Features And Material Selection Of Fluorine-lined Plug Valves

A lined plug valve controls corrosive fluids across chemical, petrochemical, pharmaceutical, and metal processing plants. The fluoropolymer liner isolates the metal body from aggressive media. PTFE handles -29°C to 180°C. PFA serves -29°C to 200°C. FEP covers -29°C to 150°C. The tapered plug design provides a self-wiping action that clears debris from sealing surfaces.

How to select a lined plug valve for your corrosive service?

1. Identify the media composition, concentration, and suspended solids.

2. Determine the maximum operating temperature and pressure.

3. Match the lining: PTFE for standard acids ≤120°C, PFA for hot acids >120°C or oxidizers, FEP for steam and hot water.

The Tapered Plug Design

The plug valve uses a tapered plug with a through port. Rotating the plug 90° aligns the port for full flow or blocks it for shut-off. The tapered design allows in-line seat adjustment without removing the valve.

Key features:

• Self-wiping action clears debris during rotation

• Full-port design offers minimal flow resistance

• In-line adjustability extends service life

• Three-way configurations enable flow diversion

A ptfe plug valve handles suspended particles without seal damage. Lined plug valves conform to API 6D and ASME B16.10 dimensions.

Lining Material Selection

PTFE (Standard Duty)

A ptfe lined plug valve operates from -29°C to 180°C. Pressure ratings reach PN 16 or Class 150. Services: hydrochloric acid, sulfuric acid (≤98%), nitric acid, caustic soda.

PFA (High-Temperature / Oxidizer Duty)

Continuous service reaches +200°C. A pfa lined plug valve handles hot concentrated acids, oleum, bromine, and high-purity chemicals. The liner is anchored using T-slots or dovetail grooves.

FEP (Steam & Hot Water)

FEP suits saturated steam and hot water up to 150°C. Cost-effective for utility services.

Liner Retention

The liner must stay attached to the metal body under all conditions. Valve bodies incorporate dovetail grooves or T-slots for mechanical locking.

Retention requirements:

• Dovetail grooves or T-slots anchor the liner

• Cast-in recesses ensure strong adhesion

• Locked-in design handles vacuum service

A ptfe lined plug valve manufacturer specifies mechanical locking for vacuum-rated valves.

Sealing System

The tapered plug and body bore create the primary seal. Cast-in ribs concentrate compression for a full circumferential seal.

Sealing features:

• Primary seal: tapered plug-to-bore interference

• Secondary seal: PFA reverse lip diaphragm prevents stem leakage

• Adjustable seal: cover bolts maintain sealing

A pfa lined plug valve uses this dual system for bubble-tight shut-off.

Industry Applications

Chemical Processing – Sulfuric, hydrochloric, nitric, hydrofluoric acid, aqua regia. Self-wiping action suits suspended particles.

Petrochemical and Refining – Hot acids, oleum, hydrocarbons. Locked-in lining withstands thermal cycling.

Pharmaceutical and High-Purity – PFA for low extractables. Smooth surface prevents contamination.

Metal Processing – Strong acids and oxidizers. In-line adjustability reduces downtime.

Actuation Options

Actuator types:

• Manual lever: lockable

• Worm gear: self-locking for larger sizes

• Pneumatic: remote on-off

• Electric: modulating control

ISO 5211 mounting pads allow easy actuator mounting. V-port plugs are available for throttling.

Selection Checklist

1. Define media, concentration, and temperature.

2. Select lining:

   • Standard acid/caustic ≤120°C → PTFE.

   • Sulfuric acid >98% or hot acid >120°C → PFA.

   • Saturated steam ≤150°C → FEP.

3. Verify pressure class (PN 10/16, Class 150/300).

4. Confirm liner retention features.

5. Specify port configuration (2-way or 3-way).

6. Select actuation type.

7. Verify face-to-face dimensions (ASME B16.10).

Chemical Resistance Quick Reference

Sulfuric acid

• ≤98%, ≤120°C → PTFE

• ≤98%, 120–200°C → PFA

• Oleum → PFA only

Chloride and caustic

• HCl, any %, ≤100°C → PTFE

• Wet chlorine → PFA

• NaOH ≤50%, ≤120°C → PTFE

Utilities and solvents

• Saturated steam → FEP (≤150°C)

• High-purity water → PFA

• Organic solvents → PTFE (≤180°C)

Standard acids and caustics ≤120°C: A ptfe lined plug valve with locked-in PTFE liner provides reliable service.

Hot acids, oxidizers, or high-purity: A pfa lined plug valve is required. Lower permeation justifies the premium.

Steam service: FEP offers a cost-effective option where temperature is ≤150°C.

After material selection, verify liner retention matches pressure and vacuum rating. Confirm the sealing system provides primary and secondary barriers. Check actuation torque against operating torque at maximum temperature. For three-way applications, confirm port arrangement matches flow diversion. Verify P-T rating against surge pressure and actuator sizing against differential pressure.

FVF Pneumatic PTFE Lined Plug Valve

• 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.

• FVF lined plug valve can be equipped with a manual handle or with a pneumatic or electric actuator. A full range of accessory items are available including limit switches, solenoid valves, positioners and manual override devices.

Product Parameter

Materials of Main Parts

Technical Specification