Materials And Selection Of Fluorine-lined Plug Valves

A lined plug valve handles chlorine, caustic soda, and hot electrolytes through a fluoropolymer lining that isolates the metal body from chemical attack. The tapered plug design provides a self-wiping action that clears debris from sealing surfaces during each quarter-turn operation. PTFE handles standard acids up to 180°C. PFA serves chlorine and high-temperature services up to 200°C with lower permeation.

How to select a lined plug valve

1. Choose liner material: PFA for chlorine and high temperatures ≤200°C, PTFE for standard acids ≤180°C.

2. Verify liner retention: T-slots or dovetail grooves for vacuum service.

3. Specify stem sealing: PFA reverse lip diaphragm for toxic media.

4. Select actuation: manual lever for on-off, worm gear for larger sizes.

Common Application Pitfalls – Why and How to Avoid

• ⚠️ Unlined valves in chlorine service: Unlined carbon steel valves in wet chlorine corrode within 2-4 weeks. → Specify PFA-lined plug valves; service life extends to 5-10 years.

• 🔒 Ignoring vacuum conditions: Standard liners collapse under vacuum. → Specify T-slots or dovetail grooves locking liner to body.

• ✅ Overlooking stem sealing: Toxic chlorine requires secondary stem seal. → Specify PFA reverse lip diaphragm.

• ⛔ Using standard plugs without in-line adjustment: Wear creates leak paths. → Specify adjustable plug design with top-entry bolts.

Why Chlor-Alkali Plants Depend on Lined Plug Valves

Chlor-alkali production involves electrolysis of brine to produce chlorine gas, hydrogen, and caustic soda. These services are corrosive and often involve crystallizing media. A ptfe lined plug valve with tapered plug design offers self-wiping action to handle salt crystals without seal damage.

Typical chlor-alkali services:

• Wet chlorine gas (<100 ppm moisture): PFA lining required

• Dry chlorine gas (>100 ppm moisture): PTFE lining acceptable

• Caustic soda transfer: PTFE lining handles NaOH at moderate temperatures

• Brine recirculation: Self-wiping plug design prevents solids accumulation

Service life comparison:

• Unlined valves: 2-4 weeks in wet chlorine service

• PFA-lined plug valves: 5-10 years

Lined Plug Valve vs Lined Ball Valve

• Ball valve: Ball cavity traps particles, causing wear.

• Plug valve: Tapered plug with self-wiping action clears debris.

• Plug valve advantages: In-line adjustment without pipeline disconnection, handles crystallizing media, sealing independent of line pressure.

Lining Material Selection – PFA vs PTFE vs FEP

A pfa lined plug valve with locked-in liner handles chlorine and extreme chemical services. A ptfe lined plug valve serves standard acid and caustic applications. Lined plug valve manufacturers offer both PFA and PTFE options. A ptfe plug valve with adjustable plug design suits in-line maintenance.

Lined plug valves conform to API 6D, ISO 17292, HG/T 3704, and ASME B16.10.

Design Features for Chlorine Service

• Liner Retention: T-slots or dovetail grooves lock the liner in place, preventing blow-out or collapse under vacuum.

• Solid Encapsulated Plug: Fully encapsulated with PFA, with anchor holes ensuring strong adhesion under extreme cycling.

• Secondary Stem Seal: PFA reverse lip diaphragm prevents external leakage.

• In-Line Adjustment: Top-entry bolts allow plug re-seating without pipeline disconnection.

Actuator and Torque Considerations

• Manual lever: Standard for on-off, locking lever handle

• Worm gear: Self-locking, recommended for DN 80 and larger

• Pneumatic: Remote on-off and emergency shut-down

• Electric: Modulating service with position feedback

• ISO 5211 mounting pad enables standard actuator installation

• Oversize actuator 25-30% for high-temperature operation

Industry Applications

Chlor-Alkali: Wet/dry chlorine, caustic soda, brine. PFA lining, locked-in liner, PFA reverse lip diaphragm, adjustable plug. 5-10 years service life.

Chemical Processing: Acids, chlorinated hydrocarbons. PTFE/PFA lining, self-wiping plug design.

Petrochemical: Sour water, amine systems. PTFE lining, API 6D compliance.

Water Treatment: Chemical dosing, chlorine injection. PTFE lining, manual/actuated operation.

For chlorine service: pfa lined plug valve with locked-in liner, PFA reverse lip diaphragm, adjustable plug. 5-10 years service life.

For standard acids ≤180°C: ptfe lined plug valve with self-wiping action, adjustable plug design.

For vacuum service: T-slots or dovetail grooves locking liner to body.

Actuation: manual lever for on-off, worm gear for DN 80+. Oversize actuator 25-30% for high-temperature operation.

FVF PTFE Lined Plug Valve With Worm Gear

• FVF lined plug valve is a valve that uses a plug body with a through hole as the opening and closing part and the plug rotates with the valve stem to realize the opening and closing action.
• FVF plug valve can be opened and closed quickly with small fluid resistance. Since the movement between the sealing surfaces of the plug valve has the function of wiping and can completely prevent the contact with the flowing medium when it is fully opened, so it can also be used for the medium with suspended particles.
• The plug and lined valve body have an ideal conical design.The top seal forms the second external seal to prevent the medium from leaking out of the valve stem when the sealing surface fails.
• By removing the four bolts on the bonnet, all components in the valve can be taken out.Then the valve parts can be directly replaced without removing the valve from the pipeline.
• Plug valves are mainly used to cut off the flow of medium and can also be used for medium distribution (three-way plug valve).
• FVF lined plug valve is applicable to any corrosive medium except "molten alkali metal and elemental fluorine".It is widely used in chemical industry, petroleum, medicine, food, steel smelting, paper making, water and electricity, environmental assurance etc.

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Materials of Main Parts

Technical Specification