. For further information, see our Metal C-Rings page.
Spring-energised designs are chosen over purely pressure-energised ones where:
- System pressure is low, variable, or absent during part of the duty cycle
- Sealing must be maintained through start-up, shutdown and pressure-relief conditions
- A consistent and higher sealing load is required than the section alone would deliver
- The joint moves repeatedly through thermal cycles and the spring can follow that movement
The trade-off is that a spring-energised design generally requires a higher seating load and offers less recovery than the equivalent pressure-energised seal, so the clamping load available at the joint should be established before specifying one. Where a joint moves substantially but clamping load is limited, a metal E-ring may be the better route. See our metal seals overview for a comparison of metallic sealing profiles.
Custom Spring-Energised Metal Seals
Spring-energised metal seals can be supplied for applications requiring specific diameters, cross-sections, spring characteristics, materials and surface treatments.
International Seal can support requirements based on new applications, customer drawings, existing specifications and replacement components.
For new or replacement applications, information including seal dimensions, operating temperature, pressure, media, flange design and existing drawings can be reviewed to help determine an appropriate sealing solution.
Spring-Energised Metal Seal FAQs
What is a spring-energised metal seal?
A static metallic seal containing a resilient metallic spring element that maintains sealing load against the mating faces. Because the load comes from the spring rather than from system pressure, sealing force stays consistent as pressure varies and as the joint moves through thermal cycles.
What is the difference between a spring-energised metal seal and a spring-energised PTFE seal?
A spring-energised PTFE seal uses a metallic spring to load a PTFE or polymer jacket, and is commonly used as a dynamic seal with limits set by the jacket material. A spring-energised metal seal has metal sealing surfaces throughout and is a static seal, specified where a polymer jacket would not survive the conditions.
What is the difference between spring-energised and pressure-energised metal seals?
A pressure-energised seal relies on system pressure entering the open section to increase sealing force as pressure rises. A spring-energised seal generates load from an internal spring regardless of system pressure. Spring energisation suits low, variable or intermittent pressure; pressure energisation suits consistently pressurised joints and generally needs less seating load.
Is "spring energized" the same as "spring energised"?
Yes — the same product. “Spring energised” is the British spelling and “spring energized” the American. You may also see spring-loaded metal seals used for the same components.
Can spring-energised metal seals be used at high temperature?
They are commonly specified for high-temperature duties including turbines, engines, exhaust systems and high-temperature process machinery, where the spring accommodates expansion and contraction through operating and shutdown cycles. Capability depends on the alloys, material condition and coating selected, so send us the operating temperature and we will confirm what can be supplied.
Can you supply spring-energised metal seals to a drawing?
Yes. Spring-energised metal seals can be manufactured to customer drawings, dimensions or application requirements across a range of diameters, cross-sections, spring characteristics, alloys and surface treatments. Existing drawings, part numbers and physical samples can be reviewed where a replacement or alternative is needed.
Need a Spring-Energised Metal Seal Quote?
Send us the seal or groove dimensions, operating temperature and pressure, direction of pressure, expected joint movement, process media and quantity where known, and we will confirm the seal design, alloys and surface coating that suit the application.
Drawings, manufacturer part numbers, photographs and physical samples can all be reviewed. If the duty would be better served by a pressure-energised C-ring or an E-ring, we will tell you.