Gate valve is the product of industrial revolution. Although some valve designs, such as globe valves and plug valves, have existed for a long time, gate valves have occupied a dominant position in the industry for decades, and only recently did they cede a large market share to ball valve and butterfly valve designs.

The difference between gate valve and ball valve, plug valve and butterfly valve is that the closing element, called disc, gate or occluder, rises at the bottom of the valve stem or spindle, leaves the waterway and enters the valve top, called bonnet, and rotates through the spindle or spindle in multiple turns. These valves that open in a linear motion are also known as multi turn or linear valves, unlike quarter turn valves, which have a stem that rotates 90 degrees and do not normally rise.

Gate valves are available in dozens of different materials and pressure ratings. They range in size from the NPS that fits your hand ½ Inch to large truck NPS 144 inch. Gate valves consist of castings, forgings, or components fabricated by welding, although the casting design dominates.

One of the most desirable aspects of gate valves is that they can be fully opened with little obstruction or friction in the flow holes. The flow resistance provided by the open gate valve is roughly the same as that of a section of pipe with the same port size. Therefore, gate valves are still strongly considered for blocking or on/off applications. In some valve nomenclature, gate valves are called globe valves.

Gate valves are generally not suitable for regulating flow or operating in any direction other than full open or full close. Using a partially open gate valve to throttle or regulate flow may damage the valve plate or valve seat ring, because in a partially open flow environment that causes turbulence, the valve seat surfaces will collide with each other.

Gate valve style

From the outside, most gate valves look similar. However, there are many different design possibilities. Most gate valves consist of a body and a bonnet, which contains a closing element called a disc or gate. The closing element is connected to the stem passing through the bonnet and finally to the handwheel or other drive to operate the stem. The pressure around the valve stem is controlled by the packing being compressed into the packing area or chamber.

The movement of gate valve plate on the valve stem determines whether the valve stem rises or screws into the valve plate during opening. This reaction also defines the two main stem/disc styles for gate valves: rising stem or non rising stem (NRS). The rising stem is the most popular stem/disc design style in the industrial market, while the non rising stem has long been favored by the waterworks and pipeline industry. Some ship applications that still use gate valves and have small spaces also use the NRS style.

The most common stem/bonnet design on industrial valves is external thread and yoke (OS&Y). The OS&Y design is more suitable for corrosive environments because the threads are located outside the fluid seal area. It differs from other designs in that the handwheel is attached to the bushing at the top of the yoke, not to the stem itself, so that the handwheel does not rise when the valve is open.

Gate valve market segmentation

Although in the past 50 years, right angle rotary valves have occupied a large share in the gate valve market, some industries still rely heavily on them, including the oil and gas industry. Although ball valves have made progress in natural gas pipelines, crude oil or liquid pipelines are still the location of parallel seated gate valves.

In the case of larger sizes, gate valves are still the main choice for most applications in the refining industry. The robustness of the design and the total cost of ownership (including the economy of maintenance) are the desirable points of this traditional design.

In terms of application, many refinery processes use temperatures higher than Teflon’s safe operating temperature, which is the main seat material for floating ball valves. High performance butterfly valves and metal sealed ball valves are beginning to gain more use in refinery applications, although their total cost of ownership is usually higher than that of gate valves.

The water plant industry is still dominated by iron gate valves. Even in buried applications, they are relatively cheap and durable.

The power industry uses alloy gate valves for applications involving very high pressures and very high temperatures. Although some newer Y-type globe valves and metal seated ball valves designed for blocking service have been found in the power plant, gate valves are still favored by plant designers and operators.