When a process fluid is too aggressive for any metal — when it would corrode stainless steel, hastelloy, or glass-lined pipe within months — PTFE pipe is the engineer's answer. Ram extruded PTFE pipes and tubes are the standard choice for transferring concentrated acids, caustic solutions, solvents, and other aggressive chemicals in industrial piping systems.
This guide covers everything you need to specify and purchase the right PTFE pipe or tube: manufacturing method, size range, pressure ratings, applicable standards, and selection criteria for the most common industrial applications.
How PTFE Pipes are Manufactured
PTFE cannot be processed by conventional thermoplastic extrusion because it doesn't melt to a flowable state. Instead, PTFE pipe is made by the ram extrusion process — a semi-continuous technique in which PTFE powder is fed into a heated cylindrical die and advanced by a hydraulic ram in repeated strokes. The result is a continuous pipe or tube with consistent wall thickness and excellent mechanical properties along its length.
Ram extruded PTFE pipe has superior longitudinal strength and density uniformity compared to moulded PTFE alternatives, making it the preferred form for pressure-containing applications. Paste extruded PTFE tubing (used for smaller bore sizes and flexible applications) is a separate product made by a different process.
Standard Size Range
| Bore (ID) | Wall Thickness | OD Range | Standard Lengths |
|---|---|---|---|
| 6 mm | 2 mm | 10 mm | 300–600 mm |
| 10 mm | 2–3 mm | 14–16 mm | 300–1000 mm |
| 15 mm | 2.5–3 mm | 20–21 mm | Up to 1200 mm |
| 20 mm | 3 mm | 26 mm | Up to 1500 mm |
| 25 mm | 3–4 mm | 31–33 mm | Up to 1500 mm |
| 32 mm | 4 mm | 40 mm | Up to 1500 mm |
| 40 mm | 4–5 mm | 48–50 mm | Up to 1500 mm |
| 50 mm | 5 mm | 60 mm | Up to 1500 mm |
| 65 mm | 5–6 mm | 75–77 mm | Up to 1200 mm |
| 80 mm | 6 mm | 92 mm | Up to 1200 mm |
| 100 mm | 7–8 mm | 114–116 mm | Up to 1000 mm |
| 150 mm | 9–10 mm | 168–170 mm | Up to 800 mm |
| 200 mm | 10–12 mm | 220–224 mm | Up to 600 mm |
| 250–300 mm | Custom | Custom | Custom lengths |
Pressure Ratings
PTFE pipe pressure ratings depend on bore size, wall thickness, and operating temperature. Key design points to note:
- PTFE softens progressively above 150°C, reducing its pressure-containing capability. Derate the working pressure at elevated temperatures.
- For high-pressure corrosive service, PTFE pipe is typically installed as a liner inside a carbon steel or stainless steel outer pipe — the PTFE provides chemical resistance, the metal provides structural strength.
- At ambient temperature, small-bore PTFE pipes (up to 50 mm ID, 5 mm wall) will handle working pressures of 6–10 bar gauge in straight runs without external support.
- PTFE pipe should always be supported at intervals not exceeding 300–500 mm to prevent sagging under its own weight in elevated installations.
PTFE Pipe vs PTFE-Lined Pipe: Which to Use?
| Factor | Solid PTFE Pipe | PTFE-Lined CS/SS Pipe |
|---|---|---|
| Pressure rating | Moderate (up to ~10 bar at ambient) | High (as per outer pipe rating) |
| Pipe diameters | Up to ~300 mm bore practical | Any bore — lining applied to any diameter |
| Cost | Higher per unit length | Lower for large bore |
| Installation | Straightforward; uses standard PTFE fittings | Requires flanged ends; no field cutting |
| Flexibility | Rigid; minimum bend radius required | Rigid (outer pipe) |
| Chemical resistance | Identical | Identical (PTFE contact surface) |
| Inspection/maintenance | Easy to inspect bore condition | Liner inspection requires borescope |
| Best application | Small to medium bore; labs; pharma; direct PTFE fittings | Large bore; high pressure; industrial pipework |
Applications by Industry
Chemical Plant Acid Lines
Transfer of HCl, H₂SO₄, HNO₃, HF, and mixed acids where metal pipe would corrode within months. PTFE pipe gives years of maintenance-free service.
Pharmaceutical Process Lines
Virgin PTFE (FDA 21 CFR compliant) for transfer of solvents, reagents, and intermediates in API synthesis and formulation. Zero contamination risk.
Semiconductor / Electronics
Ultra-pure PTFE tubing for chemical delivery systems in chip fabrication — no metal ion contamination at ppb levels that would destroy sensitive devices.
Water Treatment
PTFE pipe for dosing lines handling chlorine, hypochlorite, sodium bisulphite, and coagulant acids in water and wastewater treatment plants.
Oil & Gas Sampling
PTFE instrument tubing for sampling lines and analyser connections where hydrocarbon streams and H₂S would degrade other materials.
Dip Tubes & Vessel Liners
PTFE pipes used as dip tubes in acid storage tanks, reactor vessels, and chemical drums — protecting the internal metallic structure from corrosive contents.
Machining and Fabrication
PTFE pipes can be machined on standard CNC lathes to create flanged ends, threaded connections, or custom profiles. They can be drilled, faced, and bored with standard high-speed steel tooling. Key tips for machining PTFE pipe:
- Use sharp tools — dull tools tend to deform PTFE rather than cut it cleanly.
- No coolant required; PTFE machines dry without heat buildup.
- Clamp gently — excessive chuck pressure can deform the bore.
- Allow dimensional stabilisation before final measurement — PTFE can recover slight deformation after machining.
Frequently Asked Questions
What is the maximum operating temperature for PTFE pipes?
PTFE pipes can operate continuously up to 260°C. However, pressure capability reduces significantly above 150°C. For high-temperature, high-pressure service, consult our engineering team for specific wall thickness and support requirements at your operating conditions.
Can PTFE pipe be bent or curved on site?
Ram extruded PTFE pipe is relatively rigid and should not be cold-bent on site — it will crack rather than bend. For applications requiring curved runs, use straight pipe sections with PTFE elbow fittings, or use paste extruded PTFE tubing (smaller bores) which has more flexibility.
How do you join PTFE pipes to flanged equipment?
The most common method is to machine a flange face directly into the PTFE pipe end (turned flange or stub-end with loose backing flange). PTFE stub-ends with stainless steel backing flanges are widely used for sanitary and chemical service. Threaded PTFE fittings are used for smaller bore sizes.
What grades of PTFE pipe are available?
We manufacture PTFE pipes in virgin PTFE, glass-filled PTFE (15–25%), and carbon-graphite filled PTFE. Virgin PTFE is by far the most common for pipe applications. Filled grades are occasionally used for pipe components where improved creep resistance or conductivity (anti-static) is required.
Order PTFE Pipes & Tubes from Hindustan Nylons
Standard sizes in stock. Custom bore, wall thickness, and length to order. Export shipments to Gulf, Europe, USA, and Southeast Asia.
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