O-Ring Failure Modes: Explosive Decompression

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 new series will highlight some of the most common O-ring failure modes.

Explosive Decompression (ED) or Rapid Gas Decompression (RGD)

In this piece, we highlight explosive decompression, including causes, signs and symptoms, resolutions, and prevention tactics.

When an O-ring is under high-pressure gas for an extended period of time, and that pressure is reduced too rapidly, this type of failure can occur. The gas that gets trapped or absorbed in the O-ring’s micropores causes splits or ruptures (embolisms) in the surface of the O-ring.

This failure mode, called explosive decompression, is marked by random short splits or ruptures going deep into the O-ring’s cross section. Though not always noticeable, the surface may sometimes be covered with small blisters or pits.

Depending on their severity, these splits or ruptures can cause anywhere from minimal damage to total failure.

Failure Prevention

How can you prevent or minimize the risk of explosive decompression? The following are the most effective approaches:

• Increase the time for decompression, reducing the pressure more slowly.
• Increase the material hardness to a 80-95 durometer range.
• Increase the material formulation to achieve high modulus and high tear strength.
• Change the groove design to above 90% fill, being careful not to overfill.
• Replace the O-ring with a smaller cross-section O-ring.
• Use an explosive decompression-resistant O-ring elastomer, such as:
  • N1231-80
  • KB163-90
  • P4300A90
  • VG109-90
  • VG286-80
  • VX365-90
  • V1238-95
  • V1041-85
  • FF202-90
• Under very high pressure applications, consider utilizing a metal seal.

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.