For high pressure applications it is common to use one or two back-up rings to prevent the O-ring from extruding out of the clearance gap on the low pressure side of a groove.
Back-up rings are typically made of a high grade engineering plastic, such as PTFE or PEEK. These higher modulus materials do not suffer the same visco-elastic extrusion mechanism as elastomers.
Backup rings can be supplied as solid rings or with scarf cuts to aid installation.
Visit the Precision Polymer Engineering Ltd website for more information on Back-up Rings