Material Selection And Application Of Fluoropolymer-lined Pipe Fittings

A PTFE lined pipe combines a steel shell with a fluoropolymer inner layer that isolates the metal from corrosive media. PTFE handles -29°C to 180°C. PFA extends to 200°C with lower permeation. FEP covers steam and hot water up to 150°C. Modified PTFE offers enhanced flex life for cyclic services. Selection depends on temperature, chemical concentration, vacuum requirements, and service conditions.

How to select the right lining material

1. PTFE: Standard for acids, caustic, and solvents up to 180°C.

2. PFA: Same chemical resistance, lower permeation. For high-purity and services above 180°C up to 200°C.

3. FEP: Cost-effective for steam and hot water up to 150°C.

4. Modified PTFE: Enhanced flex life and lower permeation for cyclic services.

Common Design Pitfalls

• ⚡ PTFE above 180°C → Specify PFA.

• ❌ Loose liners in vacuum → Specify molded liners with dovetail retention.

• 🔍 Thin liners → Specify minimum 3-5 mm thickness.

• 📊 PTFE for aromatics → Verify chemical compatibility.

PTFE Lining Methods

Molded liners suit vacuum and service above 150°C. Isostatic molded offers highest density up to 200°C under vacuum. Loose-lined is cost-effective for general pressure but collapses under vacuum.

Liner Thickness and Permeation

PTFE liners range from 2-10 mm. Minimum 3 mm is standard. Thicker liners reduce permeation.

Permeation considerations:

• PTFE permeable to small molecules at elevated temperatures

• PFA offers lower permeation than PTFE

• Modified PTFE provides enhanced resistance

Expansion Joints – Flexible Connections

Teflon lined expansion joints provide flexible connections for corrosive piping systems. The PTFE liner covers all wetted surfaces, protecting metal bellows from chemical attack.

Applications: Chemical processing (acid lines), pharmaceutical (high-purity), water treatment (chemical dosing), food processing (non-stick surfaces).

Tee Fittings – Equal and Instrument Configurations

PTFE lined tee fittings are available in equal and reducing configurations. The seamless PTFE liner covers all internal surfaces, providing corrosion protection at branch connections. PTFE lined equal tee fittings maintain full-bore flow through all three branches. PTFE lined instrument tee fittings incorporate a side branch for pressure gauges, sensors, or thermowells.

Instrument tee features:

• Side branch for instrumentation integration

• Full PTFE lining on all branches

• Carbon steel or stainless steel body

Applications

Chemical Processing: Strong acids, chlor-alkali, solvents. PTFE/PFA lining, molded construction.

Pharmaceutical: High-purity media. PFA lining, stainless steel shell.

Semiconductor: Ultrapure water, wet chemicals. 

Water Treatment: Chemical dosing, chlorine injection. PTFE lining, loose-lined for cost-effectiveness.

Lining Selection Guide

PTFE lined pipe with molded construction suits standard acids up to 180°C. PFA extends to 200°C for hot acids and high-purity applications. FEP offers a cost-effective option for steam and hot water up to 150°C. For vacuum service, specify molded or isostatic molded liners with mechanical retention. Teflon lined expansion joints provide flexible connections for corrosive piping systems. PTFE lined equal tee fittings maintain full-bore flow at branch connections. PTFE lined instrument tee configurations enable sensor integration without compromising corrosion protection. For services above 180°C, PFA is preferred over PTFE. Verify pressure-temperature rating against system operating conditions. PTFE lined pipe manufacturers offer molded, isostatic molded, and loose-lined constructions.

FVF PTFE Lined Equal Tee

• Its working temperature is high at the range of -29°C-180°C; except the molten alkali metals, element fluorine and aromatic hydrocarbon, lined products can be used in any chemical medium.
• Vacuum resistance. In the range of -29°C-150°C, it is applicable for vacuum condition. In chemical production, the vacuum condition occurs due to cooling, longitudinal emissions, or medium backflow. 
• It is high-pressure resistant . Within temperature working condition, it can sustain the working pressure of 3.0MPa.
• It is penetration Resistant.It has excellent antiosmosis by adapting the high-quality PTFE and making it of high density and enough thickness after advanced lining processing.
• PTFE advanced lining molding process achieved the status of syn chronous hot expansion or cold shrinkage for steel components and fluorine plastic. 

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