The main components of the gate valve structure are the valve body, valve cover, valve stem, gate, valve seat and transmission device. The following is a detailed introduction for you.
1. Valve body
The valve body is the cast iron of the gate valve, which is directly connected to the pipeline and constitutes the pressure-bearing component of the medium flow channel. It is an important part for installing the valve cover, placing the valve seat and connecting the pipeline. The valve body must accommodate the vertical and lifting disc-shaped station, so the height of the inner cavity of the valve body is relatively large.
The structure of the gate valve body determines the connection between the valve body and the pipeline, and the valve body and the valve cover. The valve body blank can be cast, forged, forged and welded, and welded to the tube sheet. Cast valve bodies are generally used for diameters ≥ DN50, forged valve bodies are generally used for diameters ≤ DN50, forged and welded valve bodies are used for valves that are difficult to forge as a whole and are used in important occasions, and cast-welded valves are used for valves that cannot meet the requirements of overall casting, and cast-welded structures can be used.
2. Valve cover
The valve cover is the main pressure-bearing component connected to the valve body and forming a pressure chamber with the valve body, with a stuffing box on it. For medium and small-caliber valves, the valve cover is provided with a mechanism to support parts such as the valve stem nut or transmission device.
3. Valve stem
The valve stem is directly connected to the valve stem nut or transmission device, and the light stem part forms a sealing pair with the packing, which can transmit torque and play the role of opening and closing the gate. According to the thread position on the valve stem, it is divided into a clear stem gate valve and a dark stem gate valve.
4. Gate plate
The gate plate is the opening and closing part of the gate valve. The opening and closing, sealing performance and life of the gate valve mainly depend on the gate plate. It is the key pressure control part of the gate valve. According to the structural form of the gate plate, it can be divided into parallel gate valves and wedge gate valves.
5. Valve seat
The valve seat is a part that fixes the valve seat to the valve body by rolling, welding, threaded connection, etc. to form a sealing pair with the gate plate. The valve seat sealing ring can be directly welded on the valve body to form a sealing surface according to customer requirements. For cast iron, stainless steel, and copper alloy valves, the sealing surface can also be directly processed on the valve body.
6. Transmission device
The transmission device can directly transmit electricity, air and manpower to the valve stem or valve stem nut. In power plants, handwheels, valve covers, transmission mechanisms, connecting shafts and universal couplings are often used for long-distance driving.