Sealing Shielding

Diagnosing a Damaged O-Ring

diagnosing a damaged o-ring, failed o-ring, failure mode, chewed up o-ring, gland overfill, damaged seal, compression set, wear ring, extrusion, thermal expansion, chemical swellSeveral O-ring failure modes look the same, and identifying the right root cause is critical to solving the problem. Here are a few lessons learned from some real world applications.

The most common failure mode we see is the flattened O-ring. When a customer sent me a picture of a flattened O-ring, they were looking for a more compression set resistant material. However, when we took the O-ring out of the groove, the bottom side was still perfectly round. This was actually a wear problem caused by a rough surface finish. This is the key to telling them apart, but you have to take the O-ring out of the groove to see it.

  • Compression set causes the O-ring to flatten on both sides.
  • Wear causes the O-ring to flatten on one side only.

Other common failure modes

Another common failure mode that a customer had was a chewed up O-ring, but they weren’t running at a high enough pressure to really cause extrusion.

In this case, the O-ring was extruding in both directions which told us that they had a gland overfill problem. They simply had too much O-ring in the groove. Keep in mind that thermal expansion can cause this, especially when dealing with perfluoronated elastomers.You can also see gland overfill caused by severe chemical swell, but this will also cause the O-ring to get soft and gummy.



For more information on failure modes, check out our Leak Troubleshooting app found on the Parker O-Ring Division Support Page.

It's what you don't see that makes it a Parker O-ring. Be sure and bookmark our always-up-to-date online interactive O-Ring eHandbook.


Dan Ewing, O-Ring Division, Business Development Engineer



Article contributed by Dan Ewing, Business Development Engineer, Parker's O-Ring Division.




For related content:

Proper Installation of an O-Ring: Standard Male Gland

Proper Installation of an O-Ring: Standard Female Gland 

Proper Installation of an O-Ring: Face Seal Gland

Proper Installation of an O-Ring: Full and Half Dovetails

How to Lubricate an O-Ring

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Comments for Diagnosing a Damaged O-Ring

Good morning. Can you help me. I Have perpendicular small cracks on the o-ring. it's possible to determining the cause please.
Thank and Regards

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