PTFE, FEP and PFA Heat Shrink Tubing: Which Fluoropolymer, and Why
Three materials, three different answers. The decision comes down to service temperature, recovery temperature, and what the tube has to survive.
The short answer
- Service below 200 °C and your line only has a heat gun: FEP. It recovers at 180 to 200 °C with standard tooling.
- Service up to 260 °C, chemical exposure, or semiconductor / aerospace duty: PTFE or PFA. Both share the -200 to +260 °C band.
- You need a melt-bondable, welded, leak-free assembly: PFA. It is the only one of the three that fuses to itself.
- Nothing in this family goes above 260 °C continuously. If your part runs hotter, the answer is a different material class, not a higher ratio of the same one.
Fluoropolymer heat shrink gets specified when polyolefin runs out of headroom: continuous heat above 125 °C, solvents, fuels, acids, or a surface that must not wet out or outgas. On paper the three materials look alike. All are chemically inert, all carry UL 94 V-0, and all are rated for insulation duty. The numbers that actually decide a build are the service ceiling, the temperature your line needs to recover the tube, and how much diameter change each size gives you.
That last point catches people. FEP and PFA are typically supplied at low shrink ratios, often around 1.3:1, which means the recovered diameter is only about 30 percent smaller than the supplied diameter. Polyolefin at 3:1 or 4:1 forgives a wrong size. Fluoropolymer at 1.3:1 does not. If you are used to sizing polyolefin, the same arithmetic will leave you with a tube that will not close onto the part.
Material comparison: the numbers that decide it
| Property | PTFE (Teflon) | FEP | PFA |
|---|---|---|---|
| Continuous service temperature | -200 to +260 °C | -200 to +200 °C | -200 to +260 °C |
| Short-term peak | ~300 °C | ~220 °C | ~300 °C |
| Recovery (shrink) temperature | 300 to 400 °C | 180 to 200 °C | 300 to 375 °C |
| Typical shrink ratio | 2:1 and 4:1 | ~1.3:1 | 2:1 |
| Dielectric strength | ≥ 25 kV/mm | ≥ 25 kV/mm | ≥ 25 kV/mm |
| Chemical resistance | Near universal | Excellent (below PTFE) | Near universal |
| Transparency | Opaque, white or translucent | High clarity | Translucent |
| Melt-bondable / weldable | No | No | Yes |
| Flame class | UL 94 V-0 | UL 94 V-0 | UL 94 V-0 |
| Relative material cost | Highest | Lowest of the three | Mid to high |
Ratios, walls and sizes are confirmed against your part drawing at quotation. Where a catalogue lists only 1.3:1 for FEP, a 2:1 PTFE or PFA tube may be the better route for a stepped part.
Pick this, skip this
Specify fluoropolymer heat shrink when
- Continuous service is above 125 °C, or peaks land above 150 °C
- The tube sees fuels, solvents, hydraulic fluid, acids or steam
- The part sits in semiconductor, medical, aerospace or cryogenic equipment
- Outgassing and extractables matter, for vacuum or cleanroom duty
- Non-stick behaviour is required so the sleeve does not bond to the substrate
- The assembly must survive sterilisation cycles without cracking
Stay with polyolefin or another family when
- Service is 125 °C or below. Crosslinked polyolefin is far cheaper and recovers with a heat gun
- You need a wide diameter step on one joint. Use a 3:1 or 4:1 dual-wall polyolefin tube instead
- You need an adhesive-lined, immersion-rated seal. Adhesive-lined fluoropolymer is rare and expensive; a two-layer build usually wins
- The joint needs to stay flexible under continuous flex. PTFE is stiff; FEP and PFA bend better but still do not match a flexible elastomer sleeve
- Continuous service is above 260 °C. Move to a ceramic, melamine or glass-silicone system
Why the recovery temperature is a line problem, not a data-sheet problem
PTFE needs 300 to 400 °C to recover. That is above the damage threshold of most wire insulation, connector housings, solder masks and adjacent components. If your assembly has any of those within a few millimetres, the heat that recovers the PTFE can destroy them before the tube is even tight.
FEP recovers at 180 to 200 °C, which is reachable with a standard polyolefin-rated heat gun. That single fact is why FEP exists as a separate product rather than being folded into the PTFE line. On lab and industrial jobs at 200 °C or below, it is the practical choice: no oven, no specialised tooling, no thermal damage risk.
PFA recovers at 300 to 375 °C, in the same bracket as PTFE, but it can be melt-bonded and thermoformed. If you are building closed-end caps, welded joints or over-moulded assemblies, PFA is the material that lets you do it. That capability, not the temperature, is usually why a buyer pays PFA prices.
What goes wrong in the field
Sizing a fluoropolymer tube like a polyolefin one
At 1.3:1 the recovered diameter is only 30 percent smaller than supplied. Buyers used to 3:1 polyolefin order the size they would have ordered before, then find the tube will not close onto the part. Send the substrate OD and we size it, or move to a 2:1 or 4:1 PTFE grade.
Recovering PTFE with the wrong heat source
A polyolefin heat gun will not bring PTFE to 300 °C. The tube looks warm but never recovers, and the operator keeps adding heat until something adjacent fails. Match the tool to the material before the run starts, not after the first failed joint.
Assuming adhesive-lined fluoropolymer is off the shelf
Most fluoropolymer heat shrink is single wall. If you need a moisture seal plus chemical resistance, the reliable build is a polyolefin dual-wall tube for the seal with a fluoropolymer outer sleeve for the chemistry. We quote it as a two-part assembly.
