A trunnion mounted ball valve is a type of industrial valve that uses a trunnion, or a fixed shaft, to support the ball. This design provides increased stability and reduces the operating torque required to turn the valve compared to floating ball valves. Trunnion mounted ball valves are commonly used in high-pressure and large-diameter pipeline applications. Here are some key features and characteristics of trunnion mounted ball valves:
- Ball Design: The valve has a spherical or cylindrical-shaped ball with a hole (port) through its center. When the valve is open, the port aligns with the pipeline to allow flow, and when closed, the ball rotates to block the flow.
- Trunnion Mounting: The ball in a trunnion mounted ball valve is supported by a fixed shaft or trunnion at the top and bottom of the ball. This trunnion design provides additional support and stability to the ball, especially in larger valve sizes and high-pressure applications.
- Reduced Operating Torque: The trunnion-mounted design reduces the operating torque required to turn the valve, making it easier to operate and providing more precise control.
- Sealing Mechanism: Trunnion mounted ball valves can have both soft (e.g., PTFE) and metal-to-metal seat sealing options. The choice of sealing material depends on the type of fluid, temperature, and pressure requirements of the application.
- Bearing Mechanism: Bearings are often used at the trunnion points to reduce friction and wear, ensuring smooth and reliable operation over an extended period.
- Two or Three-Piece Construction: Trunnion mounted ball valves come in two-piece or three-piece body constructions. In a three-piece design, the center section can be removed for maintenance or repair without affecting the pipeline.
- Full and Reduced Bore Designs: Trunnion mounted ball valves are available in both full bore and reduced bore configurations. Full bore designs have a larger ball opening, minimizing pressure drop and allowing for pigging (cleaning) of the pipeline.
- Fire-Safe Design: Some trunnion mounted ball valves are designed to meet fire-safe requirements, ensuring their integrity in case of a fire.
- High-Pressure Applications: These valves are suitable for high-pressure applications, including oil and gas pipelines, petrochemical plants, and power generation.
- Top-Entry and Side-Entry Configurations: Trunnion mounted ball valves can be designed with top-entry or side-entry configurations. Top-entry valves allow easy access to internal components for maintenance without removing the valve from the pipeline.
- Automation Compatibility: Trunnion mounted ball valves can be easily automated using various actuation methods, including electric, pneumatic, or hydraulic actuators, for remote and precise control.
- API Standards: These valves are often designed and manufactured in accordance with industry standards, such as API 6D or API 608, depending on the application and industry requirements.
Trunnion mounted ball valves are favored in applications where high performance, durability, and precise flow control are essential. Proper selection based on the specific requirements of the application, along with regular maintenance, ensures their reliable and efficient operation in industrial processes.