Kaxite Sealing manufactures PTFE O-rings by precision machining virgin, modified (TFM), glass-filled, carbon-graphite, bronze or stainless-steel filled PTFE stock. Unlike elastomer O-rings they do not swell, harden or degrade in aggressive chemistry — they seal by mechanical interference and resistance to extrusion, keeping their shape across pH 0–14 and -200 to +260 °C. Available to AS568, ISO 3601 metric and fully custom dimensions. Procurement teams choose us for factory-direct bulk pricing, documented traceability and 7–15 day lead times.
Elastomer O-rings seal by elastic recovery — squeeze them and they spring back. PTFE does not spring back; it stays where you put it. That is what makes it work where elastomers fail: it does not swell, does not harden, does not crack under UV, and does not leach plasticisers. But it also means gland design has to change — tighter radial squeeze, closer tolerances, and often a back-up ring behind it in high-pressure service. Kaxite's engineering team reviews every gland before quoting.
Inert across pH 0–14, resisting concentrated sulfuric and nitric acid, aqua regia, strong bases, solvents and oxidising agents. No swelling, no extraction, no contamination.
Service range -200 to +260 °C continuous, with short-term peaks higher. Retains flexibility at LNG temperatures without becoming brittle; resists steam and process heat without softening.
Coefficient of friction 0.05–0.10 — the lowest of any solid material. Prevents stick-slip, reduces breakaway torque, and extends life in rotary and reciprocating service.
Water absorption below 0.01%. No dimensional change in humid or immersed service, and dielectric strength above 40 kV/mm for electrical isolation duty.
Precision machined from virgin PTFE, modified (TFM) PTFE or filled PTFE stock. Supplied to AS568 (inch) and ISO 3601 (metric) standard sizes, or fully custom dimensions to your gland drawing. Unlike elastomer seals, PTFE O-rings do not swell, harden or degrade in aggressive chemistry. Used for static face and radial sealing, and as back-up rings behind elastomer O-rings for anti-extrusion service at high pressure.
Maximum chemical purity, best dielectric properties. FDA 21 CFR 177.1550 compliant.
TFM grade with lower creep and weldability. Improved dimensional stability under load.
15–25% glass fibre. Improved creep resistance and compressive strength for static duty.
Superior wear resistance, higher thermal conductivity, electrically conductive. For dynamic service.
40–60% bronze. Highest thermal conductivity and load-bearing capacity for heavy-duty seals.
| Property | Test Method | Typical Value | Notes |
|---|---|---|---|
| Density | ASTM D792 | 2.15 – 2.20 g/cm³ | Virgin grade; higher for filled grades |
| Tensile Strength | ASTM D638 | 25 – 35 MPa | Reduced for bronze-filled grade |
| Elongation at Break | ASTM D638 | 200 – 350 % | Higher ductility than elastomer O-rings |
| Compression Set (22 h @ 25 °C) | ASTM D395 | 40 – 60 % | Higher than elastomer — gland design must compensate |
| Continuous Service Temperature | — | -200 to +260 °C | Cryogenic LNG through process steam |
| Thermal Conductivity | ASTM C177 | 0.25 W/m·K | Raised by carbon and bronze fillers |
| Coefficient of Friction (dynamic) | ASTM D1894 | 0.05 – 0.10 | Self-lubricating, no external lubricant required |
| Water Absorption | ASTM D570 | < 0.01 % | Dimensionally stable in humid service |
| Dielectric Strength | ASTM D149 | > 40 kV/mm | For electrical isolation duty |
| Standard Sizes | AS568 / ISO 3601 | ID 3 – 600 mm | Full custom dimensions available |
Yes, for many dynamic applications — particularly when filled with carbon or bronze. They are commonly used on rotary shafts, reciprocating rods and hydraulic/pneumatic cylinders. The key is proper gland design that accounts for PTFE's low elasticity and higher compression set compared to rubber. Our engineers can provide specific design guidance for dynamic use.
PTFE has a higher compression set (typically 40–60%) than high-performance elastomers like FKM (10–20%). PTFE O-rings rely more on inherent sealing force and resistance to extrusion than on elastic recovery. Gland design must accommodate this, often using tighter radial squeeze or backup rings in high-pressure applications to prevent gap extrusion.
Yes — PTFE is an exceptional material for high and ultra-high vacuum (UHV) applications. Its extremely low outgassing rate, minimal vapour pressure and resistance to permeation make it ideal. For critical UHV systems we recommend the virgin, unfilled grade, processed and handled to minimise surface contamination and particulate generation.
They are not truly elastic, so they are not ideal where significant stretch is needed to install over a spigot. Radiation resistance is lower than some elastomers. Pure PTFE can creep under heavy continuous load, which is why filled grades are used for those duties. They are not recommended for molten alkali metals or certain fluorine compounds at high temperatures.
Because they are machined rather than moulded, PTFE O-rings can be more delicate than rubber rings. Avoid sharp tools. For internal glands a tapered installation cone is recommended. Ensure gland and seal are clean and debris-free. PTFE does not typically require lubrication for installation, but a light film of compatible grease or system fluid can aid positioning. Handle with clean gloves for purity-critical applications.
Yes. Virgin PTFE is naturally white, but we can incorporate FDA-compliant pigments to produce O-rings in various colours for easy system identification, quality control or brand coding. This is common in complex fluid systems with multiple media, and in automotive and aerospace assemblies.
We maintain inventory of popular AS568 and metric sizes in key grades. For standard items, shipment is often within 24–48 hours. For fully custom machined sizes, large production runs or specialised filler compounds, typical lead times range from 2 to 6 weeks depending on complexity and quantity. Firm timelines are confirmed at quotation.
Sometimes — but not as a drop-in swap. Because PTFE does not recover elastically, an existing elastomer gland may need to be re-dimensioned for PTFE. In many cases, a PTFE back-up ring behind the existing elastomer O-ring is a better solution — it keeps the elastomer sealing behaviour while adding anti-extrusion protection. Share your gland drawing and our engineering team will advise which approach fits best.
Send us your inner diameter, cross-section, quantity, grade preference or finished-part drawing. Our export team replies within 24 hours and confirms grade selection, lead time, packaging and documentation before you place a bulk order.
