PTFE O-Rings
Universal chemical resistance and the widest temperature range of any sealing material — from cryogenic to high-heat applications.
Overview
PTFE (Polytetrafluoroethylene) is a semi-crystalline fluoropolymer rather than a rubber elastomer, but its chemical inertness and temperature range make it an essential sealing material for applications where no elastomer will survive. With resistance to virtually all industrial chemicals — including concentrated acids, strong alkalis, solvents and oxidising agents — PTFE is the default specification when chemical compatibility is the primary concern.
PTFE O-rings operate from -200°C (liquid nitrogen service) to +260°C, the broadest temperature range of any sealing material. They are FDA compliant, physiologically inert and self-lubricating, eliminating the need for external lubrication in many applications.
The key engineering limitation of PTFE is its lack of elasticity — it does not compress and recover like rubber. PTFE O-rings rely on controlled groove dimensions and mechanical compression for sealing. They are used primarily in static sealing applications: flange seals, valve seals, fitting seals and face seals. For dynamic applications, PTFE lip seals or spring-energised PTFE seals are used instead of standard O-ring profiles.
Material Properties
| Temperature Range | -200°C to +260°C (-328°F to +500°F) |
| Hardness | 55–65 Shore D |
| Tensile Strength | 20–35 MPa |
| Elongation at Break | 200–400% |
| Coefficient of Friction | 0.05–0.10 (self-lubricating) |
| Specific Gravity | 2.13–2.19 |
| Color | White / Natural |
| FDA Compliance | Yes — 21 CFR 177.1550 |
| Chemical Resistance | Resistant to virtually all chemicals |
Typical Applications
Chemical Processing
Valve and pump seals handling concentrated acids, alkalis, chlorinated solvents and aggressive oxidising agents
Pharmaceutical
FDA-compliant static seals in drug manufacturing, pure steam systems and high-purity fluid handling
Cryogenics
Seals in liquid nitrogen, liquid oxygen and LNG systems operating at -196°C and below
Semiconductor
Ultra-high purity seals in semiconductor fab equipment handling aggressive process chemicals
Food & Beverage
Inert, non-stick seals in food processing where flavour transfer must be eliminated
Chemical Compatibility Summary
Compatible With
- - Virtually all chemicals
- - Strong oxidizing acids
- - Aromatic and chlorinated solvents
- - Cryogenic fluids
- - Steam and hot water
Incompatible With
- - Molten alkali metals
- - Fluorine gas at high temperatures
- - Chlorine trifluoride
- - Practically none in standard applications
Compare Nearby Materials
FEP Encapsulated
Use this when you need chemical resistance with more elastic recovery.
View FEP EncapsulatedSpring Energized Seals
Best path when PTFE performance is needed in dynamic or cryogenic sealing.
View Spring Energized SealsFurther Reading
PTFE vs FEP Encapsulated
Static chemistry, recovery limits, and where encapsulated designs fit better.
Read articleSpring Energized Seals vs O-Rings
When plain PTFE and standard elastomers stop being enough for motion or vacuum.
Read articleKey Advantages
Universal Chemical Resistance
PTFE is resistant to virtually all industrial chemicals including concentrated sulfuric acid, hydrofluoric acid, strong alkalis and most organic solvents. Only molten alkali metals and fluorine gas attack PTFE.
Extreme Temperature Range
From -200°C in cryogenic service to +260°C in continuous heat. No other standard sealing material covers this range in a single compound.
Self-Lubricating Surface
PTFE has the lowest coefficient of friction of any solid material (0.05–0.10). No external lubrication required, eliminating lubricant compatibility concerns and reducing contamination risk.
FDA and USP Compliant
Virgin PTFE is FDA compliant under 21 CFR 177.1550 and meets USP Class VI requirements for pharmaceutical and medical device applications. Fully extractable documentation available.
Frequently Asked Questions - PTFE
Can PTFE O-rings be used in dynamic sealing applications?
Standard PTFE O-rings are not recommended for dynamic applications due to cold flow (creep) under load. For dynamic service requiring PTFE's chemical resistance, spring-energised PTFE lip seals or filled PTFE compounds should be specified.
What is the difference between virgin PTFE and filled PTFE O-rings?
Virgin PTFE is pure polytetrafluoroethylene — maximum chemical resistance but prone to cold flow. Filled PTFE incorporates glass fibre, carbon, bronze or other fillers to improve mechanical properties and creep resistance while maintaining most of the chemical resistance.
Does PTFE absorb fluids?
No. PTFE has virtually zero fluid absorption. Unlike rubber elastomers that can swell in incompatible fluids, PTFE maintains its dimensions in essentially all chemical environments.
How are PTFE O-rings installed differently from rubber O-rings?
PTFE O-rings require tighter groove tolerances than rubber O-rings because they do not stretch elastically. They are typically installed with a mandrel or installation tool to avoid deformation. Groove dimensions must follow PTFE-specific design guidelines — contact us for groove design data.
Are PTFE O-rings suitable for high-pressure applications?
PTFE has limited extrusion resistance compared to hard rubber compounds. For high-pressure static seals, anti-extrusion back-up rings or filled PTFE compounds are recommended. Consult us for pressure-specific design guidance.