O-Ring Failure Modes: Heat Hardening & Oxidation Damage

June 09, 2020

O-Ring Failure Modes

While O-ring designs are meant to withstand outside influences within the application environment in which they are used, failure is still possible. A combination of factors, from design to human error, can contribute to the premature failure of an O-ring.

As a technical resource for our customers, we wanted to share our knowledge and experience with potential seal failures and how you can prevent them. Our series highlights some of the most common O-ring failure modes.

Heat Hardening & Oxidation Damage

Hardening and oxidation occur when the part is exposed to high temperatures for an extended period of time, causing plasticizer volatilization and oxidative cracking. As the O-ring material hardens, the O-ring is unable to retain sealability, causing leakage and failure to occur.

When the temperature in or around a system is considerably heightened, the seals are more likely to fail. Lubricants and plasticizers are more susceptible to volatilization and thus the seal becomes less flexible. Continuous exposure to elevated temperatures most frequently results in permanent compression set (seal deformation, see video below), resulting in loss of seal memory and sealing force retention.

Forms of Excessive Heat Damage


The material hardens, diminishing O-ring flexibility, limiting its ability to retain sealability, especially in dynamic applications.

Plasticizer Volatilization

When the plasticizers are volatilized, the O-ring shrinks and is unable to retain sealability within the sealing groove.

Oxidative Cracking

Cracks or pits begin to form on the O-ring surfaces most exposed to high temperatures. Cracks and pits on the seal surfaces are points of initiation for leakage to occur.

Compression Set

Continuous exposure to heat causes permanent compressed deformation of the O-ring, resulting in loss of sealing force and eventual leakage (see video below).


Failure Prevention

To prevent seal failures caused by heat hardening and oxidation damage from occurring, there are a couple things that can be done, such as:

  • Using a suitable high-temperature resistant elastomeric material
  • Limiting O-ring exposure to air (oxygen)
  • Lowering the operating temperature of the system

At Zatkoff Seals & Packings, we offer a variety of customized solutions to solve challenging sealing applications. We are committed to offering innovative solutions that deliver high quality results. Contact us to get in touch with a technical sales representative.

This is part of a series of educational articles to aid in understanding common O-ring field failures. Click here to read additional articles in the series.


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