Trunnion vs. Floating Ball Valves: Key Differences

When selecting an industrial ball valve, one of the first decisions is whether a floating ball valve or trunnion mounted ball valve is better suited to the application. Both designs use a quarter-turn ball to provide reliable flow isolation, but their internal support structures differ significantly.

A floating ball valve relies on line pressure to push the ball against the downstream seat, while a trunnion mounted design uses a fixed lower and upper support system to reduce ball movement and operating torque. The right choice depends on valve size, pressure rating, media, temperature and operating conditions.

Key Takeaways

• Floating ball valves are commonly used for smaller and general industrial applications.
• Trunnion mounted ball valves are well suited to larger sizes and higher-pressure service.
• Trunnion designs generally require lower operating torque at larger sizes.
• Valve selection should consider pressure, size, media, temperature and operating frequency.

What Is a Floating Ball Valve?

In a floating ball valve, the ball is not mechanically fixed at the bottom. Instead, the ball can move slightly under pressure.

When the valve is closed, upstream pressure pushes the ball toward the downstream seat, helping create a tight seal.

This relatively simple construction makes floating ball valves suitable for many general industrial applications where valve size and pressure requirements are moderate.

However, as valve size and pressure increase, the force acting on the ball and seats also increases. This can result in higher operating torque and greater demands on the valve actuator.

What Is a Trunnion Mounted Ball Valve?

A trunnion mounted ball valve supports the ball with a fixed trunnion system. The ball does not move freely toward the downstream seat in the same way as a floating design.

This arrangement helps reduce the force required to rotate the ball, particularly in larger valves and higher-pressure applications.

Trunnion mounted ball valves are therefore widely used in applications such as oil and gas pipelines, gas transmission, petrochemical facilities and other demanding process systems.

For projects requiring larger sizes or higher pressure classes, a trunnion mounted ball valve can provide a practical combination of reliable isolation and manageable operating torque.

Trunnion vs. Floating Ball Valves

These are general selection guidelines rather than strict limits. The appropriate design depends on the actual valve specification and service conditions.

When Should You Choose a Trunnion Mounted Ball Valve?

A trunnion mounted design may be considered when the project involves:

• Large pipeline diameters
• High pressure ratings
• Frequent valve operation
• Long-distance oil and gas pipelines
• Natural gas transmission
• Petrochemical processing
• Applications requiring lower operating torque

For example, Kaiwei's trunnion mounted ball valve range includes different sizes, pressure classes and configurations for demanding industrial applications.

For projects requiring a more specialized design, you can also review Kaiwei's [industrial ball valves] to compare different ball valve configurations.

When Is a Floating Ball Valve More Suitable?

A floating design may be appropriate when the application involves:

• Smaller valve sizes
• Moderate pressure
• General process isolation
• Water and utility systems
• Less demanding operating conditions
• Applications where a simpler valve construction is preferred

The important point is that floating ball valves should not simply be selected because they have a simpler design. Pressure, temperature, media and valve size still need to be checked against the manufacturer's technical specifications.

How Do You Choose Between Them?

A practical selection process starts with five questions:

1. What Is the Valve Size?

Valve size affects the forces acting on the ball and seats. Larger pipelines often require a trunnion mounted design.

2. What Is the Operating Pressure?

Higher pressure can increase the force acting on the ball and therefore influence operating torque and seat loading.

3. What Is the Medium?

Gas, oil, water and corrosive or abrasive media may require different body, seat and sealing materials.

4. How Often Will the Valve Operate?

High-cycle applications can place additional demands on seats, seals and operating components.

5. What Are the Project Standards?

API, ASME and other applicable standards should be confirmed before selecting the final valve configuration.

Final Considerations

There is no universal answer to whether a floating or trunnion mounted ball valve is better. The correct design depends on the combination of size, pressure, temperature, media, sealing requirements and operating conditions.

Floating ball valves can be suitable for many general industrial services, while trunnion mounted designs are commonly selected for larger and higher-pressure applications.

Before choosing a ball-support design, confirm whether a ball valve is the right industrial isolation valve for the complete duty.

For a broader comparison of available designs, explore Kaiwei's industrial ball valves and select the configuration according to your project requirements.

If the required valve family has not yet been decided, first compare gate, globe, ball, butterfly, and check valves by function and operating conditions.

Need help selecting a ball valve? Contact Kaiwei with your required size, pressure class, media and operating conditions for a suitable configuration.