PTFE Seal Material Selection Reference
PTFE is the default answer when elastomers cannot handle temperature, chemicals or dry running, but the filler decides how the seal wears, how the shaft survives and whether the compound meets food or pharma rules. This reference compares the common grades side by side.
| PTFE grade | Typical filler | Wear and load | Friction | Chemical resistance | Mating surface notes | Typical use | Watch out for |
|---|---|---|---|---|---|---|---|
Virgin PTFE | None | Soft, creeps under load, lowest wear resistance | Lowest | Excellent with nearly all fluids | Gentle on soft shafts and aluminum | Food, pharma, chemical, static and low-load seals | Cold flow under load; poor in high-pressure dynamic use |
Glass filled PTFE (15 to 25 percent) | Glass fiber | Good wear resistance, reduced creep | Low to moderate | Very good; attacked by strong alkalis and hydrofluoric acid | Can abrade soft shafts, needs hard and smooth surface | General hydraulic and pneumatic seals, backup rings | Soft mating metal; HF and caustic service |
Glass and MoS2 filled PTFE | Glass fiber plus molybdenum disulphide | Good wear, improved running-in | Lower than glass alone | Very good; limited with strong alkalis | Hard shaft preferred | Rod and piston seals in hydraulic cylinders | Aggressive alkaline media |
Carbon filled PTFE (about 25 percent) | Amorphous carbon | Good wear and compressive strength | Low | Excellent, including many acids and alkalis | Gentler on shafts than glass | Steam, hot water, chemical process seals | Not usually food grade; check conductivity needs |
Carbon and graphite filled PTFE | Carbon plus graphite | Good wear, self-lubricating | Very low | Excellent | Handles minor dry running and softer shafts | Rotary seals, compressors, dry running | Colour and shedding may not suit clean applications |
Bronze filled PTFE (40 to 60 percent) | Bronze powder | High load and wear capability, high thermal conductivity | Moderate | Limited in acids and oxidising media | Needs hard, smooth shaft | High-load hydraulic bearings and wear rings | Corrosive fluids; food and pharma use |
Polyimide filled PTFE (about 15 percent) | Polyimide | Excellent wear, low abrasion of mating part | Low | Very good | Suited to softer shafts, stainless and aluminum | Dry running, cryogenic and aerospace seals | Higher cost; check steam compatibility |
PEEK filled PTFE | PEEK powder | High strength and wear resistance | Low | Very good | Moderate hardness on mating part | High pressure, aggressive media, rotary | Cost; verify with supplier for temperature extremes |
Stainless steel filled PTFE | Stainless steel powder | Good compressive strength, low creep | Moderate | Good; depends on steel grade | Hard shaft required | High temperature steam, chemical process | Abrasion of soft shafts |
FDA-compliant virgin PTFE | None | Soft, similar to virgin | Lowest | Excellent | Soft or polished surfaces | Food, beverage and pharmaceutical contact seals | Use only grades certified for the regulation you must meet |
General trade information, not a substitute for supplier data. Property levels depend on filler percentage, resin and processing. Typical PTFE service range is about -200 to +260 deg C; verify limits for the filler and seal design. Always confirm FDA, USP or other regulatory status on the specific compound and lot certificate.
Carry material grade through your ERP
An optional discussion on keeping filler grade and certification attached to seal items and purchase orders.
Optional. The tool and every export work without this. No spam.
How to use it
Search by filler, fluid, or application word such as hydraulic, steam, dry running or food. Each row summarises wear, friction, chemical resistance, mating surface notes and common applications. Use it to shortlist two or three grades, then confirm the choice with the seal manufacturer for your pressure, speed, temperature and surface finish. Export the table to Excel to attach to a quote or a material approval request.
- Start with the media and mating surface; those eliminate most grades.
- For food and pharma, use only certified virgin or approved grades.
- Treat the table as a shortlist tool, not as a design approval.
Why fillers matter
Virgin PTFE has the best chemical resistance and the lowest friction but creeps and wears under load. Fillers raise compressive strength and wear life, and each has a trade-off. Glass improves wear but can abrade a soft shaft. Carbon is gentler on shafts and thermally conductive. Bronze carries high load but corrodes in acids. Polyimide wears gently on soft mating surfaces and suits dry running. The right grade balances wear life against shaft damage and chemical compatibility.
