Introduction
In hydraulic and pneumatic systems operating under high pressure, O-rings can be vulnerable to a critical issue: extrusion. When an O-ring is forced out of its groove into the mechanical gap between two sealing surfaces, it can become damaged or deformed. This compromises sealing performance and often leads to premature failure.
A smart and effective solution to this issue is the anti-extrusion ring. Easy to implement, cost-effective, and highly adaptable, anti-extrusion rings extend the lifespan of your O-rings and improve the overall reliability of your systems, even in extreme conditions.
1. What is O-Ring Extrusion?
Extrusion occurs when pressure forces an O-ring out of its groove and into the mechanical clearance (gap) between two assembled parts. This typically results in:
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Surface tearing or nibbling
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Permanent deformation
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Loss of sealing capability
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Equipment breakdown
Extrusion is most likely when:
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The system is under high pressure
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The clearance gap is large
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The O-ring is too soft
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There’s no supporting backup ring present
2. The Role of the Anti-Extrusion Ring
The anti-extrusion ring, also known as a backup ring, is a supporting element inserted in the same groove as the O-ring. It serves as a physical barrier, preventing the O-ring from being forced into the clearance gap.
Anti-extrusion rings:
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Protect O-rings from damage
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Enable use under higher pressures
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Enhance seal performance
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Extend service life
When should you use an anti-extrusion ring?
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When system pressure exceeds 50 bar
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When dealing with pulsating pressures
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If the mechanical gap is wide
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For bidirectional sealing applications (use two rings—one on each side of the O-ring)
💡 Note: For pressures under 50 bar, using an O-ring made from a higher Shore A hardness elastomer (minimum 80 Shore A in pulsating applications) may be sufficient.
3. Types of Anti-Extrusion Rings
ULTIMA offers multiple ring configurations, each suited to different installation needs.
➤ Flat Anti-Extrusion Ring
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Economical and simple design
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Easy to manufacture and install
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Available in split or solid versions
➤ Concave Anti-Extrusion Ring
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Contoured shape that matches the O-ring profile
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Better fit and retention in the groove
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Reduces risk of displacement during assembly
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Available in split or solid versions
➤ Spiral Anti-Extrusion Ring
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Helical structure for flexible adjustment
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During installation, compress the spiral to reduce its diameter, insert it into the groove, then release it to fit snugly
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Ideal for non-standard diameters
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Can be cut and adjusted for perfect fit
4. Materials for Anti-Extrusion Rings
Choosing the right material depends on your application’s pressure, temperature, chemical compatibility, and mechanical stresses.
🔹 Plastomers (PU, HPU)
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High-performance polyurethane
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Excellent wear and extrusion resistance
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Available in various hardness grades
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Recommended for dynamic or high-load systems
🔹 Elastomers (NBR, EPDM, HNBR, FPM, AFLAS)
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Excellent chemical resistance
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Withstand high temperatures
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Ideal for aggressive fluids, steam, or oils
🔹 Thermoplastics (POM, PTFE, PEEK)
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Very high extrusion resistance
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Precision machining tolerances
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Suitable for critical sealing conditions and harsh chemical environments
5. Advantages of Using Anti-Extrusion Rings
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✅ Prevents O-ring extrusion and deformation
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✅ Protects sealing systems from premature failure
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✅ Easy to implement and cost-effective
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✅ Compatible with standard (AS), metric, and custom O-ring dimensions
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✅ Adaptable for static and dynamic sealing
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✅ Available in split, solid, or monobloc formats
6. Custom Manufacturing by ULTIMA
ULTIMA offers a comprehensive custom production service for anti-extrusion rings tailored to your exact specifications.
🛠 In-house capabilities:
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Internal production up to 500 mm diameter
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Prototyping to medium series (up to 500 parts)
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No tooling fees
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Fast turnaround times
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Monobloc ring options available for non-modifiable housings (eliminates incorrect mounting direction)
🧪 From prototype to series
Thanks to a unique production process, ULTIMA develops fully functional prototypes, which, once validated by the client, are reproduced in small or medium series using high-precision injection or machining technologies.
7. Typical Applications
Anti-extrusion rings are used across industries requiring high-pressure and reliable sealing:
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Hydraulics and pneumatics
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Petrochemical and chemical plants
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Energy and power generation
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Aerospace and marine systems
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Rail and heavy transport
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Industrial machinery and robotics
Conclusion
The anti-extrusion ring is a vital component in any sealing system exposed to high pressure or mechanical stress. By supporting the O-ring and preventing damage, it ensures long-term sealing reliability, minimizes downtime, and protects your equipment investment.
Whether you need standard or custom anti-extrusion solutions, ULTIMA’s engineering and production team is ready to deliver high-quality, precisely tailored products with speed and reliability. From single prototypes to mid-size production runs, we ensure total control and full traceability at every step.
Contact ULTIMA today for a free consultation or quote, and optimize your sealing performance with expert-engineered anti-extrusion rings.
🔍 Need a quote or technical advice? Contact our team today and benefit from our speed, precision, and industrial expertise!