PTFE extruded tubes are fundamental components in numerous industrial applications, prized for their exceptional chemical resistance, high-temperature performance, and excellent electrical insulation properties. As a cornerstone of modern fluid handling and insulation systems, understanding their specifications and capabilities is crucial for engineers, procurement specialists, and designers. This guide provides a detailed breakdown of PTFE extruded tube parameters, features, and answers to common technical questions.
The following table outlines the standard technical specifications for our range of PTFE extruded tubes. Custom sizes and tolerances are available upon request.
| Parameter | Standard Value / Range | Test Method / Notes |
|---|---|---|
| Standard Inner Diameter (ID) | 1 mm to 50 mm (0.04" to 2.0") | Custom diameters outside this range available. |
| Standard Wall Thickness | 0.5 mm to 5 mm (0.02" to 0.2") | Wall thickness is proportional to tube diameter. |
| Standard Length | Up to 5 meters (16.4 feet) continuous | Can be cut to specific lengths as required. |
| Color | Natural White (Opaque) | Can be pigmented for color-coding; black is common. |
| Specific Gravity | 2.15 - 2.20 g/cm³ | ASTM D792 |
| Tensile Strength | 20 - 35 MPa (2900 - 5000 psi) | ASTM D638 |
| Elongation at Break | 200 - 400% | ASTM D638 |
| Dielectric Strength | > 40 kV/mm (in air, on 1mm wall) | ASTM D149 |
| Volume Resistivity | > 10¹⁸ Ω·cm | ASTM D257 |
| Coefficient of Friction | 0.04 - 0.1 (Dynamic, against steel) | ASTM D1894 |
| Continuous Service Temperature | -200°C to +260°C (-328°F to +500°F) | Short-term peaks up to 300°C are possible. |
PTFE extruded tube offers unparalleled chemical resistance. The table below indicates its performance against common substances.
| Chemical Family | Examples | Resistance Rating | Notes |
|---|---|---|---|
| Strong Acids | Hydrochloric Acid, Sulfuric Acid, Nitric Acid | Excellent | Resistant to all concentrations, even at high temperatures. |
| Strong Bases | Sodium Hydroxide, Potassium Hydroxide | Excellent | No known reaction, even with concentrated solutions. |
| Organic Solvents | Acetone, Toluene, Chloroform, Ethanol | Excellent | Will not swell or degrade. |
| Oxidizing Agents | Hydrogen Peroxide, Chlorine, Bromine | Excellent | Superior performance where other plastics fail. |
| Oils & Greases | Hydraulic Fluid, Motor Oil, Silicone Grease | Excellent | Non-absorbent and non-reactive. |
| Gases | Oxygen, Nitrogen, Chlorine Gas | Excellent | Very low permeability. |
What is the primary difference between extruded and skived PTFE tube?
Extruded PTFE tube is manufactured by forcing a PTFE paste through a die, creating a continuous, seamless length. This process results in a tube with high longitudinal strength and is cost-effective for long, continuous runs. Skived PTFE tube is made by shaving a thin film from a solid, molded PTFE block, which is then wound and sintered. Skived tubes can achieve tighter tolerances and thinner walls but are typically produced in shorter lengths and have a spiral seam.
Can PTFE extruded tubes be bent or shaped after manufacture?
PTFE extruded tubes have a degree of flexibility, especially in smaller diameters with thin walls. However, they are not designed for sharp, permanent bends. For complex routing, pre-formed bends or fittings are recommended. Attempting to force a sharp bend can lead to kinking or a reduction in the internal diameter, which compromises flow and pressure rating.
What are the pressure ratings for PTFE extruded tubes?
The pressure rating of a PTFE extruded tube is not a fixed value; it is highly dependent on the inner diameter, wall thickness, temperature, and the presence of any fittings. As a general rule, pressure capability decreases as temperature increases. For specific pressure calculations, it is essential to consult engineering data or our technical team, as the relatively low tensile strength of PTFE compared to metals means it is not typically used for high-pressure hydraulic applications without reinforcement.
Is PTFE extruded tube suitable for food and pharmaceutical applications?
Yes, specific grades of virgin PTFE are compliant with FDA (Food and Drug Administration) regulations CFR 21 177.1550 and other international food contact standards. It is critical to specify that you require a food-grade or USP Class VI certified PTFE when ordering for these sensitive applications to ensure the material meets the necessary purity and extraction requirements.
How does temperature affect the dimensions and performance of PTFE extruded tube?
PTFE has a relatively high coefficient of thermal expansion. The tube will expand when heated and contract when cooled. This dimensional change must be accounted for in system design, especially in long, fixed runs, to avoid stress build-up. While PTFE does not melt, it does have a glass transition temperature, and its mechanical properties, such as stiffness and tensile strength, will change across its service temperature range.
What is the best method for cutting PTFE extruded tube?
For a clean, square cut that will not obstruct fluid flow or impede fitting attachment, use a sharp blade or a fine-tooth saw. A rotary tube cutter also works well. Avoid crushing the tube in a vise while cutting. After cutting, it is advisable to deburr the inner and outer edges lightly to remove any loose fragments and ensure a smooth surface.
Can PTFE extruded tubes be joined or welded?
PTFE cannot be welded using traditional thermal methods like other thermoplastics because it does not melt. The most common and reliable methods for joining PTFE tubes are using mechanical fittings (e.g., compression fittings, flare fittings) or, for a permanent bond, thermal butt welding under specific pressure and temperature conditions in a specialized machine. Adhesive bonding is generally not effective due to PTFE's non-stick properties.
What are the limitations of using PTFE extruded tube?
While PTFE is an outstanding material, it has limitations. Its mechanical strength and stiffness are lower than many metals and some other engineering plastics, making it unsuitable for high-pressure or high-load structural applications without support. It is susceptible to permeation by certain gases. It also has poor resistance to creep (cold flow) under sustained mechanical load, meaning it can deform over time. Furthermore, it can be abraded by filled compounds or sharp particles.
How should PTFE extruded tubes be stored?
PTFE extruded tubes should be stored in a cool, dry, and dark environment away from direct sunlight and heat sources. They should be stored straight, not coiled tightly, to prevent permanent deformation or kinking. Avoid storing them in a way that subjects them to continuous compression or stress. Keeping them in their original packaging until use is recommended to prevent contamination.
Are there any safety considerations when machining or handling PTFE tubes?
PTFE is chemically inert and stable under normal conditions. However, when heated above 300°C (572°F), it can begin to decompose and release toxic fumes. Therefore, any machining process that generates significant heat, such as high-speed sawing or drilling, should be conducted with adequate ventilation or local exhaust to prevent fume inhalation. Always refer to the material's Safety Data Sheet (SDS) for detailed handling instructions.