Ball Valves: Different Types And Their Applications

If you’re an oil or gas engineer, you know that ball valves are essential components of piping systems. They can be used for various purposes throughout the oil and gas industry to isolate the flow within piping systems.

Oliver Twinsafe’s established range of Double Block and Bleed (DBB) large bore pipeline ball valves will increase operator safety with true double isolation. As well as saving space and weight, reducing potential leak paths and minimising maintenance requirements on both new and existing pipelines. But first, what exactly is a pipeline ball valve?

What is a Ball Valve?

Ball valves are mechanical devices capable of isolating the flow of different substances in either gas or liquid form.

There are different ball valve types with various designs for specific uses, but the basic ball valve parts are commonly the same among the other designs.

Floating Ball Valve

In a floating ball valve, the ball is held in place by two elastomeric seats; between these seats, the ball is able to “float” inside the valve’s body. The valve stem is connected to a slot at the top of the ball; this allows the ball to rotate one-quarter turn or 90 degrees.

The valve shaft allows for a limited amount of lateral movement for the ball generated from upstream pressure against the ball.

This slight lateral movement drops a load upon the ball great enough to press the ball against the downstream seat, improving tightness to avoid leaks.

A large floating ball valve (e.g.above 3”) is hard to operate when the upstream pressure is very high; to combat this problem, a Trunnion mounted ball valve is used instead.

Trunnion Ball Valve

A Trunnion ball valve offers a solution to the problem created by excessive pressure placed on a floating ball valve. Trunnion mounted ball valves have a similar structure as traditional ball valves. The only difference is that trunnion ball valves have additional mechanical anchoring that supports the ball. In the Oliver design we support the ball from both ends on the vertical axis so that the ball stays firmly in place, limiting the wear of the seats at high pressure. The mounted Trunnion ball valve design requires a lower operating torque. This reduces the size of the actuator, as well as the valve’s overall cost. This price difference is an important factor as valve size and pressure class increase.

Traditional VS. Compact Ball Valves

Traditional ball valves are assembled in a three-piece design; the three sections consist of a middle section, which houses the ball and trunnions and two end closures that include seat assemblies and are bolted to the valve body. After these three components are bolted together, they are then bolted into the pipeline. The overall weight of the assembly will add to the weight of the companion weld neck flanges needed to place this valve in line.

The advantage of the compact design comes in applications where space and weight are limited, such as offshore platforms. Compact valves house all components in a small, robust body design. The internals are held in place by a threaded retainer that is tightened into the body. Compact designs are significantly smaller and lighter when compared to the space and weight required for bolting a three-piece valve assembly that needs companion flanges. Specific to the Oliver design we are able to produce the compact design complete with two balls in a B16.10 face to face dimension.

We are specialists when it comes to the design and manufacturing of Trunnion Ball Valves.

If you would like more information, please contact Oliver Twinsafe today!