PTFE / Teflon Applications: Seals, Liners & More

PTFE's combination of near-universal chemical resistance, a continuous-use temperature of 500°F (260°C), and a coefficient of friction of 0.05–0.10 qualifies it for a wider range of demanding applications than almost any other engineering plastic. The applications below span chemical processing, semiconductor manufacturing, food production, electrical engineering, and precision mechanical systems — each making use of a different facet of PTFE's unusual property profile.

At a Glance

• Seals and gaskets: industry-standard choice for corrosive chemical service
• Bushings and bearings: self-lubricating, no grease required in many applications
• Chemical-resistant liners: pipe, vessel, and valve linings for aggressive reagents
• High-temperature insulation: wire, coaxial cable, and circuit board substrates
• Non-stick and release surfaces: industrial conveyor belting, roll covers, mold-release sheets
• Pharmaceutical and semiconductor: ultra-pure, non-contaminating, easy to clean
• Food processing: FDA 21 CFR 177.1550 compliance for direct contact

Seals and Gaskets

Static Sealing: Flanges and Valve Seats

PTFE cut-gaskets and sheet-lined gaskets are ubiquitous in chemical plant piping. The material maintains a gas-tight seal across the full range of industrial process fluids — including concentrated acids, alkalis, and solvents that would swell or degrade rubber, PTFE-free elastomers, or fiber-reinforced gasket composites. Typical forms are:

• Skived film cut gaskets (0.015–0.060 in. thick) for flat-face and raised-face ASTM B16.21 flanges
• Full-face sheet gaskets cut to flange bolt-hole patterns in thicknesses from 1/16 to 1/4 in.
• Envelope gaskets with a rubber or soft metal core jacketed in PTFE for applications requiring compression resilience

Dynamic Seals: Piston Rings, Rod Seals, Valve Stem Packing

For reciprocating or rotary motion, filled PTFE grades outperform virgin material. Carbon-filled (15%) or glass-filled (25%) grades carry higher PV limits and resist extrusion past the seal lip. PTFE piston rings in hydraulic cylinders operating with water-glycol or phosphate-ester fluids — which attack NBR and viton in some formulations — are a standard specification.

Virgin PTFE valve stem packing remains common in corrosive process valves where contamination from carbon or glass filler particles would be problematic (e.g., ultrapure chemical service, semiconductor wet benches).

Bearings and Bushings

Self-Lubricating Linear Bearings

PTFE's transfer-film lubrication mechanism deposits a molecular-thin layer on the mating metal surface, creating near-frictionless sliding without any applied lubricant. This property makes PTFE bushings standard in food processing machinery (no lubricant contamination risk), medical devices, and clean-room equipment.

Grade selection for bearings follows a simple hierarchy:

Thrust Washers and Slide Plates

Bridge bearings, industrial slide plates, and expansion joints use PTFE sheet bonded to stainless steel backing plates. The coefficient of friction (0.05–0.10) keeps structural movement forces manageable. Bronze-filled PTFE is preferred for high-load structural bearing applications because of its higher compressive strength and lower creep rate.

Chemical-Resistant Liners

Pipe and Fitting Liners

PTFE-lined pipe combines the structural strength of carbon steel or FRP with a chemically inert PTFE inner surface. Liners are typically 0.060–0.125 in. thick skived sheet rolled and heat-set into the pipe bore. This construction is cost-effective for 1–12 inch pipe carrying hydrofluoric acid, chlorine, or other reagents where solid PTFE pipe would be cost-prohibitive.

Where piping must transition to valves, PTFE-lined ball valves and butterfly valves use a similar approach — a molded PTFE liner bonded to the valve body interior and seat surfaces. These assemblies can handle temperatures from cryogenic to 450°F and essentially all industrial process chemicals.

Vessel and Reactor Liners

Pharmaceutical, agrochemical, and specialty chemical reactors use PTFE sheet liners in glass-lined steel vessels when the process temperature or chemistry exceeds what glass can handle, or where glass damage risk is high. PTFE's smoothness also reduces batch-to-batch contamination.

