Ball Valves: How Do They Work?
08 Feb,2022

A port, also known as a bore, is situated in the center of the ball. If this central port is positioned up in the same direction as the attached pipeline, the ball valve is in the open position, allowing fluid or gas to flow through. When the port becomes perpendicular to the flow direction, the ball valve closes, blocking the flow path and stopping any liquids from passing through.

Although most standard ball valves have special stop measures that only allow for a 90-degree rotation, a few allow for complete 360-degree rotation. While a 90-degree rotation is theoretically all that is needed for ball valves to open and close, there are some applications where the complete movement of the core is preferable. Because of its effective and air-tight sealing when closed, the ball valve is a common industrial option. This makes them especially well suited to industries transporting dangerous chemicals or gases, such as natural gas, which require a safe and fast shutoff. However, they should not be used in throttling-like applications where the seats’ integrity can be jeopardized by constant wear.

The movement of the ball characterizes three different types of ball valves:

1. Trunnion Mounted Ball Valve – This form of ball valve has an additional mechanical anchoring mechanism at the top and bottom, making it more suitable for use in high-pressure applications. Since the comprised trunnion-mounted stem absorbs any additional thrust or pressure from the pipeline, it prevents unnecessary stress from affecting operations and shortening working life.

2. Floating Ball Valve – It lacks the trunnion’s extra steading component and is instead only attached to the stem. These ball valves get their name because the ball floats downstream of the stream, pressing in contradiction of the seat to create its seal.

3. Rising Ball Valve – This type of ball valve uses a tilt-and-turn mechanism to minimize seal rubbing, one of the most common causes of premature valve failure. The core wedges against the valve’s seating for complete shutoff when the valve is turned to the closed position. The center core tilts away from the seal when the valve is turned to the open position, allowing the liquid or gas flow to move evenly through.

What Are the Benefits of Using a Ball Valve?

Ball valves are a commonly used system in a variety of industries. Their straightforward but dependable nature makes them a popular option for residential applications. However, their cost-effective manufacturing process and simple maintenance make them ideal for commercial use.

But, before you go ahead and mount these valves in your structure, you might want to learn more about how they function. Here’s a rundown of these valves’ functions and basic structure to help you gather this knowledge.

Ball valves are extremely common because of their lightweight and low-maintenance nature, which does not require lubrication while still providing a close-fitting seal with minimal torque. When choosing between all of the valve arrangement styles, ball valves are as well as least expensive choice.

The most important drawback of ball valves is that most designs have poor throttling characteristics, easily eroding the valve seat. The trunnion has somewhat mitigated this mounted ball valve design, but it should still be a factor for those considering ball valves for applications requiring high throttling.

Ball valves are also common because of their ability to work well in various applications and markets. Ball valves are common in the oil and gas industry, but they’re also used in many other industries, including manufacturing, chemical storage, and even residential applications.

How does a ball valve work?

The ball valve’s working mechanism operates in this manner in general. If the valve is opened manually or by an actuator, some force is needed to turn the lever or handle a quarter turn. The force is moved to the stem, which opens the disc.

The hollowed side of the ball disc faces the media flow as it rotates. The lever is perpendicular to the flow of media at this point, and the port is parallel to the flow of media. Only a quarter-turn is allowed due to a handle stop near the stem and bonnet link.

The lever is turned back a quarter turn to shut the valve. The stem rotates the ball disc in the opposite direction, preventing media flow. The lever is parallel to the port, which is perpendicular.

Take notice, however, that there are three different types of ball disc movement. Each of these has its own set of functions.

The ball disc of the floating ball valve is suspended from the stem. The ball disc partly trusts on the internal force for the close-fitting seal ball valves are known since there is no protection at the lower part of the ball.

As the valve closes, the ball is pushed towards the cupped downstream seat by the media’s upstream linear pressure. This increases the valve’s sealing factor by providing positive valve tightness. When the valve is closed, the internal pressure is carried by the floating ball valve design’s downstream seat.

The trunnion mounted ball valve is another form of ball disc design. The ball disc is held steady by a series of trunnions at the bottom of the disc. When the valve closes, these trunnions absorb the force from the pressure load, reducing friction between the ball disc and the seat. Both upstream and downstream ports are subjected to sealing strain.

When the valve closes, spring-loaded seats push against the disc, which rotates only in one direction. These springs firmly grip the seat to the ball. Balls mounted on trunnions are ideal for applications where high pressure is not needed to transfer the ball to the downstream seat.

Finally, the tilt-and-turn mechanism is used by the expanding stem ball valve. When the valve closes, the ball disc wedges into the seat. When it opens, the disc tilts away from the seat, allowing media to circulate freely the flow of liquid.

Final thoughts

Understanding how a ball valve operates allows you to make informed decisions about whether or not these valves are right for you.