Backup Rings

KOK backup rings are manufactured to customer drawing specifications for use in conjunction with O-rings in high-pressure sealing systems.

In pressurized applications, elastomeric O-rings may deform into the clearance gap between mating components. Excessive extrusion can result in permanent deformation, edge nibbling, and premature seal failure. Backup rings provide mechanical support to the O-ring, restricting extrusion and maintaining seal stability under elevated pressure conditions.

Design Function

Extrusion behavior depends on:

• System pressure
• Clearance gap
• O-ring hardness
• Temperature
• Dynamic vs. static conditions

Backup rings act as a rigid support element, reducing the risk of seal damage when system pressures exceed the extrusion resistance of the elastomer alone.

Configurations

KOK manufactures backup rings according to customer design, including:

• Solid (uncut) rings
• Split (scarf-cut) rings
• Spiral rings

Configuration selection depends on installation method, groove geometry, and pressure direction (single- or double-acting systems).

Material Options

• PTFE (broad chemical compatibility, low friction)
• Polyamide (high mechanical strength and wear resistance)

Material selection is typically defined by system requirements and application environment.

KOK produces backup rings in accordance with specified dimensional tolerances and material grades to ensure consistent integration within existing seal groove designs.

For manufacturing inquiries or drawing review, please contact our engineering team.