What is PTFE?
PTFE (polytetrafluoroethylene) is a plastic from the fluoropolymer family, best known under the brand name Teflon. It has exceptionally low friction, is almost chemically inert, repels water and stays stable at high temperatures. Its melting point is around 327 °C.
Properties that make it useful
- Very low coefficient of friction: parts slide easily over one another
- Chemically resistant to almost all acids, alkalis and solvents
- Water- and dirt-repellent
- UV and weather resistant
- Hard to bond: without special surface treatment, almost nothing sticks to PTFE
Uses in construction
| Use | What it does |
|---|---|
| Sliding bearings | In bridges and large structures, a PTFE layer slides on stainless steel so that beams can expand and contract without damaging the bearings |
| Membrane roofs | Glass-fibre fabric coated with PTFE forms light, translucent canopies for stadiums, entrances and stations |
| Thread sealing | PTFE tape seals threaded joints in water and gas pipework |
| Seals and slide strips | Gaskets, slide strips in sliding systems, coatings |
Don’t confuse it with ETFE: a related fluoropolymer used as clear film in inflated cushions. PTFE membranes are usually white and translucent rather than clear.
Tips for PTFE tape
- Clean and degrease the thread.
- Wrap in the direction of the thread so the tape does not ride off as you screw the joint together. Looking at the end of the male thread, that is clockwise for a standard right-hand thread.
- Leave the first thread bare so no tape gets pushed into the pipe.
- Keep the tape taut and use no more layers than needed; too much tape can split a fitting.
- For gas, only use tape approved for gas (standard EN 751-3). Work on gas pipes should be done by a registered engineer.
Health and environment
- Do not overheat. Heated far above normal service temperatures, PTFE gives off harmful fumes. Do not cut or grind it hot and never burn it.
- PFAS. As a fluoropolymer, PTFE falls within the broad PFAS group. The EU is assessing a proposal to restrict PFAS, with separate conditions for fluoropolymers, so rules on use and disposal may change.
Related terms
- Plastics
- Sliding bearing
- Glass-fibre fabric
- Membrane in construction
- Polyester
Want to learn more about construction terms? Visit our knowledge base at fredsdiyplans.com.