Trunnion Ball Valve

What is the Function of Trunnion?

The trunnions in a trunnion ball valve are a key support structure for the ball, ensuring stability, durability, and efficient operation under high-pressure conditions. Unlike conventional ball valves, where the ball is supported only by the seat, trunnion ball valves include fixed shaft-like supports (called trunnions) at both the top and bottom of the ball.

These trunnions have several key functions:

1. Stability and support

The trunnions hold the ball securely in place, preventing unwanted movement during operation.

This stability ensures that the ball rotates smoothly within the valve body, even under high flow or pressure conditions.

2. Reduce seat stress

The trunnions absorb excess pressure from the pipeline media, reducing the load on the valve seat.

This minimizes wear on the sealing components and extends the service life of the valve.

3. Reduce torque

By supporting the ball, the trunnions reduce friction between the ball and the seat.

The reduction in resistance reduces operating torque, making the valve easier to operate manually or using an actuator.

4. Enhanced Sealing Performance

The trunnion maintains precise alignment of the ball and seat, ensuring a consistent and reliable seal.

This is especially important for high-pressure or double block and bleed applications.

5. Accommodates Large, High-Pressure Applications

Due to the added support, the trunnion-mounted ball valve is suitable for large-diameter pipes and high-pressure systems.

What is the Purpose of a Trunnion in a Ball Valve?

The trunnions in ball valves play a vital role in providing stability, reducing wear and increasing valve efficiency, especially in high-pressure and large-scale applications.

The trunnions in ball valves provide structural support by securing the ball at the top and bottom, ensuring stability, reducing wear and precise alignment under high pressures.

This design minimizes stress on internal components, extending service life and allowing trunnion-mounted valves to handle larger diameters and higher pressures with lower torque.

When to Use a Trunnion Ball Valve?

Electric actuated trunnion ball valves should be used when stability, high pressure resistance, low torque, and long-lasting performance are required, especially in large, high temperature, or high-risk industrial systems.

High-Pressure Applications

Electric actuated trunnion ball valves are ideal for high-pressure applications because the trunnion brackets firmly support the ball at the top and bottom, preventing the ball from moving under pressure. This ensures reliable operation in high-pressure systems.

Large Diameter Pipes

Trunnion ball valves are the preferred choice for large systems with larger pipe diameters. The trunnion design helps handle increased flow and pressure without excessive torque, making them suitable for larger pipe operations.

High-Temperature Environments

Electric actuated trunnion ball valves are ideal for high-temperature environments where maintaining a secure seal and proper function is critical. Their rugged construction and trunnion supports allow them to withstand thermal stresses and maintain performance in extreme temperatures.

Frequent On/Off Cycles

Trunnion ball valves are effective when frequent on/off operations are required. The quarter-turn mechanism provides quick, reliable flow control, making them ideal for applications that require the valve to be opened or closed quickly.

Heavy-Duty or Critical Applications

In industries such as oil and gas, petrochemical, power generation, and chemical manufacturing, where reliable and consistent performance is critical, trunnion ball valves are essential. Their ability to provide a tight seal, minimal leakage, and long service life makes them ideal for these heavy-duty and high-risk applications.

Low Operating Torque Requirements

Electric actuated trunnion ball valves are a good choice if the application requires low operating torque. Their design reduces friction between the ball and seat, which means less force is required to open or close the valve, which is especially beneficial in automated systems.

Harsh Service Conditions

Trunnion ball valves are very effective in harsh service conditions, such as systems handling abrasive or corrosive materials. Their durable construction and reliable sealing ensure that the valve will perform well even in challenging media conditions.

Are trunnion ball valves dbb?

Electric actuated trunnion ball valves can be designed as double block and bleed (DBB), but not all trunnion ball valves have DBB function. It depends on the design and application scenario of the valve. Two common seat sealing structures of fixed ball valves.

1. DBB double block and bleed valve: A valve with two seat sealing pairs. In its closed position, it can provide pressure sealing at both ends of the valve by discharging/exhausting the valve body cavity between the two seat surfaces.

2. DIB double isolation and bleed valve: A valve with two seat sealing pairs. Each seat sealing pair can provide a single-source pressure seal in the closed position by discharging/exhausting the valve body cavity between the two seat sealing pairs.

Does the trunnion ball valve have DBB function?

Trunnion ball valve with DBB function:

Electric actuated trunnion ball valves are often used in high-pressure, large-diameter or special working conditions. Many trunnion ball valves are designed to support double-block and double-bleed functions. They usually have a middle cavity discharge port to release the middle cavity pressure and realize the DBB function.

This type of valve is widely used in industries that require high safety, such as oil, gas and chemicals.

Trunion ball valve without DBB function:

Some electric actuated trunnion ball valves are used in ordinary isolation or flow control scenarios. They may not be equipped with a middle cavity discharge device and therefore do not have the DBB function.

How to determine whether the trunnion ball valve is DBB?

1. Check the product technical parameters or design instructions.

2. Confirm whether it has a middle cavity discharge port and related design.

3. Check whether it meets the definition of DBB function in international standards such as API 6D.