Rules of Thumb

Rising Temperatures and O-Ring Failure

Industrial zone, Steel pipelines, valves and gauges

Temperature is one of many factors to consider when selecting the best o-ring material for a given application. Rising temperatures can have a variety of negative impacts on the efficacy of a seal. For example, prolonged exposure to heat degrades o-ring materials physically and chemically. Excessive heat is also known to cause o-ring materials to swell and become inflexible. Why does this happen and how can it be prevented?

What does high temperature do to o-rings?

Exposing o-ring elastomers to high temperatures can cause physical and chemical deterioration. When exposed to extremely high temperatures, o-rings soften and swell within their gland, causing increased friction in dynamic applications. This means that an o-ring made of materials with poor resistance to heat are more likely to fail over time.

Another factor to consider is pressure. High pressure applications are especially prone to failure because room temperature tests in such applications may be unreliable. If these tests do not adequately account for high temperatures, irreversible chemical changes may occur over time, increasing seal hardness and causing compression set and volumetric changes.

Best high temperature choices

A number of special compounds have been developed to provide dependable o-ring sealing performance in high temperature situations. These include:

  • Fluorocarbon (VT)
  • Silicone (SL)
  • Fluorosilicone (FS)

These compounds feature heat resistance to at least 400°F, with some reaching up to  600°F for short periods. An additional number of o-ring materials feature temperature resistance to 300°F, with special resistances to particular fluids or environmental factors. For example, ethylene propylene offers high resistance to steam.

Finding high temperature options

For help sourcing o-rings with excellent resistance to heat or other factors present in your application, consult our material selection guide. Note that this tool is meant to be used as a professional guide only. Because no two situations or installations are the same, the comments, suggestions, and recommendations it generates are meant to be general and should not be relied on without independent verification based on your particular installation or use. We strongly recommend that the seal you select be rigorously tested in your actual application prior to production use.

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