PTFE Lined Butterfly Valve: Which Body Style and Size Do You Need?

Quick Answer:

There are three PTFE lined butterfly valve types based on end connections or body styles. Choose a wafer style for compact mid-line service. A lug body is ideal for end-of-line duty. Meanwhile, choose a double-flanged body for large-bore pipelines. The valves’ internal functions remain the same. They differ based on installation, support, maintenance, and whether they can be used for dead-end service.

Youfumi offers its lined valves in wafer, lug and flange connections, so buyers can specify each standard on one product line. Founded in 1989, Youfumi holds CE, ISO 9001 and ISO 14001 certificates and acts as a CNPC and SINOPEC supplier.

What Differences Separate Wafer, Lug and Double-Flanged PTFE Lined Butterfly Valve Bodies?

The key differences among lined valve types are connection method, face-to-face length, weight and cost, end-of-line service, removal method, and structural rigidity. Real-world applications also differ based on the valve type.

This table summarizes the differences among the three:

How Do Lining Thickness, Seat and Disc Materials Compare?

PTFE lining resists most acids, alkalis and solvents, while FEP and PFA melt-process into seamless linings. PFA also permeates less than PTFE, which helps with chlorine and strong acids.

• Lining thickness: It grows with valve size. A thicker lining slows permeation but raises operating torque, so ask for the specified thickness at your DN.
• Seat: PTFE is harder than rubber. It gives tighter shutoff, but it needs more torque and careful bolting.
• Disc: Options include a metal core with full PTFE encasement or a bare alloy disc. Pick the encased disc whenever the media attacks metal.

How Do PTFE Lined Valve Temperature and Pressure Ratings Compare?

Most lined butterfly valves run at PN10 or PN16 and from about -20°C to 150°C, but each design has its own limits. Rating follows the casting, trim and lining, not the body style alone.

• Mid-line versus dead-end: Lug end-of-line ratings fall below mid-line ratings. Confirm the dead-end pressure with the maker.
• Temperature: PTFE softens as temperature rises, so allowable pressure drops. Request the pressure-temperature curve for your valve before ordering.
• Vacuum: State vacuum duty on the order, because the lining needs support against collapse.

Which Sizes and Standards Apply to PTFE Lined Butterfly Valves?

API 609 and ISO 5752 set the design and face-to-face rules, and API 609 spans NPS 2 to 60. Category A covers Class 125 and 150 bolt patterns, while Category B covers Class 150 and 300.

ISO 5752 lets you replace one maker’s valve with another without cutting the pipe. Size the valve by matching its nominal diameter to the pipe. After that, confirm that the open disc clears the pipe lining, because a lined pipeline has a smaller bore than bare steel pipe.

Engineers should read butterfly valve specifications for flange drilling, face-to-face series and ISO 5211 actuator mounting.

Wafer and lug bodies typically cover DN50 to DN600. Above DN600, disc stability favours a double-flanged body. Always confirm the exact size range with the maker.

What Are the Common Applications of PTFE Lined Butterfly Valves?

A lined butterfly valve is used where the medium eats away at the metals, including chemicals, water treatment plants, and petrochemicals.

• Chemical: Use it on chlor-alkali brine, acid transfer and pharmaceutical intermediate lines. Youfumi lists these industries on its project pages.
• Water treatment: Use it on dosing lines for hypochlorite, ferric chloride, acid and caustic. For plain potable water, an EPDM seat costs less.
• Petrochemical: Use it on refining and coal chemical process lines. Pick a lug body at pump suction, where crews remove pipe often.

What Installation and Maintenance Tips Protect the Lining?

Proper installation and maintenance protect the lining from impact, debris, pipe misalignment, welding heat, over-torque or incompatible operation.

Protect the lining by following the guidelines below:

To start, open the disc slightly, centre the valve and tighten the bolts in a cross pattern to protect the lining.

1. Prepare: Check the pipe bore and flange faces first. Remove weld spatter and dirt that can cut the lining.
2. Tighten: Tighten in stages, then retighten after the first thermal cycle, because PTFE creeps under load.
3. Support: Support the pipe when you remove one side of a lug valve.
4. Actuate: Size the actuator with at least 25% margin over breakaway torque.
5. Inspect: Check the lining and stem seal at each shutdown for blisters, cracks and leaks.
6. Store: Keep flange protectors on each lined valve until installation.
7. Align: Centre the valve between flanges before you tighten. A shifted valve pinches the lining and raises torque.

Conclusion

Before purchasing PTFE lined valves for your project, always read butterfly valve specifications to make sure that they are aligned with your requirements. Check the lining, the pressure-temperature curve, and the API 609 and ISO 5752 dimensions before you order.

For pump and end-of-line duty, start with the lug-type lined butterfly valve. For aggressive media, specify the fully lined butterfly valve.

Lug Butterfly Valve

Compact Design; Investment Casting; Lining Virgin PTFE; Bubble Tight Shutoff; High CV Value; Direct Mount Actuation; Maintenance-free; Wide Sealing Face; High Permeation Resistance

View Product Details

Youfumi backs these choices with CE, ISO 9001 and ISO 14001 certificates, patents ZL98217159.5 and ZL99333577.2, and CNPC and SINOPEC supplier status.

Frequently Asked Questions

When should I use a PTFE lined valve?

Use a lined butterfly valve when the media is corrosive, such as strong acids, chlorine or caustic. It also suits lines that need quarter-turn isolation in mid to large pipe sizes.

How do I size a lined butterfly valve?

Match the nominal diameter to the pipe bore. Check that the open disc clears the pipe lining. Then confirm flange drilling, face-to-face series and actuator torque on the datasheet.

What temperature and pressure can a lined butterfly valve handle?

Most designs can handle PN10 or PN16 and up to about 150°C. Allowable pressure drops as temperature rises, so request the pressure-temperature curve for your exact valve.