Product
Backup Rings (Anti-Extrusion Rings)
PTFE, PEEK or elastomeric rings installed alongside an O-ring in the gland to prevent extrusion into the clearance gap at high pressure or elevated temperature.
PTFE back-up rings, stacked and ready for dispatch.
Overview
What it is
A backup ring is not itself a seal — it's a ring of hard, extrusion-resistant material fitted on the low-pressure side of an O-ring or X-ring to close off the clearance gap between the two mating parts.
Under high pressure, an elastomer seal will slowly flow (extrude) into the clearance gap between the housing and the shaft or piston, eventually nibbling away at the seal until it fails. A backup ring physically blocks that gap, giving the elastomer seal nowhere to extrude into, which lets the same seal run at a higher pressure or wider clearance than it could on its own.
Why use it
Key benefits
- Extends the pressure and temperature range of the primary seal
- Available in single-turn (scarf-cut), spiral (multi-turn) and solid (uncut) configurations
- Fits the same AS568/metric groove as the O-ring it supports
- Can be fitted on one or both sides of the seal depending on whether pressure is one-directional or bi-directional
Materials
Which compound, and why
PTFE (Virgin, Glass, Bronze, Graphite)
The standard backup-ring material — high compressive strength, wide temperature range, chemically inert; supplied virgin or glass/bronze filled for extra extrusion resistance.
NBR (Nitrile / Buna-N)
90-durometer nitrile backup rings, a lower-cost option for moderate-pressure hydraulic service where PTFE isn't required.
Applications
Where it's used
High-pressure hydraulic and pneumatic cylinders, wide extrusion-gap glands, and elevated-temperature service where the primary elastomer softens and becomes extrusion-prone.