PTFE back-up ring 8001011108

PTFE

When a part of an O-ring comes out of its groove and gets lodged in the gap between the two sealing elements, it is referred to as extrusion. This phenomenon compromises the seal and leads to rapid deterioration of the O-ring. In combination with an O-ring or an X-ring, Back-up rings are used to overcome the problem of extrusion under high pressure. The back-up ring is placed on the opposite side of the pressure applied to the seal. In cases where pressure is applied from both sides of the seal (double-acting), two back-up rings are placed on either side. This is a simple, fast, and effective solution to implement. Benefits and applications Extended lifespan of the O-ring Cost-effective solution with low sealing costs • Possibility to widen machining tolerance of grooves Resistance to pressures higher than that of the O-ring alone (recommended from 50 bar for any system) Back-up rings are used in systems with severe pressures or high risks of extrusion. Most often, they are associated with O-rings. 5 profiles of back-up rings Back-up ring T1: Spiral Back-up ring T2: ST8C (flat) with a 30° cut Back-up ring T3: ST8 (flat) Back-up ring T4: ST9C (concave) with a 30° cut Back-up ring T5: ST9 (concave) Manufacturing process Typically, elastomeric Back-up rings are obtained through moulding. However, upon request and for shorter lead times, Techné also offers machined parts. Plastic Back-up rings are obtained through machining. Materials The material choice is determined by the operating temperature, chemical resistance, and the hardness of the seal, which should be defined based on the application. The type of Back-up ring should be selected according to the applied pressure.