Virgin PTFE
Low friction and near-universal chemical resistance for scarf-cut and spiral rings.
Backups
Moss Seal supplies back-up rings to protect O-rings from extrusion where pressure, temperature, or gland clearance exceeds what the elastomer can handle alone. Fitted on the low-pressure side of the O-ring, the ring bridges the extrusion gap and lets the O-ring carry higher pressures without nibbling, extrusion damage, or premature failure. We match ring style, material, and dimensions to your gland design and operating conditions, whether you are upgrading an existing seal or specifying a new assembly.
ENGINEERING
Cross-section design & operation
A hard, low-friction ring fills the clearance gap behind the O-ring so the elastomer seals against a supported surface rather than an open gap.
Ring styles
Solid rings offer the highest extrusion resistance but require a split gland or open groove. Scarf-cut and spiral rings install into closed grooves, with the cut sized to close under pressure so no unsupported gap remains.
How it works
As system pressure loads the O-ring, it deforms toward the low-pressure side. The back-up ring sits in that path and takes the extrusion load, leaving the O-ring to do the sealing while the ring handles the gap.
Pressure response
With a single back-up ring, O-ring service pressure can be extended well beyond its unsupported limit, and larger diametral clearances become acceptable. For pressure in both directions, a ring is fitted on each side of the O-ring.
SELECTION
Materials & advantages
Performance advantages
Prevents O-ring extrusion · Higher pressure capability · Tolerates larger clearances · Resists nibbling · Broad chemical resistance · Longer O-ring life
