High Pressure Gate Valve Types and Working Principle

How does a high-pressure gate valve work? 

A high-pressure gate valve operates manually or through automation. The basic working principle remains the same whether the valve is manual or automated: the actuator rotates the stem to start/stop flow. The valve starts when the actuator rotates clockwise for several turns. As such, the stem converts the rotary motion to linear movement. This linear motion causes the valve disc to move upwards, leaving the valve open. With the valve open, fluid starts flowing through the valve. The valve stops flow when the actuator is rotated counterclockwise, forcing the stem and disc to move downwards. As such, the disc seals the valve’s central hole where liquid flows through. At this state, the valve is closed, and there is zero fluid flow.

Figure: Working of a high-pressure gate valve.

Types of high-pressure gate valves 

Through-conduit high-pressure gate valve 

This type of valve is made as one unit with a bore-sized hole on the disc. When the valve is started, the disc moves upwards, allowing the bore to be aligned concentrically with the pipe connected to the valve. This design leads to a smooth fluid flow free from turbulence and, thus, a low-pressure drop. With the low-pressure loss, this valve is suitable for long-distance transportation of fluids like natural gas and crude oil. The design of this valve allows the seats to remain clean. However, a cavity on the valve disc tends to retain solids. The cavity is designed with a built-in plug to help drain the accumulated solids. This valve is suitable for use in the piping system where pigs clean debris or deposits accumulation.

Figure: Through-conduit high-pressure gate valve

High-pressure wedge gate valve

This is the type of valve in which the disc is designed with a wedge shape instead of having a parallel surface. Developing the valve with a wedge shape aims to enhance supplementary seating load to enable the disc seal against high pressure effectively. Due to this design, the valve has a higher degree of achieving seat tightness and thus ensures zero leakage when the valve stops.

Figure: High-pressure wedge gate valve.

Manually actuated high-pressure gate valve

This is the type of valve that is operated manually. One of the main advantages of this valve is its low cost compared to others that are automated. Also, operating the valve manually reduces the inconveniences caused by a power outage in automated valves. As such, where there is power or there isn’t, the valve will still function. Also, in case of an emergency, the operator will be able to stop the valve immediately. However, this valve poses some risks to the operator. For example, where the fluid being conveyed is hazardous, any slight leakage may cause a severe health hazard to the operator. Also, the high pressure fluid remains dangerous to operator in case of any slight leakage.

Electrically actuated high-pressure gate valves 

Electrically actuated high-pressure gate valves operate by using an electric actuator. The electric actuator provides the torque to open or close the valve disc. It works by converting electrical energy into mechanical energy. The mechanical energy is responsible for turning the valve stem to create linear motion on the disc to start or stop the fluid flow as necessary. This valve helps to automate industrial systems, which leads to improved efficiency. These valves are also advantageous in relieves you the cost of having a valve operator. It also reduces costs associated with manual valves, such as injury to the operator. Also, electrically actuated high-pressure gate valves are very clean, which makes them suitable where hygiene is demanded. However, in case of power outage, the valve will not operate.

Figure: Electrically actuated high-pressure gate valve.

Pneumatically actuated high-pressure gate valves 

This is a high-pressure valve that is operated by using a pneumatic actuator. The actuator operates by using compressed air. The compressed air acts on the piston in the actuator, causing rotary motion. The rotary motion is transmitted to the stem. The stem rotates, causing the valve disc to open or close the valve. Using air as the operating fluid makes the valve free from contamination.