Metal-Seated Ball Valve Design and Applications

Why Metal Seats?

Soft-seated ball valves use PTFE or similar polymers that degrade above 200°C or in abrasive service. Metal-seated ball valves provide reliable shut-off at high temperatures, with abrasive media, and in services where polymer contamination is unacceptable.

Metal Seat Materials and Coatings

• Stellite (cobalt alloy) overlay: excellent hardness and corrosion resistance

• Tungsten carbide (WC): extreme hardness for abrasive and erosive service

• Inconel seats for high-temperature, high-pressure hydrogen service

• Hard chrome plating: cost-effective for moderate temperature applications

Seat Geometry and Sealing Mechanism

Metal-seated ball valves rely on a precision-lapped interface between ball and seat ring. Seating force is generated by spring loading the seats against the ball. The spring preload must overcome system pressure trying to push the seat away from the ball.

Temperature Range

• Standard metal-seated: −29°C to +425°C

• High-temperature service: up to 650°C with Alloy 625 or ceramic components

• Fire-safe designs retain metal-to-metal contact when soft seals burn away

• Cryogenic service down to −196°C with extended bonnet

Typical Applications

Metal-seated ball valves are standard in: steam systems, hot oil units, sulfur plants, FCC catalyst transfer, coker units, and high-temperature gas pipelines. They provide reliable isolation where soft seats would be immediately destroyed by process conditions.