O-Ring Failure Modes: Spiral Failure

July 21, 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.

Spiral Twist Failure

Spiral twist failure is often found on long stroke, hydraulic piston seals. It’s rare, yet possible, for spiral twist failures to occur on rod seals.

Spiral twist failures occur when one segment of an O-ring slides across the mating surface, while another segment adheres and rolls into a spiral twist configuration. At a single point on the perimeter, the O-ring remains trapped in the spiral twist and may leak or maintain a seal. However, eventually the O-ring will likely break.

Contributing Factors

  • Eccentric components
  • Wide clearance combined with side loads
  • Uneven surface finishes
  • Inadequate lubrication
  • Excessively low O-ring material hardness
  • Lagging stroke speeds
  • Improper installation

A spiral twist failure pattern can be observed when the O-ring appears to have been cut halfway through the cross section. A spiral-shaped pattern will exhibit a series of deep 45-degree angled cuts.

Potential Solutions

Looking for a solution? Try one or more of the following:

  • Check for an out-of-round cylinder bore
  • Decrease clearance gap
  • Machine metal surfaces to 10-20 micro-inch finishes
  • Consider internally-lubed O-rings for improved lubrication
  • Increase O-ring material hardness and/or cross section
  • Employ anti-extrusion back-up rings

Extensive testing and qualification is recommended before use in the field to prevent these failures from occurring.

At Zatkoff Seals & Packings, we are committed to offering the best sealing solutions for our customers. Contact us to see how we can customize our products for your unique application.

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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