Do You Know Why High-pressure Trunnion-mounted Ball Valves Are Only Used in Fully Open Or Fully Closed Positions?

Why high-pressure trunnion-mounted ball valves are only used in fully open or fully closed positions?

The high-pressure trunnion-mounted ball valve consists of a left valve body, right valve body, middle valve body, ball, upper stem, lower stem, sealing components, and mounting parts. Its main feature is the fixed connection between the upper stem and the ball using a bottom-installed structure. The lower end of the upper stem is shaped into a hexagonal valve shaft, which connects to a hexagonal hole on the ball. This design provides blowout protection for the upper stem and reduces extrusion stress during opening and closing, making it suitable for high-pressure, large-diameter pipelines.

The working principle of the ball valve relies on the rotation of the ball around its central axis to open or close the valve. The valve stem drives the ball to rotate clockwise, and when the ball's hole aligns with the pipeline, the valve is open. Conversely, when the ball is perpendicular to the pipeline, the valve is closed. The ball, as the shut-off component, primarily serves to cut off or change the flow direction of the medium in the pipeline. However, since the ball valve's edges are susceptible to erosion and damage during throttling, ball valves are designed for full open or full close positions only.

Advantages of High-Pressure Trunnion-Mounted Ball Valves:

1. Low Fluid Resistance: Ball valves have relatively low fluid resistance compared to other valves. Even reduced bore ball valves have minimal resistance.

2. Quick and Easy Operation: With just a 90° rotation of the valve stem, the ball valve can be fully opened or closed, allowing for fast and convenient operation.

3. Excellent Sealing Performance: The valve seat seal ring is usually made of elastic materials such as PTFE, ensuring good sealing performance. The sealing force increases as the medium pressure increases.

4. Reliable Stem Sealing: During operation, the valve stem only rotates, which reduces the likelihood of damage to the stem packing. The reverse sealing force on the stem increases with medium pressure, improving sealing reliability.

5. Ease of Automation and Remote Control: Since the ball valve only requires a 90° turn for operation, it is easy to automate and control remotely. It can be equipped with pneumatic, electric, hydraulic, pneumatic-hydraulic, or electro-hydraulic actuators.

6. Smooth Channel: The valve's passage is smooth and free from obstructions, making it less likely for medium to accumulate, allowing for easy pigging (cleaning of pipelines).

   
   

Operation and Maintenance Notes:

Before operating a ball valve, always check the valve's open/close indicator. For valves that have not been operated for an extended period (over 6 months) or after cleaning/lubrication, it is recommended to inject a small amount of cleaning fluid and sealant before operation to protect the valve's sealing surfaces.

Before operating, check the valve's status. If fully closed, inspect the pressure at both ends of the valve. For ball valves with bypass circuits, if the pressure difference between the two ends exceeds 1 Mpa, open the pressure balance valve to equalize the pressure on both sides. When the upstream and downstream pressure difference is less than 1 Mpa, the valve can be operated. It is important to note that ball valves should only operate in fully open or fully closed positions and are not designed for throttling or partial flow control.

Forged Steel Trunnion Mounted Ball Valve are robust and reliable components used for managing the flow of fluids in high-pressure and high-volume applications. Unlike floating ball valves, their design includes a stationary ball supported by trunnions, which reduces stress on the seats and ensures precise operation. This makes them a preferred choice in industries such as oil and gas, petrochemicals, and power generation.

One of the standout features of Fixed trunnion-mounted ball valves is their ability to handle extreme pressures without compromising sealing integrity. The fixed ball design minimizes torque requirements, making them easier to operate, especially in larger sizes. Additionally, these valves provide bi-directional sealing, ensuring leak-free performance even under demanding conditions.Engineered for durability, trunnion-mounted ball valves are constructed from premium materials such as stainless steel and carbon steel to withstand harsh environments and corrosive media. Their robust design not only extends their operational lifespan but also reduces maintenance needs, enhancing cost-efficiency and reliability in critical systems.With advancements in technology, modern trunnion-mounted ball valves come equipped with features such as double block-and-bleed capabilities, fire-safe designs, and anti-static mechanisms. These enhancements improve safety, efficiency, and adaptability, making them indispensable in applications requiring superior flow control and reliability.