Back-up Rings

Examples of our stock:

• P.T.F.E. (Teflon®) Spiral Back-Up rings
• P.T.F.E (Teflon®) Single Turn Back-Up rings
• P.T.F.E (Teflon®) Solid Back-Up rings
• P.C.T.F.E and P.T.F.E (Teflon®) Contoured Back-Up rings

Description

Back-up rings, are protective and supporting elements made from extrusion-resistant materials which generally have a rectangular cross section. Back-up rings have no intended sealing function.
They are installed in a groove together with an elastomeric sealing element preferably with a corresponding o-ring in static applications. Due to the tight fit of the Back-up ring in the housing, they prevent extrusion of the pressurised elastomeric sealing element into the sealing gap.
The back-up ring may be machined concave on one side, to better accommodate the o-ring and retain shape under high pulsating pressure.

Materials

Back-up rings are as standard manufactured in cut or uncut designs, from virgin PTFE. In view of the unfavourable cold flow behaviour of virgin PTFE, these back-up rings are used only for low to medium loads.
For higher load requirements, filled PTFE materials (with glass fibre, bronze, carbon, etc.) have to be used. For sealing against high pressures, Back-up Rings made from specially modified thermoplastic materials are used.
For the series production of larger quantities, injection moulded back-up rings can be manufactured, e.g. NBR 90 Shore A, FKM90 Shore A, or thermoplastic elastomers (TPE) on request.