by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Spring-Energized Seals for the Fluid Industry

Spring-energized seals have proven themselves indispensable in the fluid handling industry, alongside pumps, valves, fittings, and filtration. In fact, they serve as a precision technology to support key fluid handling systems. Canted coil springs enhance reliability, efficiency, and service life in fluid handling applications by providing precise force control, robust sealing, and long-term performance.

What Are Spring-Energized Seals? 

Spring-energized seals may look like ordinary polymer seals from the outside, but the difference lies within. A metallic spring is built into the seal, and its purpose is to maintain continuous contact between the sealing lip and the mating surface. That spring ensures the seal maintains the right amount of contact pressure, even when conditions fluctuate.

The design gives engineers a reliable way to handle problems that defeat traditional seals. Under pressure cycling, thermal changes, or material creep, ordinary seals can lose their ability to press tightly against surfaces. Once that happens, leaks are inevitable. With a spring-energized design, however, the spring compensates for those changes. It provides a consistent, repeatable load that keeps the sealing interface intact.

These seals are also highly versatile. Spring-energized seal jackets can be manufactured with advanced polymers such as PTFE, PEEK, or UHMW-PE. Engineering polymers such as this resist heat, wear, and chemicals. Combined with the spring element, they deliver performance that elastomeric seals or standard designs simply cannot match. The result is longer service life, reliable operation, and the ability to thrive in environments where ordinary seals fail.

In industries where precision is critical—fluid handling, aerospace, medical, and energy—spring-energized seals stand out as a proven choice. They bridge the gap between demanding operating conditions and the need for dependable, leak-free performance.

Why the Fluid Handling Industry Needs Advanced Spring Technology 

There are four key challenges in the fluid handling industry that can be addressed through the use of advanced spring-energized seal technology. These include large pressure fluctuations, exposure to aggressive chemicals, high cycling rates, and extreme temperature swings.

Large Pressure Fluctuations

When pressure inside a pump or valve spikes, a conventional elastomeric seal can lose preload. Eventually, they will deform, relax, and eventually fail to maintain a consistent sealing force. The result? Leaks and unpredictable system behavior. Spring-energized seals, by contrast, maintain nearly constant force across wide deflection ranges. Their unique geometry keeps seals energized and couplings secure, even when pressure swings from one extreme to the other.

Exposure to Aggressive Chemicals

Elastomers and some polymers will swell or crack when they encounter solvents, caustics, or sterilizing fluids. Once degradation sets in, seals fail quickly. Spring-energized seals solve that problem with corrosion-resistant alloys like stainless steel, Inconel, and Hastelloy. Pair canted coil springs with PTFE or PEEK seal jackets, and you have a system that resists attack and stays reliable, even in the harshest chemical environments.

High Cycling Rates

Pumps, valves, and quick disconnect couplings cycle millions of times in their lifetime. Standard seals suffer from fatigue, creep, and inconsistent force output long before those cycles are reached. That inconsistency leads to premature wear or outright leakage. Spring-energized seals are built differently. Their geometry spreads stresses evenly, allowing spring-energized seals to withstand high cycle counts while delivering the same force from start to finish.

Extreme Temperature Swings

Temperature changes wreak havoc on seals. Elastomers turn brittle in the cold, soften in the heat, and lose elasticity under cycling. Spring-energized polymer seals can continue to perform across cryogenic lows and elevated highs. Whether in sterilization cycles, hot fluid transport, or cryogenic handling, canted coil springs can keep seals energized and predictable.

The Takeaway

Every one of these challenges comes back to the same requirement: consistent, predictable seal force. Traditional approaches fall short, but spring energizers deliver the durability, adaptability, and precision needed to keep fluid handling systems running smoothly.

Applications in the Fluid Handling Industry

There are a host of applications for spring-energized seals in the fluid handling industry, starting with pumps and valves where they ensure long-lasting seals, both for static and dynamic applications. They are also very valuable in quick-connect/disconnect couplings, where they provide both secure retention and controlled release. In filtration systems, spring-energizers help to maintain seal integrity during pressure surges. These sealing solutions are also ideal for use with medical and pharmaceutical fluid handling, where there are FDA-compliant sealing solutions that can endure aggressive sterilization and cleaning processes. Finally, these seals are ideal for oil & gas fluid systems that operate under extreme temperatures and pressures in both topside and downhole equipment.

Conclusion

Robust, reliable sealing is absolutely necessary in fluid handling operations, regardless of the industry. Spring-energized seals for the fluid industry provide robust, reliable seals. They can address large pressure fluctuations, exposure to aggressive chemicals, high cycling rates, and extreme temperature changes. 

