Description

A trunnion ball valve is a quarter-turn valve designed for high-pressure and large-diameter applications. Unlike a “floating” ball valve, its spherical ball is not free-floating. Instead, it is fixed in place by a mechanical support system consisting of a top stem and a bottom shaft called a “trunnion.”This design supports the ball, absorbing the pressure from the fluid, which significantly reduces the operating torque required to turn the valve and minimizes wear on the valve seats. The seats, often spring-loaded, are pushe d against the fixed ball to create a tight seal, making this valve ideal for demanding services. Available in A105, A182/F316 steel, it is designed for industrial applications according to ASME B16.34 and API 6D standards

Types and Standards

Trunnion ball valves are primarily classified by their body construction, with each design serving specific maintenance and application needs.

• Side-Entry/Split Body: The valve body is made of two or three bolted pieces, allowing for easy access to the internal components for maintenance or repair without removing the entire valve from the pipeline.
• Top-Entry: The valve body is made of two or three bolted pieces, allowing for easy access to the internal components for maintenance or repair without removing the entire valve from the pipeline.
• Fully Welded: The valve body is fully welded, eliminating potential leak paths. This robust design is preferred for critical applica tions in oil and gas pipelines where no maintenance is anticipated for long periods.

ASME and API Standards

• ASME B16.34: This standard governs the design, pressure-temperature ratings, and materials for valves, including trunnion ball valves. It ensures that the valve’s construction is suitable for its intended service.
• API 6D: This is a key specification for pipeline valves (including ball valves), covering design, manufacturing, testing, and documentation requirements for petroleum and natural gas pipeline systems. It specifies the critical dimensions and features for trunnion valves.