Ptfe-lined Worm Gear Plug Valve Design Standards And Application Guidelines

A lined plug valve uses a tapered plug with a fluoropolymer sleeve for corrosion resistance and tight shutoff. The plug rotates 90° to align the port with the pipeline for full flow or block it for shutoff. Lined plug valves meet API 6D, ASME B16.34, and ISO 17292 standards. Selection requires matching lining material (PTFE, PFA, or FEP) to service temperature and chemical compatibility.

How to select a lined plug valve based on design standards

1. Verify API 6D and ASME B16.34 compliance for pressure-temperature ratings.

2. Specify lining: PTFE for standard acids up to 180°C, PFA for hot acids and chlorine up to 200°C.

3. Confirm fire-safe design per API 607 or ISO 10497 for flammable services.

4. Ensure fugitive emissions compliance per ISO 15848-1 for stem sealing.

Common Design Pitfalls

• ❗ Non-fire-safe valves in flammable service → Specify API 607 fire-safe design.

• ⚠️ Ignoring fugitive emissions → Specify ISO 15848-1 for stem sealing.

• 🔧 Vacuum service: Liners collapse under vacuum → Specify locked-in liner with dovetail grooves.

• 📐 PTFE above 180°C: PTFE softens and deforms → Specify PFA above 180°C.

Lining Material Selection

A ptfe sleeved plug valve provides broad chemical resistance up to 180°C. A teflon lined plug valve (PTFE) suits standard acids, caustic, and solvents. PFA lined plug valves extend service to 200°C for chlorine, hot acids, and strong oxidizers. FEP lined plug valves suit steam and hot water up to 150°C.

Fire-Safe Design – API 607 Compliance

API 607 requires the valve to pass a fire test. Lined plug valves with PTFE sleeves are inherently fire-safe—PTFE provides primary seal, metal-to-metal contact provides secondary seal if PTFE burns away.

Fire-safe features:

• PTFE sleeve provides primary seal

• Metal-to-metal plug-to-body contact provides secondary seal

• Live-loaded stem packing maintains seal integrity

• Anti-static design prevents spark generation

Fugitive Emissions – ISO 15848-1

ISO 15848-1 provides testing procedures for stem seals. Lined plug valves with live-loaded stem packing achieve Class A or Class B leakage rates.

Packing features:

• PTFE V-ring packing: Standard

• Live-loaded spring system: Maintains compression

• Multiple packing rings: Secondary sealing

• Leak-off connection: Monitors packing performance

Liner Retention – Preventing Collapse

Dovetail grooves machined into the body lock the liner in place. T-slots provide additional retention for aggressive service. Locked-in liner designs are specified for vacuum service and thermal cycling.

Liner retention features:

• Dovetail grooves: Lock liner to body

• T-slots: Additional retention for aggressive service

• Mechanical locking: Prevents liner collapse under vacuum

• Spark-tested integrity: Verifies pinhole-free lining

Applications

Chlor-Alkali: Wet/dry chlorine, caustic soda, brine. PFA lining, locked-in liner, fire-safe, ISO 15848-1.

Chemical Processing: Strong acids, solvents, chlorinated hydrocarbons. PTFE/PFA lining, API 6D, fire-safe.

Petrochemical: Hydrocarbons, sour water, amine systems. PTFE lining, API 607 fire-safe.

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

Standard Compliance Summary

Lined plug valves meet API 6D, ASME B16.34, and ISO 17292 for pressure-temperature ratings and dimensional interchangeability. PTFE sleeved plug valves suit standard acids up to 180°C. Teflon lined plug valves with locked-in liners suit vacuum service. PFA lining extends service to 200°C for chlorine and hot acids. Fire-safe designs per API 607 provide secondary sealing. ISO 15848-1 compliant stem sealing controls fugitive emissions. Dovetail grooves prevent liner collapse under vacuum.

FVF Worm Gear Operated FEP PFA 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.

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Materials of Main Parts

Technical Specification