Our range includes PTFE lined butterfly valves (full corrosion resistance for aggressive media), PFA lined butterfly valves (high-temperature chemical stability), and split-body lined designs (easy maintenance and seat replacement). All are manufactured to API 609, ASME B16.34, and ISO 5752 standards with virgin PTFE or PFA linings, dual-shaft sealing systems, and FDA-compliant materials for demanding chemical processing, pharmaceutical, food and beverage, and high-concentration acid applications.

Our high pressure angle valves are trusted across diverse industries for their durability, erosion resistance, and reliable performance under extreme pressure drops.

You need a corrosion-resistant butterfly valve for aggressive chemicals, but the options – concentric, double-eccentric, wafer, flanged – can be confusing. The wrong choice leads to liner collapse, poor shut-off, or chemical attack. Here’s exactly when to pick each type.

For low-cost, general chemical service with bubble-tight shut-off → Concentric (Zero-Offset) PTFE Lined Butterfly Valve. For higher pressures, frequent cycling, and better wear life → Double-Eccentric PTFE Lined Butterfly Valve. For tight spaces, light weight, and low installation cost → Wafer Type PTFE Lined Butterfly Valve. For large diameters, dead-end service, or high pressure → Flanged Type PTFE Lined Butterfly Valve.

Figure 1: Four main PTFE lined butterfly valve configurations – each optimised for a specific corrosive service window.

Real-world lesson: A chemical plant once installed a standard concentric PTFE lined wafer valve on a concentrated sulfuric acid line with vacuum conditions. Within two weeks, the liner collapsed into the flow path, causing a full plant shutdown. The problem: the push-in liner was not rated for vacuum. We replaced it with a flanged, fully-lined double-eccentric valve with a one-piece PTFE seat and stainless steel disc – and the line ran without issues for five years. Never ignore vacuum rating and lining construction.

What You Really Need to Know Before Choosing

Before we dive in, you need to understand four critical factors for PTFE lined butterfly valves: chemical compatibility (PTFE vs. PFA vs. FEP), temperature & pressure limits (PTFE cold-flows under pressure above ~100°C), vacuum resistance (some liners collapse under negative pressure), and shut-off leakage class (PTFE seats typically achieve ANSI/FCI 70-2 Class VI). Keep these in mind – they will decide your long-term reliability.

1. Concentric (Zero-Offset) PTFE Lined Butterfly Valve – The Workhorse for General Chemical Service

How It Works

The valve stem centre, disc centre, and body centre are perfectly aligned (zero offset). A resilient PTFE seat is molded or inserted into the body. When the disc rotates 90°, it compresses against the seat to provide bubble-tight shut-off. The PTFE lining covers all wetted surfaces – body, disc, and stem – protecting the metal substrate from aggressive fluids. Designs follow API 609 Category A and MSS SP-67 .

When I Recommend It

• General chemical transfer – hydrochloric acid, sulfuric acid (up to 80% concentration), caustic soda, and salt water.
• Water treatment & desalination – where corrosion resistance is needed without high pressure or frequent cycling.
• Low to medium pressure systems (PN6–PN16, up to 150 psi) where installation cost is a priority.
• On-off service with infrequent operation – the PTFE seat will last for years if not cycled daily.

Where It Falls Short

The concentric design creates high seating friction, which wears the PTFE seat faster under frequent cycling. It also has limited pressure recovery and is not suitable for high differential pressures (ΔP > 10 bar). Most critically, many concentric designs cannot handle full vacuum – the liner can be sucked out of the body. Always specify “vacuum service” and request a one-piece seat with disc encapsulation if you need vacuum capability.

2. Double-Eccentric (High-Performance) PTFE Lined Butterfly Valve – For Tough Cyclic & High-Pressure Duties

How It Works

The stem is offset in two planes: behind the disc centre and to one side of the body centre. This “double offset” lifts the disc off the seat immediately upon opening, virtually eliminating rubbing and friction. The result is a much longer seat life, lower torque, and the ability to handle higher pressures (up to PN25 / 300 psi) and temperatures. Many designs also feature a reinforced PTFE seat with an elastomer backing for better resilience. Standards: API 609 Category B , ISO 5752 .

When You Want This One

• Frequent cycling / modulating service – where a concentric valve would wear out the seat in months.
• Higher system pressures (up to 300 psi / PN25) – oil & gas, chemical plant main headers.
• Slurry or abrasive media – the “cam-like” action clears debris away from the seat.
• Vacuum service – most double-eccentric designs come with fully encapsulated PTFE discs and seats that resist collapse down to full vacuum (1 torr).

The Trade-Off

Double-eccentric valves are more expensive – typically 30-50% higher than concentric designs. They also have a slightly larger face-to-face dimension (per ISO 5752) and may require stronger actuators due to the initial breakaway torque. However, for demanding services, the longer lifecycle and reliability more than justify the cost.

