PTFE vs FEP vs PFA Heat Shrink Temperature
Three fluoropolymers, three recovery temperatures, three shrink ratios. The choice between them starts with the heat source you actually have, because PTFE will not recover on standard shop equipment.
Grades side by side
| Grade | Shrink ratio | Recovery | Continuous range | Clarity | Where it fits |
|---|---|---|---|---|---|
| PTFE | 1.1:1 | Needs a source above 327°C | -65°C to +260°C | Opaque, translucent in thin sections | The highest temperature and chemical duty |
| FEP | 1.3:1 | Lower transition than PFA | -65°C to +260°C | Clear | Where moderate shrink and easier processing are enough |
| PFA | 4:1 | Above FEP, below PTFE | -65°C to +260°C | Clear | Large diameter changes and high purity work |
All three sit in the same continuous range, -65°C to +260°C, and all three are supplied transparent or natural to UL94 V0 and MIL-I-23053. The differences that decide the order are the shrink ratio and the equipment the recovery needs.
The ratio decides the sizing work
A 1.1:1 grade barely changes diameter, so it has to be ordered close to the part it covers. A 4:1 grade can pass a large section and close on a small one, which is what makes it usable over connectors and irregular assemblies. The sizing logic is the same one used for any sleeve, set out in shrink ratio.
The temperature decides the equipment
PTFE cannot be melt-extruded. The tube is paste extruded and sintered, then expanded below its crystalline melt point near 327°C, and recovery means heating above that point so the crystal structure re-forms. A standard heat gun and a bench hot air station do not reach it reliably. FEP and PFA are melt-processable thermoplastics, extruded, mechanically expanded and heat set, and they recover at lower transitions.
How to choose
- Start with the part. Note the largest section the tube must pass and the smallest it must close on, then compare that with the shrink ratio.
- Check the hottest point against the -65°C to +260°C continuous range, which all three grades share.
- Check the chemistry. All three sit in the highest chemical resistance class, so the decision rests on temperature, ratio and clarity.
- Confirm your heat source before you commit to PTFE. This is the step that sends tubes back.
- State the documentation requirement if the parts are audited, so lot paperwork matches your file.
What to send
Send the component diameters, the length, the chemistry, the temperature at the hottest point and the equipment you will use. We return the grade and the size.
Frequently asked questions
Why can a normal heat gun not recover PTFE?
PTFE is expanded below its crystalline melt point near 327°C and has to be heated above it to recover. Hand tools do not reach that reliably, so the tube stays partially expanded.
Do all three grades share the same temperature range?
Yes. PTFE, FEP and PFA are all rated -65°C to +260°C in our range, so the choice between them rests on ratio, clarity and processing rather than on continuous temperature.
Which grade gives the largest shrink?
PFA at 4:1. PTFE is 1.1:1 and FEP is 1.3:1, so both need to be ordered close to the part diameter.
Are the tubes transparent?
PTFE is opaque and only translucent in thin sections. FEP and PFA are clear, which is why they are used where the joint has to be inspected.
What documentation comes with the tubes?
The range is supplied to UL94 V0 and MIL-I-23053. State your filing requirement with the enquiry so the lot paperwork matches your audit.