Floating Ball Valve vs. Trunnion Mounted Ball Valve

When selecting the right ball valve for your system, understanding the differences between a floating ball valve and a trunnion-mounted (fixed ball) valve is critical. These two valve types serve different pressure ranges, bore sizes, and media conditions. In this article, we’ll break down the design, functionality, application scenarios, and performance of each—so you can make an informed decision for your project or facility.

1. Structural Design

1.1 Floating Ball Valve

• Ball Support: The ball is not fixed and can move slightly within the valve body.

• Sealing Mechanism: Line pressure pushes the ball toward the downstream seat, creating a tight single-side seal.

• Seat: The seat is fixed and does not require additional support components.

• Simplicity: Ideal for compact, low-pressure systems due to fewer internal components.

1.2 Trunnion-Mounted Ball Valve

• Ball Support: The ball is supported by upper and lower trunnions (shafts) connected to bearings, keeping it stationary.

• Sealing Mechanism: Spring-loaded or pressure-energized seats press against the ball, creating a dual-side seal.

• Complexity: Requires additional components like bearings and movable seats, making the structure more robust.

2. Operating Principle

Floating Ball Valve

• Pressure from the upstream side pushes the ball against the downstream seat for sealing.

• As the ball moves slightly during opening/closing, there is continuous contact with the seat—leading to higher wear over time.

Trunnion Ball Valve

• Sealing is achieved by the movement of the seats, not the ball.

• Reduced friction during operation results in longer valve life and smoother actuation.

3. Suitable Applications

Floating Ball Valve

• Pressure Rating: Best suited for low to medium pressure (≤ Class 600).

• Valve Size: Typically used in small to medium sizes (≤ NPS 8).

• Media: Clean fluids like water, air, or natural gas without abrasive particles.

Trunnion-Mounted Ball Valve

• Pressure Rating: Handles high-pressure conditions (up to Class 2500).

• Valve Size: Ideal for large-diameter pipelines (up to NPS 60).

• Media: Capable of handling abrasive, viscous, or dirty fluids due to improved seat durability.

4. Operating Torque & Maintenance

Floating Ball Valve

• Torque: Higher torque required in high-pressure or large-diameter applications.

• Maintenance: Simpler design allows easy maintenance, but seat wear is more frequent.

Trunnion Ball Valve

• Torque: Lower operational torque due to stationary ball and dynamic seats.

• Maintenance: Extended maintenance intervals; seats often come with self-compensation or adjustment features.

5. Sealing Performance

Floating Ball Valve

• Type: Single-direction sealing only.

• Limitation: May leak under very low-pressure conditions due to lack of sealing force.

Trunnion-Mounted Ball Valve

• Type: Dual-direction sealing.

• Advantage: Higher reliability and tight shut-off under all pressure conditions.

6. Typical Use Cases

• Floating Ball Valves are commonly used in general industrial systems, building services, and utility pipelines for water, steam, or clean gases.

• Trunnion Ball Valves are widely applied in oil & gas, refineries, power plants, and long-distance transmission pipelines where high pressure and large diameters are involved.

7. Conclusion: Which Valve Should You Choose?

Both floating and trunnion-mounted ball valves offer reliable performance—but they serve different needs.

Parameter	Floating Ball Valve	Trunnion Ball Valve
Pressure Range	Low to Medium	Medium to High
Bore Size	Small to Medium	Medium to Extra-Large
Sealing	Single-direction	Dual-direction
Torque	Higher	Lower
Cost	Lower	Higher
Maintenance	Frequent seat replacement	Longer lifespan, costlier

Need High-Performance Ball Valves?

As a professional valve manufacturer with over 20 years of experience, we specialize in both floating and trunnion-mounted ball valves designed for demanding industries. Our valves are:

• Certified (ISO, CE, API)

• Available in full range: Class 150 – Class 2500, DN15 – DN1500

• Customizable for various media and temperature conditions

Contact us today to get technical consultation, 3D CAD models, and a tailored quotation for your next project.

Optimize your flow. Trust our valves.