In the world of fluid flow control, butterfly valves are renowned for their compact design, cost-effectiveness, and quick operation. But one critical component often overlooked is the valve seat—the inner lining that ensures tight shutoff and prevents leaks.

The seat forms the seal between the disc and the valve body. Choosing the right seat material is vital to the valve's resistance to temperature, pressure, corrosion, and chemical compatibility. A poor material choice can lead to premature failure, maintenance issues, or even operational downtime.

At Aik Soon Hardware Pte Ltd, we stock and supply high-performance butterfly valves engineered for demanding marine and industrial conditions across Singapore and Southeast Asia. In this guide, we dive into the four most commonly used seat materials: EPDM, NBR, PTFE, and Viton—to help you make an informed decision.

1. EPDM (Ethylene Propylene Diene Monomer)

Overview:
EPDM is a synthetic elastomer widely used in water-based systems. It offers excellent flexibility, sealing performance, and weather resistance.

Key Characteristics:

• Temperature Range: -30°C to +130°C (intermittently up to 150°C)

• Hardness (Shore A): 65–80

• Chemical Resistance: Excellent against water, steam, dilute acids, alkalis, and alcohols

Pros:

• Great for both cold and hot water systems

• High resistance to UV, ozone, and aging

• Non-toxic and suitable for potable water applications

• Cost-effective and readily available

Cons:

• Poor resistance to petroleum-based fluids, hydrocarbons, and solvents

• May swell or degrade in oil-rich environments

Best Applications:

• HVAC systems

• Water treatment plants

• Marine systems involving fresh or seawater

• Food and beverage (non-oily media)

Not recommended for: Oil pipelines, fuel systems, or systems involving grease or solvents.

2. NBR (Nitrile Butadiene Rubber)

Overview:
Also known as Buna-N, NBR is another synthetic rubber but is specially formulated for oil resistance.

Key Characteristics:

• Temperature Range: -20°C to +90°C (up to 100°C for short durations)

• Hardness (Shore A): 70–85

• Chemical Resistance: Excellent to oils, lubricants, fuels, and many hydrocarbons

Pros:

• High resistance to mineral oils, diesel, and synthetic fluids

• Good compression set and tear resistance

• Economical for oil-heavy applications

Cons:

• Limited resistance to weathering, ozone, and sunlight

• Degrades in strong oxidising agents and polar solvents

• Less suitable for water-based media at high temperatures

Best Applications:

• Oil & gas pipelines

• Diesel engine systems

• Hydraulic fluid systems

• Fuel transfer and chemical tanks

Not recommended for: Outdoor installations with direct UV exposure or applications involving steam or chlorinated water.

3. PTFE (Polytetrafluoroethylene)

Overview:
PTFE, commonly known by the brand name Teflon™, is a non-elastomeric thermoplastic material known for its chemical inertness and low friction properties.

Key Characteristics:

• Temperature Range: -200°C to +200°C

• Hardness (Shore D): ~55

• Chemical Resistance: Resistant to almost all corrosive chemicals, including acids, alkalis, solvents, and oxidizers

Pros:

• Exceptional chemical compatibility

• Non-stick surface prevents media buildup

• Performs well in both low and high temperatures

• Suitable for hygienic applications (FDA compliant variants available)

Cons:

• More expensive than rubber seat options

• Lacks elasticity—relies on precise installation and flange alignment

• Can experience cold flow (creep) under long-term compression

Best Applications:

• Chemical processing (acids, solvents, aggressive media)

• Food & pharmaceutical industries

• High-purity water systems

• Marine scrubber systems with corrosive exhaust streams

Not recommended for: Systems requiring a soft, forgiving seal in low-pressure applications where elasticity is needed.

4. Viton® (Fluorocarbon Rubber)

Overview:
Viton, a brand name for fluoroelastomer developed by DuPont, is prized for its exceptional chemical resistance and thermal stability.

Key Characteristics:

• Temperature Range: -10°C to +200°C

• Hardness (Shore A): 75–90

• Chemical Resistance: Outstanding resistance to oils, fuels, acids, and solvents

Pros:

• Withstands aggressive chemicals, including aromatic hydrocarbons

• Excellent high-temperature performance

• Good compression and aging resistance

• Performs well in vacuum and high-pressure applications

Cons:

• One of the most expensive seat materials

• Limited flexibility in extremely cold temperatures

• Sensitive to steam over 120°C for prolonged periods

Best Applications:

• Petrochemical pipelines

• Aggressive chemical media in marine or industrial plants

• Fuel systems and loading terminals

• High-temperature fluid transport systems

Not recommended for: Budget-conscious projects or low-temperature outdoor applications.

Side-by-Side Comparison Table

Conclusion: The Right Seat Material Saves Cost and Prevents Failure

Choosing the right butterfly valve seat material can dramatically affect the lifespan, safety, and efficiency of your fluid system. Whether you're operating a desalination plant, managing chemical pipelines, or maintaining a ship's ballast system, material compatibility is non-negotiable.

At Aik Soon Hardware Pte Ltd, we don’t just sell valves—we provide expert guidance and technical support to help you select the optimal valve configuration for your unique application. With decades of experience in the marine and industrial sector, we are Singapore’s trusted partner for reliable valve solutions.