Hydraulic & Fluid Seals
Back-up Rings, Anti-extrusion Rings
For static or dynamic sealing applications
Back-up rings provide added extrusion resistance and prevent damage to O-rings and seals when subjected to high pressures, larger extrusion gaps, and/or high temperatures.
The use of back-up rings can significantly increase the pressure rating of almost any seal. More Info…
They are used in conjunction with O-rings or dynamic seals for both static and dynamic sealing applications. The back-up ring is placed on the side of the seal opposite to the pressure and must be made out of a stronger material than the seal (Fig.1). For seals that are exposed to pressure from both sides, two back-up rings are required, one on each side. Alternatively, we recommend the use of one of our ultra-high pressure rod or piston seals, which are seal designs with an integrated back-up ring.
Back-up or anti-extrusion rings are used when:
- The operating pressure or pressure spikes exceed the seal’s extrusion resistance
- The extrusion gap exceeds maximum recommendation
- High temperature lowers the seal’s extrusion resistance and presents high risk for seal extrusion
- Thermo-cycling creates changes in the extrusion gap
- High pressure causes tube dilation
Back-up Ring Design Considerations: …
Back-up Ring Design Considerations:
There are two basic types of back-up ring designs:
-Standard or modular back-up rings (Fig.1)
Are rectangular or square rings with the same nominal radial cross-section as the seal. They typically will reduce a larger extrusion gap and can improve a seal’s extrusion resistance.
-Positively-actuated back-up rings (Fig.2)
Can be integrated in the seal or can be a specially shaped back-up ring which is automatically forced (actuated) by the system pressure axially and radially into the extrusion gap, reducing or closing the gap, preventing the seal from extruding and extending the seals pressure rating. This design provides the best protection against seal extrusion and seal damage. We offer a variety of ultra-high pressure rod and piston seals that offer this design feature.
The absence of a back-up ring (Fig.3 and Fig.4) can lead to seal extrusion and seal failure under high pressure, larger extrusion gaps, and/or high temperatures.
Dynamic and/or static sealing applications
Pressure: depending upon material, temperature and extrusion gap. Please contact engineering for material, size and design selection.
Temperature: -65°F to 500°F (-55°C to 260°C) depending upon material
Materials: PTFE, PTFE, PEEK, POM, Nylon, high-performance polyurethanes, engineering plastics, FDA-compliant material grades and proprietary specialized Duralast™, Duraloy™, and Permachem™ compounds among others.
Availability: More Info…
Standard, modular back-up ring to resist gap extrusion and damage to seals and O-rings. Also used in the same material as the seal when seal height/cross section/diameter make seal fitment challenging as one piece.
Contoured Back-up Ring
Contoured back-up ring for O-rings reduces damage or drag out during assembly and reduces risk of O-ring extrusion under pressure.
Ultra-High Pressure Back-up Ring
Positively activated contoured back-up ring for octi-ring, O-rings and seals to prevent extrusion under high pressure.
Ultra-High Pressure Back-up Rings
Positively activated specially-shaped back-up rings designed to eliminate extrusion and to accommodate “breathing” of cylinder tubes under ultra-high pressures by bridging the radial clearance gap between the piston and the bore as the pressure increases.
Internal Sealing Trapezoidal Back-up Ring
Positively activated design to resist internal seal extrusion/damage in ultra-high pressure sealing applications.
External Sealing Trapezoidal Back-up Ring
Positively activated design to resist external seal extrusion and seal damage in ultra-high pressure sealing applications.
External Back-up Ring
Positively activated back-up ring backing up on triangular faces to prevent external seal extrusion.
Internal Back-up Ring
Positively activated back-up ring backing up on triangular faces to prevent internal seal extrusion.
Applications & Industries
AHPSeals’ Back-up rings are currently in successful service in the following industries:
- Steel Works
- Government, Military and Defense
- Abrasive Substance Pumps and Valves
- Can and Package Filling Machines
- Oil-Field Exploration and Production
- Paint and Solvent Manufacture and Application
- Adhesives Dispensing Valves and Cylinders
- Chemical Pumps
- Cryogenic Liquid Control Components
- Liquid Handling Swivel Joints
- Construction Equipment
- Drilling Equipment
- Chemical Pumps and Valves
- Heavy Mobile Equipment
- Rubber and Plastics
- Food Processing
- Space Exploration
- Tire Production
- Low Friction
- Vacuum Service
- Automotive Plants
- Pharmaceutical Production
- Domestic Goods Production
- Many other applications
*Maximum values depend on seal material, seal configuration, media, temperatures, pressures, surface speed, dynamic running surface finish and working environment. Data provided are guidelines for ideal operating conditions. Seals cannot be operated at their upper pressure and speed ratings at the same time. For maximum seal life expectancy, do not operate your seal beyond 75% of any of its operating limits. Please consult engineering or call 1-800-283-7140 for advice.
American High Performance Seals assumes no obligation or liability for any advice furnished or results obtained with respect to these products. All such advice is given and accepted at the buyer’s risk.
This information, based on our experience, is offered as part of our service to customers. It is intended for use by persons having technical skill, at their own discretion and risk. We do not guarantee favorable results, and we assume no liability in connection with its use.
Any purchases resulting from information provided by American High Performance Seals, Inc., including proposals, recommendations and quotes, are subject to “AHPSEALS TERMS AND CONDITIONS OF SALE.”