Transparent tube behind UV
FEP clarity is the reason it gets picked, and also the reason it fails outdoors. Long-term UV exposure degrades the tube surface. For outdoor runs, either shade the sleeve or specify PTFE, which does not rely on transparency for the duty.
Specifying above the family ceiling
No fluoropolymer heat shrink is rated for continuous service above 260 °C. When a spec says 300 °C continuous, the correct answer is a different material class, not a more expensive fluoropolymer.
Forgetting the connector edge
A burr or a sharp terminal edge will pierce a thin fluoropolymer wall during recovery. Deburr, or add a protective inner layer. This shows up as a dielectric pass at 10 parts then a failure at a few thousand.
Related Engineering Guides
Components for this solution
PTFE / FEP / PFA Teflon Heat-Shrink Tubing
All three fluoropolymer heat shrink materials from one line, sized to substrate OD and service temperature.
Teflon Heat-Shrink Tubing
Shrink PTFE for chemically aggressive and high-temperature service where polyolefin is out of range.
PFA Heat-Shrink Tubing 2:1
Melt-bondable PFA tube for welded, closed-end and over-moulded assemblies at up to 260 °C.
PTFE Tubes
Pure and filled PTFE tube for fluid handling, electrical insulation and semiconductor duty.
PTFE Tubing for Medical Devices
Medical-grade PTFE liners and shafts with tight ID control and cleanroom-compatible handling.
Teflon Tube for Automotive High-Temp Cable
PTFE sleeving for engine-bay and powertrain wiring where the jacket sees sustained heat.
Silicone-Coated Fiberglass Sleeving
Flexible braided alternative when the duty needs flex rather than a rigid recovered wall.
Silicone-Coated Fire Sleeve
High-temperature fire protection for hydraulic lines and harnesses at 260 °C class.
Related solutions
Common questions
Which fluoropolymer heat shrink handles the highest temperature?
PTFE and PFA, both rated -200 to +260 °C continuous, with PTFE peaking near 300 °C short-term. FEP tops out at 200 °C service. Recovery temperature is a separate number: PTFE and PFA need 300 °C or higher equipment, while FEP recovers at 180 to 200 °C.
Can I install PTFE heat shrink with a standard heat gun?
Not reliably. PTFE recovers at 300 to 400 °C, beyond a polyolefin-rated heat gun. You need an oven or a hot-air tool rated for that range. If your line only has a heat gun, specify FEP.
Why would I pick FEP over PTFE?
When service stays at or below 200 °C, FEP recovers at 180 to 200 °C with standard tools and is simpler to install. You give up the higher ceiling and gain an easier line. FEP is also transparent, which matters when an inspector has to see the joint.
Is PFA just a high-temperature FEP?
No. PFA matches the PTFE service class at 260 °C and adds melt-bondability, so it welds into leak-free assemblies and thermoforms into closed-end caps. FEP is a lower-temperature material with an easy recovery, which is a different product decision.
What shrink ratios are available in fluoropolymer?
PTFE is commonly 2:1 and 4:1. PFA is available at 2:1. FEP is typically around 1.3:1. If your part has a large diameter step, a 4:1 PTFE tube is usually the only fluoropolymer option that will cover it, so plan the sizing early.
Can fluoropolymer heat shrink be adhesive-lined?
Rarely, and it is expensive. Most fluoropolymer heat shrink is single wall. When a spec needs both a moisture seal and chemical resistance, we quote a two-part build: a polyolefin dual-wall adhesive tube for the seal and a fluoropolymer outer sleeve for the chemistry.
What about continuous duty above 260 °C?
None of the fluoropolymer heat shrink materials qualify. Above 260 °C continuous, the answer moves outside this family to a ceramic, melamine, glass-silicone or mica system. Tell us the duty and we will point at the right class rather than sell you a higher ratio of the wrong one.
Will the tube survive cryogenic service?
Yes. PTFE, FEP and PFA stay usable down to around -200 °C and FEP remains flexible at cryogenic temperatures. This is one of the few duties where the fluoropolymers have no polyolefin competitor at all.
How do I size a fluoropolymer shrink tube?
Send the substrate OD, the largest feature the tube must pass over, and the smallest diameter it must grip after recovery. For PTFE and PFA we then pick the ratio and wall against the voltage and temperature duty. For FEP, expect to work within a narrow recovered range.
Does fluoropolymer heat shrink need to be cut before or after recovery?
Cut to length before recovery. Fluoropolymer does not re-melt once recovered, so a length mistake cannot be corrected by reheating. Add the longitudinal shrink allowance to your cut length, and allow more on high-ratio PTFE.
Do you supply material certificates and test data?
Yes. Each batch carries a material COA traced to the incoming resin certificate. First-article inspection, dielectric strength and dimensional reports are supplied against your inspection plan on request.
Can you print or mark the sleeve?
Yes. Identification bands, logos, temperature class and part numbers can be printed. On transparent FEP the print is legible through the wall, which some buyers use instead of a separate label.
What do you need to quote a fluoropolymer shrink job?
Material preference if you have one, substrate OD range, recovered diameter target, continuous and peak service temperature, chemical exposure, voltage class, the recovery equipment on your line, and annual volume. Send those and we will confirm the grade and size rather than quote a catalogue number.