Anti-Extrusion Rings

Posted on January 30, 2020 James Williams Anti-Extrusion Rings

O-rings are in use throughout many aircraft and operate as an important sealer whenever they are applied. However, while acting as a sealant, o-rings are susceptible to extrusion and failure. To prevent this, many o-rings in are coupled with an anti-extrusion ring. Anti-extrusion rings are designed and manufactured to act as supplemental support and guarantee the seal performance of an o-ring. Sometimes called back-up rings, an anti-extrusion ring is an inflexible ring that holds an elastomeric seal in its correct shape and place. Anti-extrusion are necessary in a variety of situations. Some of their applications include:

  • Where low-endurance o-rings are installed
  • Where undesirable mechanical circumstances are inevitable
  • Dynamic applications exceeding 100 bar
  • Static applications exceeding 950 bar
  • Hydraulic cylinders
  • High-pressure hydraulic systems and high-pressure valves
            There are three types of Polytetrafluoroethylene (PTFE) anti-extrusion rings: solid, single turn, and spiral cut. Solid PTFE rings can be extremely difficult to install. Depending on the configuration and intended application, the PTFE may not be elastic enough, and the ring must be repaired after it is installed to bring it back to its original dimensions. Single turn and spiral cut rings avoid this issue thanks to their flexibility. Both can be opened slightly during the installation process without permanently damaging them. It is important to note that, while single turn and solid anti-extrusion rings are capable of withstanding tension during installation, all types of rings are prone to damage and should be installed with care.
            Before selecting an anti-extrusion ring, it’s important to be aware of specifications such as the inner dimension of the ring/outer dimension of the shaft, the radial cross-section of the elastomer, and the ring’s thickness. Anti-extrusion rings are created from a firmer, more rigid material than a typical o-ring. Despite this, they are elastic enough to alter their shape under stress, thereby closing the extrusion gap. O-ring grooves are enlarged when they are manufactured with the expectation that they will also contain an anti-extrusion ring.
At Aerospace Purchasing, owned and operated by ASAP Semiconductor, we can help you find all the anti-extrusion parts for the aerospace, civil aviation, and defense industries. We’re always available and ready to help you find all the parts and equipment you need, 24/7-365. For a quick and competitive quote, email us at or call us at 1-412-212-0606.

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