Selecting for the application
Pressure and speed set the load on the seal and therefore the filler need. Fluid sets the chemical limit, since glass and bronze give up some resistance. Shaft hardness and finish decide whether glass is safe. Operating temperature rarely limits PTFE itself, but the energising spring or backup ring may. In spring-energised designs the jacket material is chosen from this table while the spring is chosen separately for corrosion resistance.
Common mistakes
The usual errors are using glass-filled PTFE on a soft aluminum or stainless shaft, selecting bronze for a wet corrosive service, and assuming every white PTFE seal is food grade. Another is ignoring creep: PTFE does not recover like rubber, so a dimension that loses preload after the first thermal cycle needs a spring or elastomer energiser. Document the grade on the drawing and in the ERP item description to avoid substitution.
Frequently Asked Questions
Which filled PTFE is best for hydraulic rod seals?
Glass and MoS2 filled, bronze filled and carbon filled grades are all common for hydraulic seals. The right one depends on rod hardness, pressure and fluid. Glass-filled needs a hard, smooth rod; carbon and polyimide are gentler on softer rods.
Is glass-filled PTFE FDA compliant?
Not by default. FDA-compliant grades are normally virgin PTFE or specific certified compounds. Glass-filled grades are generally not food contact grades. Always confirm the regulatory status on the compound datasheet and certificate for the lot you buy.
What temperature can PTFE seals handle?
PTFE is usually rated from about -200 deg C to +260 deg C, with the filler and seal design affecting practical limits. Pressure and creep reduce the usable range at the upper end. Confirm limits with the seal supplier for your application.
Why use a spring-energised PTFE seal?
PTFE has little elastic recovery, so a metal spring or elastomer energiser supplies the sealing force and compensates for wear and thermal changes. This lets PTFE seal at low pressure and cryogenic temperature where an O-ring would harden or fail.
If PTFE grade substitutions are a recurring quality escape, we can show how the grade is carried through your ERP item master and checked automatically against approved drawings.
Related Tools
O-Ring Thermal Expansion and Clearance Calculator
Predict hot diametral clearance and hot squeeze when the bore, piston and elastomer expand at different rates between assembly and operating temperature.
Costing & FinanceCustom Seal Quote Estimator Worksheet
Build a line-by-line quote for custom seals with material, machine time, setup amortisation, scrap and margin, and see unit price, extended price and blended margin.
Industry TemplatesCustom Seal RFQ and Specification Template
A request-for-quote form that captures the application data a seal supplier needs to quote custom O-rings, lip seals, PTFE seals and gaskets correctly the first time.
Quality & InspectionO-Ring Gland Design Review Checklist
A structured design review for O-ring glands covering material selection, geometry, squeeze and stretch, surface finish, extrusion, assembly and inspection.
More Engineering & PLM tools
See all- O-Ring Gland Squeeze and Fill Calculator
- AS568 O-Ring Dash Size Reference
- SAP Super BOM Design Worksheet
- SAP Engineering Change Number Checklist
- SAP Document Info Record Template
- SAP Change Master and Revision Level Log
- SAP Engineering Change Request (ECR) Template
- SAP BOM Usage and Item Category Reference
- SAP Engineering Change Obsolescence Exposure Calculator
Keep exploring
Free tools
- Custom Seal RFQ and Specification TemplateA request-for-quote form that captures the application data a seal supplier needs to quote custom O-rings, lip seals, PTFE seals and gaskets correctly the first time.
- Custom Seal Quote Estimator WorksheetBuild a line-by-line quote for custom seals with material, machine time, setup amortisation, scrap and margin, and see unit price, extended price and blended margin.
- O-Ring Thermal Expansion and Clearance CalculatorPredict hot diametral clearance and hot squeeze when the bore, piston and elastomer expand at different rates between assembly and operating temperature.
Guides
- PTFE Seal Costing: Billet Yield, Machining Time and Filled GradesHow to cost machined PTFE and polymer seals: billet or tube yield, filled grades, machining cycle time, spring-energized assemblies and scrap allowances.
- How to Quote Custom Molded Rubber Seals and O-RingsHow to quote custom molded rubber seals: tooling amortization, cavities, cure time, compound cost, deflash and post-cure, plus where quotes go wrong.
- Material Certs and Lot Traceability for Seals and GasketsMaterial certs and lot traceability for seals and gaskets: compound certs, CoCs, cure dates, recall drills and records auditors and primes expect.