If you are an oil or gas engineer, you know that ball valves are a very important component of a pipeline system. They are used for a variety of purposes throughout the oil and gas industry. For upstream applications, they control the flow of oil. For midstream, they protect equipment by controlling the flow of natural gas and oil. For downstream, they are used to refine crude oil.

Because of their popularity in the industry, it is important that every engineer be familiar with the various valves or at least the most common ones.

Ball Valve Applications and Benefits

Ball valves can be used for different types of fluid service, such as on/off shutoff valves with gas-tight shutoff.

In addition to hydrocarbon systems, they are also suitable for air, gas and steam systems.

They are useful for connecting instruments through instrument tubing.

Metal-sealed ball valves are available for high temperature and high pressure applications.

Ball valves are easy to operate and cost effective.

A variety of types and configurations make it easy to find the right ball valve for your requirements.

Ball valves are more compact and lighter than gate valves of the same class and size.

Even at high pressures, ball valves open and close very quickly with a gas-tight seal.

1. Three-way ball valve

Depending on the situation, the ports of a three-way ball valve can be set up in one of three ways.

One inlet, two distributions.

One inlet, one outlet, one distribution; or

Straight through (no inlet).

American ball valves are available in three different styles: full ported, reduced ported, and venturi ported.

The full port type has an inside diameter equal to the inside diameter of the pipe. This allows for pipe clearing. In the reduced port and venturi port types, the port is usually a smaller pipe size than the line size.

The ball inside the valve can be free-floating or fixed - referred to as floating and fixed, respectively. Fixed type valves are sometimes referred to as mounted ball valves.

2. Floating ball valve

In a floating ball valve, the ball is held in place by two resilient seats. Between these seats, the ball is able to "float" in the valve body.

The stem is connected to a slot in the top of the ball. This allows the ball to rotate a quarter turn, or 90 degrees.

The spindle allows limited lateral movement of the ball, which is generated by upstream pressure on the ball. This lateral movement is small, but the load on the ball is sufficient to press the ball against the downstream seat. This improves sealing to avoid leakage.

This type of ball valve is capable of closing in both directions. However, when the upstream pressure is very high, the floating ball valve is difficult to operate. To solve this problem, a mounted ball valve is used instead.

3. Mounted Ball Valve

The mounted ball valve provides a solution to the problem created by excessive pressure applied to the floating ball valve.

In mounted American ball valves, a short shaft called a trunnion is set in the valve body. In this design, the ball and steam work together as a single unit. Two floating or spring-loaded seats support the ball.

The mounted ball valve design requires a low operating torque. This, in turn, reduces the size of the actuator and the total cost of the valve. This cost differential is an important factor as valve size and pressure rating increase.

4. Split-Body Ball Valves

In a split-body ball valve, the valve body is divided into two halves or thirds. The ball, stem, seat ring, and other internal mechanisms are bolted to the inside of the valve body.