GET GATE VALVE WIKI INFORMATION

What is a 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. Gate valves require very little space along the pipe axis and hardly restrict the flow of fluid when the gate is fully opened. The gate faces can be parallel but are most commonly wedge-shaped (in order to be able to apply pressure on the sealing surface).

How does a Gate Valve work?

A gate valve is a control valve that either allows media to flow through unobstructed or stops the fluid flow. The main advantage of a gate valve is the straight-through unobstructed passageway, which induces minimal pressure loss over the valve. The unobstructed bore of a gate valve also allows for a pig’s passage in cleaning pipe procedures, unlike butterfly valves. However, gate valves are slower than quarter-turn valves and should only be used in the fully open or closed position, not to regulate the flow. Automated gate valves exist with either an electric or pneumatic actuator, but a manual gate valve is cost-effective since gate valves are typically used infrequently. Gate valves are also commonly referred to as sluice gate valves.

Where are Gate Valves Used?

Gate valves are often used when minimum pressure loss and a free bore are needed. When fully open, a typical gate valve has no obstruction in the flow path resulting in a very low-pressure loss, and this design makes it possible to use a pipe-cleaning pig. A gate valve is a multiturn valve meaning that the operation of the valve is done by means of a threaded stem. As the valve has to turn multiple times to go from the open to the closed position, the slow operation also prevents water hammer effects.

Advantages of Gate Valves

• The gate valve is very simple in design, relatively cheap, and easy to maintain.
• There is almost no pressure drop across the valve when the valve is in the fully open position.
• Replacement of the gate valve disc is usually not a difficult task.
• Replacement of the seat rings is usually not a difficult task.

Disadvantages of Gate Valves

• Gate valves are not well suited to throttling (any valve position between fully open and fully closed) as this creates turbulent flow and frictional losses. A valve left in the almost closed position will cause the flowing medium to flow at a very high velocity across the valve’s seating surfaces, this can lead to damage to the surfaces (‘wire-drawing) and passing/leaking of the valve.
• Gate valves create turbulent flow when throttled and experience excessive vibration as a result. This situation should be avoided to prevent damage from occurring to the valve packing and other internal parts.
• Compared to a globe valve, a gate valve’s seating surfaces are more difficult to refurbish (if seat rings are not used)