If you are designing a sealing solution for a fluid handling operation, contact us today at Advanced EMC to learn how spring-energized seals can positively impact the reliability and life of your system. Our engineers look forward to working with you.

by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Designing Polymer Seals for Dynamic Applications: Balancing Wear, Friction, and Thermal Expansion

Designing polymer seals for dynamic applications can be a challenging task. Polymer seals have proven vital in dynamic applications such as rotary shafts, reciprocating pistons, and oscillating systems. However, dynamic conditions can introduce challenges that are not found in static conditions. These challenges include continuous motion, heat buildup, wear mechanisms, and variable pressures.

This blog post examines three key challenges involved in dynamic sealing: wear, friction, and thermal expansion.

The Role of Polymers in Dynamic Seals

Engineering polymers such as PTFE and PEEK offer several advantages over both traditional metals and elastomeric seals in dynamic systems. Such benefits include outstanding performance even in operating environments that include extreme temperatures and require excellent chemical compatibility and extremely low friction. And engineers can further enhance the most desirable features of these polymers through the use of fillers and blends (e.g., graphite, carbon, bronze, glass, and even PTFE).  Polymer seals are also lightweight and ideal for compact systems where space is limited.

Balancing Wear Resistance

One of the most limiting factors in dynamic seal applications is wear. The three most common wear mechanisms involved are adhesion, abrasion, and fatigue. 

  • Adhesive wear happens when the seal momentarily sticks to the counterface, thus tearing material away from the surface and resulting in material transfer or scoring.
  • Abrasive wear occurs when hard (abrasive) particles or rough surfaces cut into the polymer, creating grooves and accelerating material loss.
  • Fatigue wear takes place when the seal is subject to repeated cyclic stresses that form micro-cracks, eventually leading to surface flaking or spalling.

Polymers can effectively address wear issues. PTFE effectively combines extremely low dynamic friction and excellent self-lubrication. This combination makes it well-suited for high-wear dynamic applications such as piston rings in gas compressors. Another example is the use of PEEK seals in aerospace actuators, where its high resistance and ability to maintain mechanical strength at high temperatures make it an excellent choice for applications involving cycling under high loads.

One of the most effective ways to further improve the wear resistance of PTFE and PEEK dynamic seals would be the use of filled composites, the use of appropriate surface finishes on countersurfaces, and wise design choices that minimize localized stresses.

Managing Friction

Friction is particularly problematic in dynamic seals, as it leads to heat generation, energy loss, and accelerated degradation. This problem leads to a trade-off between achieving an effective sealing force and maintaining low friction. 

PTFE is an excellent example of how low-friction engineering polymers can help achieve this balance. PTFE has the lowest coefficient of friction of any engineering polymer, and is far less than that of metal or elastomers. Its self-lubricating nature keeps friction very low at the shaft-seal interface, which will minimize heat buildup and lost energy. In fact, it can even reduce energy loss during dry running conditions. The strength and modulus of elasticity of PTFE can be modified through the use of fillers and hybrids.

Spring-energized seals, which use a metallic energizer to keep the seal lip in contact with the sealing surface and generate a predictable, consistent load to compensate for problems such as wear, thermal expansion, and pressure changes. As the load is kept within a predictable range, the friction is also kept at consistent levels over a well-distributed sealing force.

Thermal Expansion Considerations

Polymers indeed possess a higher coefficient of thermal expansion when compared to metals and most elastomers. Changes in dimensions can impact clearance, sealing performance, and contact pressure in dynamic sealing applications. In aerospace and automotive applications, for example,  there can be an abundance of extreme temperature cycling, which is going to be especially problematic in rotary shaft seal designs. 

There are several approaches to minimizing the impact of thermal expansion, starting with customized PTFE or PEEK polymer blends with materials that will lower the coefficient of thermal expansion without compromising wear resistance or friction.

The use of spring-energized seals allows the polymeric sealing lip to remain in contact with the sealing surface despite changes in geometry or alignment, whether they are due to wear, thermal expansion, or thermal contraction in the presence of extreme temperature cycling. 

Note that both of these approaches can be further enhanced through predictive modeling of how the seal will deform under thermal stress.

Polymer Seals for Dynamic Applications: Design Best Practices

Here are some straightforward design best practices related to dynamic sealing challenges:

  • Always match the seal geometry to motion type (i.e., rotary vs reciprocating).
  • Carefully consider the allowable surface roughness and hardness of mating surfaces.
  • Respect the PV limit (pressure × velocity) when selecting a polymer.
  • Remember the importance of predictive modeling (finite element analysis for thermal and tribological performance).
  • Always test under real-world operating conditions before full-scale deployment.

Conclusion

Dynamic sealing requires balancing wear, friction, and thermal expansion, with no single solution that fits all. Fortunately, advances in polymer science and composites make it possible to design seals that meet increasingly demanding requirements. However, engineers must still carefully match polymer formulations, energizers, and geometries to the unique conditions of each application.

If you need a dynamic seal for an application, contact the experts at Advanced EMC. Our engineers are very experienced and highly knowledgeable, able to take you all the way from seal design and material selection to testing.