Compared to PVDF-lined equipment, PTFE-lined vessels cost more per unit but handle a broader chemistry spectrum, particularly fuming acids and halogenated solvents that PVDF cannot tolerate.

High-Temperature Electrical Insulation

Wire and Cable Insulation

PTFE-insulated hook-up wire is specified for aerospace, military (MIL-W-16878), and industrial applications where the conductor will see temperatures above 200°F (93°C) — the upper limit for PVC. PTFE's combination of:

• Dielectric strength: 480 V/mil
• Dielectric constant: 2.1 at 1 MHz (lowest of common solid insulators)
• Continuous temperature: 500°F (260°C)
• Chemical resistance: impervious to cable sheathing oils and industrial fluids

…makes it the preferred insulation for thermocouple extension wire, coaxial cable inner dielectrics (low loss at microwave frequencies), and downhole oilfield instrumentation.

PCB Substrates and Microwave Laminates

PTFE-woven-glass laminate (e.g., Rogers RT/duroid series) is the substrate of choice for microwave and millimeter-wave printed circuits. The low, stable dielectric constant of 2.1–2.5 (depending on glass content) allows controlled-impedance transmission lines to be designed with predictable electrical behavior across temperature extremes.

Non-Stick and Release Surface Applications

Industrial Conveyor Belting and Roll Covers

High-temperature conveyor belts in baking, confectionery, and adhesive film production use PTFE-coated fiberglass fabric. The non-stick surface releases product cleanly at temperatures up to 500°F, and the fabric provides structural strength PTFE alone cannot. Roll covers in corrugating, laminating, and printing presses use solid PTFE sleeves or PTFE-coated rubber for the same release properties.

Mold-Release Sheets

PTFE skived film (0.001–0.005 in.) placed between molded composite or rubber parts and tooling surfaces prevents adhesion without release agents. Aerospace composite fabrication heavily uses PTFE release film in autoclave and press operations.

Pharmaceutical and Semiconductor Manufacturing

Ultra-Pure Process Equipment

Semiconductor wet-bench equipment (HF etching, wet cleans, rinse tanks) is built almost entirely from PTFE and PVDF. PTFE is the preferred material where temperature exceeds PVDF's limit or where the chemicals involved (fuming nitric, piranha solution) attack PVDF. Wetted surfaces that contact ultra-pure deionized water and process chemicals are machined from virgin PTFE billet to minimize particle generation and ionic contamination.

Laboratory Ware and Pharmaceutical Processing

PTFE labware (beakers, crucibles, stir bars, tubing) is chemically inert, autoclavable, and transparent to microwave radiation. In pharmaceutical API manufacturing, PTFE-lined reactors and transfer tubing prevent metal leaching and simplify cleaning validation — the non-stick surface cleans thoroughly, reducing cross-contamination risk between batches.

Food Processing

Virgin PTFE's FDA 21 CFR 177.1550 listing makes it suitable for direct food contact. Typical applications include:

• Seals and O-rings in dairy, brewing, and beverage equipment
• Bushing stock in food-grade conveyors where lubricant-free operation is required
• Non-stick conveyor belting in bakery and confectionery lines
• Valve seats in CIP (clean-in-place) systems that cycle through hot caustic and acid sanitizers

Note that not all filled grades maintain FDA status — see PTFE FDA food-grade compliance for grade-specific guidance.

Comparison: When to Choose PTFE vs Alternatives

The UHMW vs PTFE comparison covers situations where UHMW is a cost-justified substitute and where PTFE is non-negotiable.

Related Guides

More related guides

Cross-cluster suggestions to help shoppers and engineers explore adjacent topics:

Applications

• Bushings Bearings
• Wear Strips Guide Rails
• Electrical Insulation

Industries

• Semiconductor
• Oil Gas

Compare to other materials

• Peek Vs. Ptfe
• Uhmw Vs. Ptfe Teflon
• Pvdf Vs. Ptfe

Frequently asked questions — Ptfe Teflon FAQ