Ball valve seat materials are primarily categorized as metal and non-metal. Their selection should be based on comprehensive considerations of media characteristics, temperature, pressure, and corrosion resistance. The following are the main material classifications and technical characteristics:
1. Metal Seat Materials
Stainless Steel Series
Basic Type: Austenitic stainless steels such as 304 and 316L are resistant to mildly corrosive media and high temperatures (≤400°C), suitable for water, steam, and general chemical fluids.
Specialty Alloys: Hastelloy and Monel (such as Monel 400) are resistant to highly corrosive media such as hydrofluoric acid and high-temperature hydrogen fluoride.
Duplex Steel (such as S31803 and S32750): Features a combination of austenitic and ferritic structures, resists chloride stress corrosion, and is suitable for acidic environments containing chloride ions. Cemented Carbide
Made by sintering a hard phase such as tungsten carbide/titanium with a cobalt/nickel binder phase, its characteristics include:
Hardness ≥ 85 HRA, extremely wear-resistant, and resistant to erosion by media containing solid particles;
Temperature resistance exceeding 550°C, and excellent high-pressure sealing stability (≥ 42 MPa);
Highly expensive, it is primarily used in demanding applications such as coal chemical industry and oil and gas pipelines.
2. Non-metallic valve seat materials
(1) Polymer-based materials
| Material Type | Applicable temperature | Features and limitations | Applications |
|---|---|---|---|
| PTFE | -196~260℃ | Strong chemical inertness and low friction coefficient (0.02–0.04), but prone to cold flow deformation | Corrosive chemicals, low-temperature media |
| Reinforced PTFE | -100~100℃ | Adding glass fiber/graphite to improve compressive strength and wear resistance | Universal seal for medium and low pressure ball valves |
| PEEK | -70~260℃ | High strength retention at high temperatures, resistant to steam and hydrocarbon solvents, and more expensive than PTFE | High-pressure and high-temperature valve seats in the petroleum industry |
| EPDM | -28~120℃ | Ozone/phosphate ester resistant, avoid contact with petroleum solvents | HVAC systems, water treatment |
(2) Engineering Elastomers
Nitrile-butadiene rubber (NBR): Excellent oil resistance (-18°C to 100°C), suitable for fuel and lubricating oil media, but poor oxidation resistance.
Polyurethane (PU): Offers a balance of high elasticity and wear resistance, commonly used for valve seat cushions in mining slurry systems.
3. Key Technical Indicators for Selection
Temperature Adaptability: Metal Valve Seat > PEEK > PTFE > Rubber (Carbide withstands 550°C, PTFE is limited to 260°C);
Corrosion Resistance:
Strong Acids/Alkalis: PTFE and Hastelloy are preferred;
Chlorine-Containing Media: Duplex Steel or Monel.
Wear Resistance Requirements: Carbide or polyurethane composite materials offer a 3–5x longer lifespan when used with slurry/catalyst particles.
