What is a ball valve used for?

How the ball valve works

A ball valve is a globe valve that allows, blocks, and controls the flow of liquids, gases, and vapors in a piping system by rotating a ball with a hole in the valve. The ball is mounted on two seats and has a shaft that connects the ball to the operating and control mechanism that rotates the ball. When the cross section of the orifice is perpendicular to the flow area, fluid is not allowed to pass through the valve. Fluid flows through the valve, and the fluid flow rate depends on the area of the hole exposed in the floor.

Ball valve is a kind of quarter-turn valve together with plug valve and butterfly valve. They can be operated manually or using actuators. The simplest operation of a ball valve is with a wrench or a lever turned manually by the operator. Apply torque to turn the lever arm 90° clockwise or counterclockwise to open or close the valve. If the lever arm is parallel to the pipe, the valve is open. If the lever arm is perpendicular to the pipe, the valve is closed.

Ball valve structure

The basic components of a ball valve include:

Ball

A ball is a sphere with a hole in its center. The hole in its center is called a hole. When the fluid flow path and the cross-section of the hole are coplanar, the hole acts as a flow opening for the fluid. Otherwise, traffic will be limited. Ball valves can have solid or hollow balls. A solid sphere has a constant opening diameter throughout its structure, which helps fluid flow smoothly at a constant velocity. Hollow spheres, on the other hand, have a hollow interior with space inside to allow more fluid to pass through the valve. However, larger spaces create turbulence and high speeds. Hollow spheres are lighter and less expensive than solid spheres.

valve body

All internal components of a ball valve are contained within the valve housing or body. It is made of hard metal, thermoplastic or thermoplastic lined metal that protects the ball valve assembly. It also allows access to the external control mechanism that spins the ball.

Axis

The shaft connects the ball to a control mechanism that rotates the ball. There are seals such as O-rings and packing rings on the shaft to seal the shaft and valve cover to avoid fluid leakage. Axles can be operated manually by levers or handwheels, or by electric, pneumatic or hydraulic drives.

Bonnet

The bonnet is an extension of the valve housing that contains and protects the shaft and its packing. It can be welded or bolted to the body. It is also made of hard metal and it covers the opening formed to connect the shaft to the external control mechanism.

Seat

The seat provides a seal between the ball and the valve body. The upstream seat is near the inlet side of the valve. The downstream seat is on the opposite side of the upstream seat, near the discharge side of the valve.

In order to maintain the functionality of the ball valve, the user must keep in mind several limitations:

A ball valve can do throttling, but it should last a long time. When the ball valve is in the throttling position, the valve seat is exposed to high velocity fluid flow and greater compressive forces, which can lead to corrosion. Therefore, it is not recommended for throttling applications. Standard ball valves can be used to throttle low pressure gas. Segmented ball valves can be used in limited throttling applications. However, advanced ball valves with improved designs or seats made from engineered materials suitable for throttling applications are already on the market.

Application is limited by the maximum allowable operating temperature of the seat. For higher temperatures, metal or ceramic seats are an alternative.

Ball valves are available in a variety of designs and functions to meet various industrial needs. Ball valve standards and specifications vary depending on the industry in which it is used.