A gate valve is a common type of valve used to prevent or allow fluid flow inside pipeline systems in process plants. It has a gate or wedge style disc that will move perpendicular to stop or start the fluid flow. These valves will either be in a fully open or fully closed state.
The operating mechanism is straightforward. The handle wheel connected to the body of the valve is used for operating the valve. To rotate the stem, you need to turn the handle. The gate moves upwards or downwards based on the rotation. They require multiple turns of 360 degrees to open or close the valves fully. When you lift the gate from the path, the valve opens, allowing the free flow of fluids. As you bring down the valve, it fully closes the valve and seals the path completely. The rubber surface on the seat and the gate help achieve a proper and tight seal.
However, as the top gate valve manufacturer in India, we insist that gate valves must not be used for throttling or regulating flow as accurate control cannot be achieved. A high-velocity flow in a semi-open/close state will erode the seating surface and the disk, creating noise and vibration.
Gate valves have three main components, namely, bonnet, body and trim. The bonnet comprises moving parts and is connected to the body using bolts, screws, welding or pressure seal. The valve trim comprises the gate, either wedge or disc, stem, and seat rings. You need to flange, screw or connect the body to the piping system to install the valve. Gate valves are classified based on the different design of the disk, bonnet joint and stem movement.
The classification of gate valves based on disk type includes -
Parallel Gate Valve
Parallel gate valves use a parallel faced flat gate with a single or twin disc and a spreading mechanism. The fluid pressure gives the required force to control the valve seat. As the disc slides across the seat, these valves are used in applications that handle fluids. Parallel gate valves are of three types, namely,
Solid Taper Wedge Valve
A solid taper or plain wedge is a widely used disc type as it has strength and simplicity. It is either hollow or solid in construction and can be installed in any position. This type of valves is used in all fluid applications that have turbulent flow. It is not suitable for high-temperature application as it causes thermal locking where the wedge gets stuck between the seat due to the expansion of metals.
Split Wedge Valve
A split wedge valve has two solid disks held together by a spring or spacer ring. To keep the discs together, the body moves along with the assembly. It is the most self-aligning and self-adjusting type of disc. This flexibility enables the wedge to seal easily and reduce sticky surfaces. It is mostly used in applications that require liquid, corrosive liquid and non-condensing gases at a normal temperature.
Flexible Wedge Valve
A flexible wedge is a simple wedge with a single piece solid disk with either a cut on the perimeter or an integral boss in the middle. It is flexible enough to find its orientation.
The Bonnet joint is a mechanism that holds the body and the bonnet together. The different joint mechanism in gate valves are -
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