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What are the types of industrial valves--Gate Valve

author: ATHENA GROUP

2023-05-24

What is the valve? Valve is one type of the pipeline accessories, which is used to open and close lines, control flow direction, adjust and control the parameters of conveying medium (temperature, pressure and flow). Valve is the control component in the fluid conveying system, with the functions of cut-off, regulation, diversion, preventing countercurrent, pressure stabilization, diversion or overflow pressure relief. Valves can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metal and radioactive media. Then what is the Industrial Valve? Industrial valve is one type of mechanical device that open, close or partially obstruct passageways to regulate the flow of liquid or gas within a system.

While they all provide similar functions, industrial valves have evolved into various types with specialized designs and features to meet a number of application-specific requirements. The main types of industry valves including:

•   Gate Valves
•   Globe Valves
•   Ball Valves
•   Butterfly Valves
•   Check Valves

Below we just talk about Gate Valve only.

Gate valve (gate valve) is a opening and closing gate, the movement direction of the gate is perpendicular to the fluid direction, the gate valve can only be fully opened and closed, cannot be adjusted and throttling. Gate valve is sealed through the contact between the valve seat and the gate disc. Usually, the sealing surface will over-layed with metal materials to increase the wear resistance. Regarding to the wedge, there have flexible wedge and solid wedge, according to the different wedge, gate valve is divided into flexible wedge gate valve and solid wedge gate valve. This type of valves are generally with different materials such as carbon steel, stainless steel, cast iron, alloy steel, duplex steel and etc.

Working Principle

The closure of the gate valve is the wedge/disc. There are two types of wedge/disc: solid wedge and flexible wedge. The movement direction of the wedge/disc is perpendicular to the fluid direction. The gate valve can only be fully opened and closed, and cannot be adjusted and throttling. The wedge is with two sealing surfaces, the most commonly used type is the two sealing surfaces of the disc will be in wedge type, wedge angles vary with the valve parameters, usually is 5°. When the medium temperature is not high, the angle will be around 2°52 '. The disc of the wedge gate valve can be with integral type called solid wedge. To improve the process of the sealing surface, the wedge also can be with flexible one. This type of disc is called flexible wedge. When the gate valve is closed, the sealing surface can be sealed only by the medium pressure, that is, relying on the medium pressure to press the sealing surface of the gate to the valve seat on the other side to ensure the sealing of the sealing surface, which is self-sealing. Most of the gate valve is forced sealing, that is, when the valve is closed, to rely on external force to force the gate pressure to the valve seat, to ensure the sealing of the sealing surface. If the disc is with the valve stem together for linear movement, which is called rising stem gate valve. For the gate valve, if the stem nut is located on the wedge/disc, the hand wheel rotation to drive the valve stem rotation to make the disc/wedge lifting, this type of valve is called the non-rising stem gate valve.

Advantages
• For gate valves the flow resistance is very small. Due to the internal medium channel of the valve body is straight through, and the medium flows into a straight line, so the flow resistance is small.

• When opening and closing, it is save labour, which is compared with the globe valve. Because no matter it is open or closed, the disc movement direction is perpendicular to the direction of the medium flow.
• Gate Valve is with high height and long opening and closing time. The opening and closing stroke of the gate is large, and the lifting/rising is carried out through the screw.
• The water hammer phenomenon is not easy to bring due to gate valve with the long closing time.
• The medium can flow to either side in both directions and is easy to install. The gate valve channels are symmetrical on both sides.

•The face to face dimension (the distance between the two connecting ends of the shell) is small.

•With simple structure, good manufacturing technology and a wide range of application.

•Gate valve is with good inflexibility, smooth channel, long service life, reliable sealing, light and flexible operation.

Disadvantages
• Compared with Globe Valve, the machining and manufacturing of gate valve is much more complex. This is due to Gate Valve is with two sealing facing.
• For gate valve, there is relative friction between the sealing surface. The wear is larger, and the sealing surface is not convenient to repair after the wear.
• The valve cavity structure size is large, resulting in large external size, large installation space.
• Valve opening and closing time is long.

• Gate Valve is easy to form a closed valve cavity.

Applications:
• Gate valves are suitable to use in high temperature and pressure conditions.
• They are used for on-off applications

• 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.

• Gate valves can be used for underground water or sewage disposal applications. They are also commonly found in irrigation and distribution service lines. Gate valves are suited for low-pressure steam, and non-corrosive gas or oil.

• Gate valves are also common in applications using liquids like heavy oils, light grease, varnish and other non-flammable liquids.

• Gate valves are best suited for applications that require infrequent operation and small installation space.

• Gate valves are used for various purposes and they can be seen commonly in homes and commercial centers.