Metal-seated ball valves vs. soft-seated valves

The selection of ball valves presents numerous options, with key considerations including construction material, size, design (double block and bleed, V-port, 1, 2, or 3 pieces), and seat types. One significant consideration during valve selection is the process conditions: Is the fluid abrasive? Corrosive? What are the flow pressure and temperature? Does the valve require bubble-tight shutoff? Once these factors are known, selecting the best valve for the application becomes more straightforward. Metal-seated valves and soft-seated valves have distinct properties. This blog explains metal-seated and soft-seated ball valves, their pros and cons, and common applications.

What is a metal-seated ball valve?

A metal-seated valve utilizes a seat made of metallic material, chosen based on the specific application, such as oil and gas, chemical processing, and power plants. For example, a copper alloy seat is suitable for low-pressure applications, while nickel-based valves excel with corrosive fluids. Metal-seated valves can withstand harsh conditions, including acids, abrasives, heat, erosion, hydraulic shock, and high pressure. Although more expensive than soft-seated valves, they are less prone to leakage.

Features and benefits of metal-seated ball valves:

• Metallic Seat: Composed of materials like stainless steel, carbon steel, cobalt alloys, providing resistance to high temperatures and impact damage.
• Abrasion and Corrosion Resistance: Ideal for fluids with solid particles or corrosive properties, preventing degradation of the valve seat.
• Durability and Cost-Effectiveness: Long service life due to corrosion and erosion resistance, reducing replacement and maintenance costs.
• Wide Temperature and Pressure Range: Capable of withstanding extreme pressures and temperatures, suitable for high-performance applications.
• Leak-Proof: Utilizes a hard seat material, creating an effective seal with the ball, preventing pressure loss and leakage.

Common applications of metal-seated ball valves:

• Power Plants: Controlling steam and hot fluid flow in steam power plants.
• Chemical Processing: Resisting corrosion in chemical processing applications.
• High-Pressure and High-Temperature Applications: Used in desalination and wastewater management.
• Mining Industries: Handling abrasive slurry prone to wear.
• Food and Beverage Processing: Ensuring hygiene in processing.
• Oil and Gas Transportation: Facilitating the transportation of oil and gas.
• Pharmaceuticals: Ensuring safety in pharmaceutical applications.

Soft-seated ball valves

As the name implies, a soft-seated ball valve employs a seat made of soft/non-metallic materials like Delrin, PTFE, and PEEK. These materials are designed for low to medium pressure and are suitable for low temperatures. Soft-seated valves offer enhanced sealing compared to metal-seated valves when properly selected. However, in conditions involving dirty process fluids and abrasives, the soft material may break, causing leakage. These valves are more budget-friendly compared to their metal-seated counterparts.

Features and benefits of soft-seated ball valves:

• Improved Sealing: Enhanced sealing with the soft seat material adhering better to the ball.
• Vibration Absorption: Better absorption of shocks and vibrations, reducing damage risks.
• Ease of Installation: Simple installation due to seat material flexibility, minimizing the need for additional adjustments.
• Lower Initial Cost: Cost-effective option with the use of less expensive materials.

Common applications of soft-seated ball valves:

• Water and Wastewater Transportation: Perfect sealing and corrosion resistance.
• Chemical Processing: Resisting toxic chemicals and corrosion.
• Pharmaceuticals and Food Processing: Preventing product contamination.
• Other Low-Pressure and Low-Temperature Applications.

Understanding the differences between metal-seated and soft-seated ball valves is crucial for making informed decisions based on specific application requirements.