Back-Up Rings
Performance Sealing Inc. (PSI) manufactures precision back-up rings designed to prevent O-ring extrusion in demanding high-pressure and high-temperature sealing applications. When system pressure exceeds the O-ring's resistance to being forced into the extrusion gap between mating components, a back-up ring acts as a rigid barrier — holding the O-ring in place so it can continue sealing without being damaged.
PSI back-up rings are precision manufactured from high-performance polymer materials — including PTFE, PEEK, and proprietary Duron® polymers — and are available in seven configurations to match your gland geometry and installation requirements.
Back-Up Ring Benefits
- Excellent high-temperature capability and resistance to extrusion compared to conventional polymer sealing products
- Engineered for high-pressure applications where standard O-ring performance is insufficient
- Precision manufactured from Duron® polymers to enhance baseline seal performance
- Seven configurations available to accommodate split glands, full O-ring style glands, and bidirectional pressure applications
The Diametrical Gap — defined as the clearance between the rod or bore and the seal housing — is a critical factor in back-up ring selection. The standard recommended "E" diametrical gap should be observed during hardware design and validated prior to installation.
Back-Up Ring Configurations
PSI offers seven back-up ring configurations. Selection is based on gland type, installation constraints, operating pressure, and extrusion gap dimensions. For a complete proposal, submit a request for quote and we will respond immediately.
 |
Solid Back-Up Ring | Solid back-up rings are the ideal anti-extrusion device, offering maximum performance. Best used in split glands where installation is not a constraint. | RFQ |
|---|---|---|---|
 |
Standard Duty Single Turn Ring | Designed for full O-ring style glands where solid back-ups cannot be installed. Wound into place during installation. | RFQ |
 |
Double Thick Solid Back-Up Ring | Used when extra high-pressure capability is required in split glands. Greater cross-section provides increased resistance to extrusion. | RFQ |
 |
Double Thick Single Turn Ring | For full-height glands requiring extra high-pressure performance where solid back-ups cannot be installed due to gland geometry. | RFQ |
 |
O-Ring Contour Back-Up Ring | Contoured to conform closely to the O-ring geometry, allowing a double-thick back-up ring in glands that cannot support a standard single-thick ring. | RFQ |
|
Single Cammed Back-Up Ring | Selected when operating pressures exceed standard back-up ring limits or when extrusion gaps are extra wide. Mechanically deforms to close off the extrusion gap. | RFQ |
 |
Double Cammed Back-Up Ring | Used when tolerances are extra wide or when both the ID and OD of the seal gland have extrusion gaps. | RFQ |
These recommendations are guidelines only. Each sealing system must always be thoroughly tested by the customer or a qualified test lab to determine the actual high-pressure performance of the sealing system. High-pressure applications require testing that must include the maximum operating temperature at pressure and duration the seal will be exposed to in the actual application.
Back-Up Ring FAQs
What is a back-up ring and what does it do?
A back-up ring is a rigid, washer-like ring manufactured from hard materials such as PTFE or PEEK. Its sole purpose is to prevent O-ring extrusion — the process where system pressure forces the soft O-ring material into the gap between mating components. The back-up ring installs in the same groove as the O-ring, on the low-pressure side, physically blocking the extrusion gap and allowing the O-ring to maintain its seal integrity under pressure.
When do I need a back-up ring?
Back-up rings are recommended in four situations:
- High-pressure applications — generally above 1,500 PSI (100 bar)
- Applications with large extrusion gaps due to manufacturing tolerances
- High-temperature environments where heat softens the O-ring, reducing its resistance to extrusion
- Dynamic (reciprocating) applications where constant movement increases the risk of O-ring nibbling
In applications with bidirectional pressure, a back-up ring should be installed on each side of the O-ring.
What materials are PSI back-up rings made from?
PSI manufactures back-up rings from PTFE (Teflon), PEEK (polyetheretherketone), and proprietary Duron® polymer materials. Material selection depends on operating pressure, temperature range, and chemical exposure. PSI engineering staff can recommend the optimal material for your specific application.
What back-up ring configurations does PSI offer?
PSI offers seven configurations: Solid Back-Up Ring, Standard Duty Single Turn Ring, Double Thick Solid Back-Up Ring, Double Thick Single Turn Ring, O-Ring Contour Back-Up Ring, Single Cammed Back-Up Ring, and Double Cammed Back-Up Ring. Configuration is selected based on gland geometry, installation constraints, and operating pressure.
How do I choose between a solid and a single-turn back-up ring?
A solid back-up ring provides maximum anti-extrusion performance and is preferred where gland geometry allows for straight installation. A single-turn ring is used when assembly constraints prevent a solid ring from being installed — it can be wound into place in a full O-ring style gland. Double-thick versions of both are available for extreme-pressure applications.
Contact our technical sales staff today to discuss your application's operating, hardware, and commercial conditions to develop the best-performing seal solution.
Request A Quote Online Or Call Us At 866.429.2536