Polyimide (Kapton) Capillary Tubes for Temperature Sensors
Thin-wall polyimide capillary for thermocouple and RTD protection. Polyimide capillary protects sensor elements while staying thin and flexible across a wide temperature span. We draw it to the sensor OD with tight wall. Used as a sheath or liner for thermocouples and RTDs where space and response time matter. Polyimide stays flexible and stable over a wider high-temperature span; PTFE leads on ch
Thin-wall polyimide capillary for thermocouple and RTD protection. Polyimide capillary protects sensor elements while staying thin and flexible across a wide temperature span. We draw it to the sensor OD with tight wall. Used as a sheath or liner for thermocouples and RTDs where space and response time matter. Polyimide stays flexible and stable over a wider high-temperature span; PTFE leads on ch
Technical specifications
| Material | Polyimide (Kapton) |
| Temperature | -269 to +400 degC |
| Wall | Thin, tight tolerance |
| Use | Thermocouple / RTD sheath |
Information required for quotation
| Base tube | Approved material grade, ID, OD, wall and conditioning as per drawing |
| Datums | Drawing datum scheme and measurement reference |
| Key dimensions | Feature positions, depths, pitch and diameters reviewed before quotation |
| Thread / profile | Standard or custom profile, class, depth, engagement and gage method |
| Other features | Holes, slots, steps, chamfers, cuts and marking |
| Acceptance | Tolerances, sampling, gages, FAI and inspection report |
| Order | Prototype and production quantity, packaging and delivery target |
Applications by industry
- RTD and thermocouple sensor capillary sleeving
- High-temperature probe wire insulation
- Aerospace and lab instrument sensor leads
- Thin-wall insulating tubing over fine sensor wires
- Heat-shrinkless precision slewing for signal pairs
- Sensor fatigue and moisture barrier sleeving
Why polyimide (Kapton) for this application
Polyimide handles wide temperature swings with a thin wall and low creep, keeping small sensor-millivolt signals cleanly isolated even near hot probes.
Hygroscopic unless conditioned/coated; confirm moisture and dielectric vs service. Thin wall + heat can still degrade — derate for continuous high temp.
Standards: IEC 60672, ASTM D5487, IPC (film basis).
Feature and remaining-wall review
ID/OD sintered to size; CNC turning for ends, slots and holes. PTFE requires sharp tools to avoid chatter. Review feature depth, edge distance and remaining wall against critical geometries. Capability is confirmed on your drawing, not from a blanket tolerance.
Inspection and traceability
We state the control plan with you. Batch traceability links raw material lot to finished part.
- First-article inspection (FAI) per your plan
- In-process dimensional checks at every station
- Batch certificate of conformance (COA) supplied on request
- Lot traceability to incoming material certificate
- Dielectric strength and insulation resistance testing available on request
Related components
PTFE Tubing for Medical Devices
Related insulation component from the WELLELE catalog.
Mylar Shrink Tubing
Related insulation component from the WELLELE catalog.
Silicone-Coated Fiberglass Sleeving
Related insulation component from the WELLELE catalog.
Common questions
Is PTFE chemically inert?
Yes. PTFE resists all common acids, bases, solvents and fuels except molten alkali metals and fluorine at elevated temperature. No post-processing needed for chemical resistance.
What tolerances can you hold on PTFE tubing?
ID/OD ±0.05 mm on standard sizes; tighter tolerances available with grinding. PTFE is sized by sintering, so critical dimensions are best held by finish grinding after forming.
Can PTFE be threaded or machined?
PTFE can be CNC-turned for ends, slots and holes using sharp, low-speed tools to avoid chatter. Threads are best formed by machining rather than rolling.
Do you supply material certification for PTFE?
Yes. Each batch includes a material COA. First-article inspection and dielectric strength testing are available per your specification.
Polyimide vs PTFE for sensors?
Yes. Each batch includes a material COA. First-article inspection and dielectric strength testing are available per your specification.
Engineering Guides & Selection Notes
Related technical articles that help specify this product.
Get pricing for Polyimide (Kapton) Capillary Tubes for Temperature Sensors
Attach the drawing with annual volume. We check the material against your duty and tolerance, verify ID / OD / wall / features, and respond with manufacturability notes and pricing.