Gate Valve

A gate valve, also known as a sluice valve, is a valve that opens by lifting a barrier (gate) out of the path of the fluid.

A gate valve is the most common valve for water supply systems. It represents a linear-motion isolation valve and has a function to stop or allow the flow. Gate valves got their name from the closure element sliding into the flow stream to provide shutoff and, therefore, acting like a gate.

What is a gate valve used for?

A gate valve is the most common valve for water supply systems. It represents a linear-motion isolation valve and has a function to stop or allow the flow. Gate valves got their name from the closure element sliding into the flow stream to provide shutoff and, therefore, acting like a gate. Gate valves are used to isolate specific areas of the water supply network during maintenance, repair works, new installations, as well as to reroute water flow throughout the pipeline.

Design & parts of a gate valve

A gate valve has a simple design and can be applied in many low pressure-drop services, which makes it one of the most common valves in use today. Gate valves are designed as full-port valves. This means that the valve port is of the same size as the inner diameter of the connecting pipe. Full-bore gate valve passes the fluid flow without any obstructions to a flow and do not cause a pressure drop in a pipeline. This also allows to clean the pipe using a cleaning pig.

A resilient seated gate valve with a non-rising spindle consists of the following parts:

• wedge

• ductile iron valve body

• seating area

• stem (spindle)

• spindle bearing

• bonnet

• packing.

The body is the largest element of the gate valve. Since the spindle remains in the valve body during rotation, it allows an economical bonnet construction. The valve bonnet itself is joined to the body with bolts, which allows cleaning and maintenance. As the gate valve closes, the wedge travels down until it presses the valve seat, which would mean a complete shutoff. During the opening the wedge slides towards the upper part of the valve body.

A wedge gate valve construction did not alter a lot for the last 100 years. However, the design of some elements of the gate valve has undergone some modifications. Most of the changes are aimed at increasing the service life of the gate valve, improving the sealing characteristics, using superior quality materials and epoxy coatings for a better corrosion protection. At the same time, the modern gate valve body has a compact sleek design, allowing installations in limited space conditions.

Parallel vs wedge-shaped gate valves

Gate valves can be divided into two main types: Parallel and wedge-shaped. The parallel gate valves use a flat gate between two parallel seats, and a popular type is the knife gate valve designed with a sharp edge on the bottom of the gate. The wedge-shaped gate valves use two inclined seats and a slightly mismatched inclined gate.

How does a gate valve work?

Gate valves are designed to turn the flow of a liquid on or off by restricting or opening the flow with a round or rectangular wedge. Gate Valves can also control the pressure of liquid flow through pipes or valves.

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