Back-up rings reduce the sealing gap between components and thus prevent damage to the seal due to gap extrusion. They are used together with O-rings as well as other sealing elements. Their use extends the service life of the seal. Back-up rings are used for higher pressures, pulsating pressures or larger sealing gaps. They are also used in the case of vibrations and higher speeds as well as higher operating temperatures and in cyclical applications.
Back-up rings can be manufactured serially in various profile geometries in PTFE, POM, PA and, for special applications, also in PEEK, PET, PCTFE, PTFE compounds, etc. Standard and special dimensions are also available in elastomer materials. In a concave design, the O-ring is centred in its installation position, and can thus be subjected to higher loads. A trapezoidal back-up ring design is chosen for higher pressure loads and larger sealing gaps. Back-up rings can also be supplied in a slotted design to facilitate installation.