Backup Ring

Back-up Rings or anti-extrusion rings are thin rings that are that are designed to prevent O-Ring extrusion under pressure. They fit in the gland between the seal and the clearance gaps to provide zero clearance. These are used when the fitting clearance between the sealing surface of the O-Rings is large enough to allow the O-rings to extrude all certain working pressure. A number of materials can be used for Back-up rings , but PTFE has the benefit of a very low friction in dynamic applications.