Why Energising Springs Are More Complex Than They Look

The energising spring is often the smallest component within a seal assembly, but it is also one of the most highly stressed. Despite its size, the spring has a significant influence on sealing performance, reliability and service life. 

In simple terms, the energising spring makes the seal seal. However, its role extends far beyond applying force. The spring geometry, material and specification all affect how much load is applied, how consistently that load is maintained, and how the seal performs as wear occurs over time. 

If an energising spring is incorrectly specified, the result isn’t usually immediate failure. More often, it is a gradual decline in performance: increased leakage, shortened maintenance intervals, reduced efficiency and unnecessary replacement costs. These issues are frequently accepted as normal wear.  The reality, however, is that an alternative spring design may have delivered a significantly better outcome. 

One of the most important factors is spring geometry. Different spring types produce very different load-deflection characteristics. 

Garter springs remain the most widely used option and provide a proven, economical solution for many applications. 

Helical springs offer high loads in compact spaces, making them suitable where sealing forces are high and available deflection is limited. 

Meander (cantilever) springs provide greater working deflection and are particularly effective in dynamic sealing applications. 

Canted coil springs offer a unique advantage. Their geometry creates a near-constant force profile throughout their working range, meaning sealing force remains consistent as wear occurs. This allows seals to be specified for long-term operating performance rather than simply their installation condition. In some valve applications, a single canted coil spring can also replace multiple compression springs. 

Material selection is also important. While stainless steels remain suitable for many applications, demanding environments may require specialist alloys such as Inconel, Monel, Hastelloy/Phynox or Elgiloy. Factors including temperature, corrosion resistance, fatigue performance, magnetic properties and regulatory requirements all influence the final specification. 

Spring failure is typically driven by four key factors: high temperatures, low temperatures, corrosion and fatigue. Understanding the operating environment and selecting the appropriate spring geometry and material are essential for maximising service life. 

At Clifford Springs we don't expect engineers to become spring specialists, but we know that a good understanding of how spring geometry, material selection and operating conditions influence performance make it easier to identify the most suitable spring type and material for each application.

Check out an extended version of this article at: https://www.cliffordsprings.com/choosing-the-right-energising-spring-for-seals/

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