Butterfly Valve Seat Material Selection Guide: 5 Mainstream Materials and Chemical Compatibility

Selecting the right seat material for a Butterfly Valve is one of the most critical decisions in fluid handling system design. In chemical processing, OEM equipment, and EPC projects, the valve seat is often the first component to fail if material compatibility is overlooked—leading to leakage, unplanned downtime, and potential safety incidents. While EPDM, CSM, FKM, and PTFE are widely used, a broader portfolio of elastomers exists to address specific combinations of temperature, chemical attack, and mechanical demands. This guide profiles five mainstream seat materials—from cost-effective general-purpose rubbers to high-performance fluoroelastomers and PTFE—comparing their chemical resistance, temperature limits, and best-fit applications, and provides a quick-reference compatibility matrix for common industrial acids and alkalis.

1. EPDM (Ethylene Propylene Diene Monomer)

Key Properties

• Excellent resistance to hot water and steam

• Outstanding ozone and aging resistance

• Resistant to most inorganic acids and alkalis

• Low cost, most widely used

Suitable Media
✔ Water, drinking water, seawater, wastewater
✔ Sodium hydroxide (NaOH), potassium hydroxide (KOH)
✔ Dilute sulfuric acid, dilute phosphoric acid

Not Recommended For
✘ Petroleum products, hydraulic oils, gasoline
✘ Aromatic hydrocarbons

Temperature Range
-20 °C to 120 °C (-4 °F to 248 °F); special grades up to 140 °C (284 °F)

Typical Applications
Water supply and treatment, cooling water circuits, dilute acid/alkali service, potable water systems.

2. CSM (Chlorosulfonated Polyethylene, formerly Hypalon®)

Key Properties

• Exceptional ozone and UV resistance

• Excellent chemical and oxidation resistance

• Good acid and alkali resistance

Suitable Media
✔ Acids, alkalis, sodium hypochlorite, brine
✔ Ozone environments, outdoor chemical equipment

Not Recommended For
✘ Aromatic hydrocarbons
✘ Some organic solvents

Temperature Range
-20 °C to 120 °C (-4 °F to 248 °F)

Typical Applications
Chemical plants, wastewater treatment, bleaching systems, chlor-alkali industry, outdoor corrosive environments.

3. CIIR (Chlorinated Isobutylene Isoprene Rubber, Chlorobutyl)

Key Properties

• Excellent acid resistance, outstanding ozone and aging resistance

• Extremely low gas permeability, good steam resistance

Suitable Media
✔ Dilute acids, some concentrated acids, deionized water
✔ Hot water, steam, vacuum systems

Not Recommended For
✘ Petroleum-based fluids, aromatic hydrocarbons
✘ Organic solvents

Temperature Range
-20 °C to 130 °C (-4 °F to 266 °F)

Typical Applications
Pharmaceutical, food, ultrapure water systems, clean steam, and chemical vacuum/acid service.

4. FKM (Fluoroelastomer, Viton®)

Key Properties

• Excellent high-temperature and oil resistance

• Resistant to most acids and organic solvents

Suitable Media
✔ Concentrated sulfuric acid (certain concentrations), phosphoric acid, organic acids
✔ Petroleum products, aromatic hydrocarbons, vacuum systems

Not Recommended For
✘ Hot concentrated caustic soda, amines
✘ Ketones

Temperature Range
-10 °C to 200 °C (14 °F to 392 °F)

Typical Applications
High-temperature oils and chemicals, petrochemicals, solvent transfer, high-vacuum systems.

5. PTFE (Polytetrafluoroethylene)

Although not an elastomer, PTFE is extensively used in Butterfly Valve Seats as the benchmark for chemical resistance.

Key Properties

• Virtually universal chemical resistance

• Extremely low friction coefficient, non-aging

• FDA-compliant food-grade material

Suitable Media
✔ Hydrochloric acid, sulfuric acid, nitric acid, sodium hydroxide, sodium hypochlorite
✔ Chlorine, strong oxidizers, organic solvents, ultrapure water

Temperature Range
-40 °C to 180 °C (-40 °F to 356 °F); some grades go higher

Typical Applications
Highly corrosive chemicals, high-purity media, food and pharmaceutical processes, severe chemical service.

Recommended Seat Materials for Common Acids and Alkalis