Gaskets,also called back-up rings,it is used as a supportive components that are made by materials that are resistant to extrusion under pressure.
When installed in a recess along with elastomeric sealing components like o-rings and seals, the back-up ring's function as protective elements preventing the elastomeric material of the sealing component from extruding into the sealing gap under pressure. The cross section of a back-up ring is generally rectangular, and they are not designed for sealing purposes.
Back-up rings are used in external and internal sealing applications, as in piston seals and rod seals. Material can be PTFE,POM,NBR,VITON,PEEK,PCTFE,UHMWPE,etc.
BOSS Sealing Solutions' gaskets also include bonded seal(copper plating dowty seal and zine plating bonded seal).