When a process requires both chemical resistance and structural strength — when pure PTFE pipe would be too weak for the pressure involved, or when a steel vessel must be protected from a corrosive product — PTFE lining systems provide the answer. By combining the structural integrity of carbon steel or stainless steel with the chemical inertness of PTFE, lined pipe and vessel systems handle applications that no single material could manage alone.
Hindustan Nylons manufactures a range of PTFE liner products under the Trexonn brand, alongside standard PTFE pipe and tube liners, sheet liners, and custom lining components for pipes, vessels, fittings, and equipment.
What is a PTFE Liner?
A PTFE liner is a tube or sheet of PTFE that is placed inside a metallic outer structure — most commonly carbon steel (CS) or stainless steel (SS) pipe, valve body, or process vessel. The metal provides structural strength to contain pressure and resist external loads; the PTFE liner provides the chemical-resistant inner surface that is in contact with the corrosive process fluid. The result is a lined system that combines the best of both materials.
Types of PTFE Liner Products
PTFE Pipe Liners (Trexonn)
PTFE tubes precision-formed to fit inside standard carbon steel or stainless steel pipe bore. Available for pipe sizes ½" to 12" NPS and larger. Loose-fit or bonded installation. Flanged ends formed by cold-flanging the PTFE tube ends over the pipe flange face — creating a complete PTFE sealing surface at every joint.
PTFE Vessel & Tank Lining Sheets
Skived PTFE sheet (typically 2–6 mm thick) with chemically treated back face, bonded to the inner surface of steel tanks, columns, and vessels. Provides complete PTFE lining of internal surfaces exposed to corrosive media.
PTFE Fitting Liners
Moulded PTFE inserts for elbows, tees, reducers, and flanged fittings — maintaining continuous PTFE lining through changes of direction and size in lined piping systems.
PTFE Valve Body Liners
Precision-moulded PTFE bodies for lined valves — ball valves, diaphragm valves, and plug valves — where both the valve body and ball/disc are PTFE-lined for complete corrosion resistance in aggressive chemical service.
PTFE Flange Face Gaskets (Stub-End)
PTFE stub-end flanges that slip into the pipe bore and are retained by a loose backing flange — creating a PTFE sealing surface at each flanged joint without the need for separate gaskets. Standard in pharmaceutical and food-grade lined systems.
Custom Lined Equipment
PTFE-lined reactor nozzles, agitator housings, pump impellers, and custom process equipment — designed to customer drawing and supplied complete with PTFE lining installed.
PTFE Lined Pipe: The Engineering Solution for Corrosive Service
PTFE-lined carbon steel pipe (often called "Trexonn pipe" in India, or "PTFE-lined pipe" internationally) is the most economical and practical solution for large-bore corrosive liquid service. It combines:
- Pressure rating: Full pressure rating of the outer carbon steel pipe (typically 10–40 bar for standard CS pipe at service temperature)
- Chemical resistance: Complete PTFE surface in contact with process fluid — resists all acids, bases, and solvents that PTFE resists
- Economics: Significantly cheaper per metre than solid PTFE pipe for large bore (above 75mm ID) — solid PTFE pipe above 100mm bore is very expensive
- Standard pipe fittings: Uses standard CS pipe flanges, supports, and fittings — no special tooling or expertise required for installation beyond standard pipefitting trades
The Flanging Process: Critical to Liner System Integrity
The weakest point in any PTFE-lined pipe system is the flange joint. At each flanged connection, the PTFE liner tube must be cold-flanged over the pipe flange face to create a continuous PTFE surface from bore to sealing face. This cold-flanging process — done with a heated die that progressively forms the PTFE tube end into a flange — requires skill and the right tooling to produce a flat, uniform flange that seals properly when the bolted joint is assembled.
Hindustan Nylons supplies lined pipe with flanges already formed — the cold-flanging is done at our facility under controlled conditions, eliminating field flanging and the quality risks it involves. Each lined pipe spool is pressure-tested before dispatch.
Applications of PTFE Lined Systems
| Industry | Application | Chemical Service |
|---|---|---|
| Chlor-alkali plants | Chlorine gas and hydrochloric acid piping | Cl₂, HCl, NaOH |
| Acid plants (H₂SO₄, HNO₃) | Acid transfer and distribution lines | H₂SO₄ up to 98%, HNO₃, oleum |
| Pickling and plating plants | Acid treatment line piping | HCl, H₂SO₄, HF, mixed acids |
| Fertiliser plants | Phosphoric and sulphuric acid circuits | H₃PO₄, H₂SO₄, ammonia |
| Pharmaceutical plants | Solvent and reagent transfer | All organic solvents, acids, bases |
| Semiconductor fabrication | Process chemical distribution | HF, HCl, H₂SO₄, ultra-pure water |
| Water treatment | Chemical dosing lines (chlorine, acid, base) | Cl₂, NaOCl, H₂SO₄, NaOH |
Frequently Asked Questions
What is Trexonn and how does it differ from standard PTFE lined pipe?
Trexonn is Hindustan Nylons' brand name for our PTFE and fluoropolymer liner products — similar to how Turcite is a brand name for a PTFE composite bearing material. Trexonn lined pipes use the same PTFE liner technology as generic "PTFE-lined pipe" but are manufactured to our specific quality standards with fully documented batch traceability and pressure testing. The PTFE material itself is standard virgin PTFE conforming to ASTM D1457.
How long do PTFE pipe liners last?
In properly designed and installed PTFE-lined systems handling chemicals within PTFE's compatibility range, service lives of 15–25 years are achievable. The liner must be replaced when: permeation of aggressive gas through the liner causes blistering of the outer steel (detected by corrosion of the outer pipe), when the liner develops stress cracks from thermal cycling, or when the PTFE surface shows significant erosion from abrasive slurry service. Regular visual inspection of the inner bore at maintenance shutdowns is recommended.
Can PTFE lined pipe be bent or curved?
PTFE-lined carbon steel pipe should not be cold-bent — the liner will crack or wrinkle in the bend zone. For changes of direction, use pre-fabricated PTFE-lined elbows (short or long radius). Hindustan Nylons fabricates PTFE-lined elbows and fittings to your system layout drawings.
Trexonn Liners & PTFE Lined Pipe Systems
Hindustan Nylons manufactures Trexonn PTFE pipe liners, vessel lining sheets, and complete lined pipe spools for chemical industry applications. Tell us your pipe size, chemical service, and pressure class.
Request Liner System Quote →