3. Wafer Type PTFE Lined Butterfly Valve – Compact, Lightweight, Low-Cost

How It Works

The valve body has no integral flanges. It is designed to be clamped between two pipe flanges using longer stud bolts. The PTFE lining extends over the full face of the valve, acting as a gasket against the pipe flanges. Wafer designs are shorter face-to-face (e.g., EN 558 Series 20) and much lighter than flanged valves. They are available in both concentric and double-eccentric configurations.

When You Reach for This One

• Space-constrained installations – skid systems, chemical dosing cabinets, and modular plants.
• Cost-sensitive projects – wafer valves are 20-30% cheaper than flanged equivalents.
• Lightweight piping systems – where heavy flanged valves would require additional supports.
• Clean, non-abrasive liquids – water-based chemicals, mild acids, and alkalis.

Limitation

You cannot perform dead-end service (removing downstream piping while the valve is closed) because the valve is clamped between two flanges – the downstream flange is required to hold the valve in place. Also, wafer valves are more sensitive to misalignment during installation; uneven bolt torque can distort the PTFE liner and cause leakage. Not recommended for vacuum service unless the manufacturer explicitly states vacuum capability.

4. Flanged Type PTFE Lined Butterfly Valve – Maximum Integrity for Large Lines & High Pressure

How It Works

The valve body has integral flanges at both ends (e.g., ASME B16.5 Class 150, PN10/16/25). Flanged designs provide robust, leak-free connections. The PTFE lining is typically injection-molded or compression-molded directly onto the body and disc, creating a thick, pinhole-free barrier. Many flanged valves also incorporate a “lip seal” design that isolates the stem from the media. Standards: ASME B16.34 , EN 12516 .

When You Absolutely Need This Valve

• Large diameters (DN200 / 8″ and above) – flanged valves provide the structural strength for heavy piping.
• High-pressure or high-temperature service – up to PN25 (300 psi) and 200°C with PFA lining.
• Dead-end service – you can remove downstream piping while the valve remains pressurised upstream (especially with lugged flanged designs).
• Severe chemical duty – 98% sulfuric acid, hydrochloric acid, chlorine, bromine, and hazardous fluids where zero permeation is required.

One Limitation

Flanged valves are heavier, more expensive, and have longer face-to-face dimensions (EN 558 Series 13 or 14). Installation takes longer due to the number of flange bolts. However, for critical services, the added safety and maintainability are well worth it.

Critical safety note: For toxic or highly corrosive fluids (e.g., chlorine, anhydrous HCl), always use a fully flanged, fully lined valve with a secondary stem seal per API 609 and ISO 15848 (fugitive emissions). Never use wafer valves for lethal service – the clamped connection is a potential leak path.

Quick Comparison Table: PTFE Lined Butterfly Valves

Feature	Concentric (Zero-Offset)	Double-Eccentric	Wafer Type	Flanged Type
Primary Use	General chemical, water treatment, low-moderate pressure	High cycling, high pressure, abrasives, vacuum	Space & cost-sensitive, clean fluids	Large diameters, high pressure, lethal service, dead-end
Pressure Rating	PN6 – PN16 (150 psi max)	PN10 – PN25 (300 psi)	PN6 – PN16	PN10 – PN25 (ASME Class 150/300)
Temperature Range	-20°C to +180°C (PTFE)	-20°C to +200°C (PFA)	-20°C to +180°C	-29°C to +230°C (PFA)
Vacuum Rating	Not standard (liner collapse risk) – specify “vacuum”	Full vacuum (1 torr) with encapsulated disc	Poor – not recommended	Full vacuum (with one-piece seat)
Face-to-Face Standard	EN 558 Series 20 (wafer)	API 609 / ISO 5752	EN 558 Series 20	EN 558 Series 13 or 14
Relative Cost	$	$$$	$ (cheapest)	$$

Making the Right Choice – A Practical Decision Framework

Need a low-cost, general purpose valve for acids or alkalis with bubble-tight shut-off and no vacuum? → Concentric PTFE Lined Butterfly Valve (Wafer type) .

Facing frequent cycling, high pressures, or vacuum – and you want longer seat life? → Double-Eccentric PTFE Lined Butterfly Valve .

Have limited space and a tight budget for clean chemical service? → Wafer Type (any eccentricity) .

Handling large diameters, high pressure, lethal or hazardous fluids , or need dead-end service? → Flanged Type PTFE Lined Butterfly Valve .

Always verify the liner material (PTFE vs. PFA vs. FEP) against your chemical concentration and temperature. For aggressive oxidisers like chlorine or bromine, specify PFA lining because it is less permeable. Never assume a wafer valve is vacuum-capable – ask for a vacuum test per ISO 9393 . And remember: PTFE creeps under sustained high pressure and temperature; a flanged double-eccentric design will outlast a concentric wafer valve by years in tough conditions.

Pro tip: For modulating (throttling) service, avoid concentric PTFE lined valves – the high breakaway torque and stiction cause poor control. Use a double-eccentric valve with a pneumatic positioner. Always provide the manufacturer with your exact temperature, pressure, vacuum level, and chemical composition – they can then recommend the correct liner thickness, disc material (fully encapsulated vs. solid PTFE), and seat design.