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Back-up rings are plastic or rubber rings used to prevent the O-ring from entering the clearance gap. When high pressures are exerted on the O-ring, its soft rubber material can be forced into the clearance gap causing the O-ring to extrude (see our O-ring brochure for examples of O-ring failure). The hard back-up ring material will keep the O-ring material from flowing into the gap which will prevent premature failure. Plastic Back-up rings come in cut styles 27595, 28774, 28782, which follow the respective MIL specifications.

Our KasPex™ PEEK MP39 compound is ideal material for back-up rings due to the compound’s high pressure and high temperature capabilities. Additional back-up ring materials include other KasPex™ PEEK compounds, PTFE, fluorocarbon/Viton™, and nitrile.

* Back-up rings can generally be selected based on O-Ring dash numbers. See the O-Ring section of our website for dash number dimensions.

Product Profiles
Solid Flat (27595) Scarf Cut (28774) Spiral Cut (28782) Solid Contoured Butt Cut