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Back-up Rings

backringsWhat is a Back-up Ring Used For?

The function of Back-up rings is to provide added resistance to the risk of extruding a seal into gaps in its housing when under pressure. Back up Rings, sometimes also called Anti-Extrusion Rings or backing rings, are not designed to have any sealing function in their own right, they are simply there to support the actual sealing elements of a design and stop them extruding under higher pressures.

Back-up Rings Styles, Sizes and Materials

For the reasons mentioned above, Anti-Extrusion Rings can be contoured or flat, depending on the design requirements of the sealing system. They can come in the form of a solid ring, a split ring or even a spiral back up ring, depending on the environment that the Back Up Ring is expected to operate in, and for ease of fitting. We stock standard spiral Back-up rings to BS5106 and manufacture solid Back-up rings in a variety of profiles and materials , such as neoprene, nitrile, EPDM, silicone and PTFE, depending on the requirements of the application. BS5106 also gives guidance on suitable housing designs.

Choosing the Correct Back-up Ring

Extrusion under pressure can happen to almost any type of seal, so these Back up Rings are placed behind the seal if it is a single acting system, or both sides if double acting. The Anti-Extrusion Rings are always made of a harder material than the seal itself, to minimize the amount of extrusion of the seal into the sealing gap of the seal housing, by supporting the sealing element itself with a close fit to the housing.

When greater sealing and system forces are anticipated, the more precise the fit of the parts must be. Consideration always needs to be given to the environment expected for any particular seal and its back-up rings, and the degree of friction losses acceptable, in order to provide the most suitable solution.

View our standard profiles for general guidance on our complete range of Back Up Rings; you will find our standard Back-up profiles listed as ST108, ST109, ST110, ST111, ST112 and ST113 all of which conform to BS 5106:1988 (R07). These styles can be rapid manufactured in a variety of different materials and sizes depending on the application and we also stock standard products for immediate shipment.

Please contact us so that we may advise on the best solution for your application for your specific requirements.

ST108 Back-Up Ring Seal

ST108 Back-Up Ring SealThe ST108 Back-Up Ring Seal reduces the possibility of extruding a seal into gaps in its housing when put under pressure. This particular backing ring conforms to:

BS 5106:1988 (R07)

ST109 Back-Up Ring Seal

The ST109 Contoured Back-Up Ring Seal supports the sealing elements of a design in order to prevent them from extruding under increased pressures. This anti-extrusion ring conforms to:

BS 5106:1988 (R07)

ST110 Back-Up Ring Seal

The ST110 Angled Back-Up Ring Seal (Outer) are not designed to have any sealing function, but are simply there to provide support to the actual sealing elements of a design. This type of back up ring conforms to:

BS 5106:1988 (R07)

Other Back-Up Ring Seals

ST111 Angled Back-Up Ring Seal (Inner)

ST111

Angled Back-Up Ring Seal (Inner)

ST112 Triangular Back-Up Ring Seal (Outer)

ST112

Triangular Back-Up Ring Seal (Outer)

ST113 Triangular Back-Up Ring Seal (Inner)

ST113

Triangular Back-Up Ring Seal (Inner)

Back Up or Anti Extrusion Ring profile range from Martins Rubber. Available in a range of materials and sizes

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