The Features and Performance of Butterfly Valve
Jan 18,2023Read More
Butterfly valve is a valve named according to the shape of the opening and closing parts. The opening and closing parts can be round or rectangular. The valve core controls the opening and closing of the valve by rotating clockwise or counterclockwise around the valve stem. The butterfly valve has the advantages of simple structure, light weight, small space required for installation, short stroke and fast opening and closing speed, so it is widely used, especially in petrochemical, water conservancy and electric power industries. There are various types of valves, and butterfly valves are no exception. This time, we mainly choose clip-type butterfly valves and flanged butterfly valves to explain and compare. After reading this article, you will know the butterfly valves of these two connection methods well.
The wafer butterfly valve has no flange on its body, so its body structure length is relatively small, and it mainly depends on the extrusion of the flanges at both ends to achieve the sealing effect. Wafer butterfly valves usually use soft seals (non-metallic seals), which are mainly used in pipes with small diameters or low temperatures. Valves of this type of connection have high accuracy for construction and installation. If the pipe flanges on both sides are misaligned, there is a deviation, then the bolt will be subject to a large shear force when tightening, and the valve may leak; or work under high temperature working conditions, as the temperature rises, the bolt will expand with heat and contract with cold, such factors can also cause leakage in wafer style valves. From the perspective of installation, it is recommended to use less horizontal installation and more vertical installation. Wafer butterfly valves generally cannot be installed at the end of the pipeline and where the downstream needs to be disassembled, because when the downstream flange is removed, the wafer butterfly valve will fall off. In this case, it is necessary to make another pipe joint In order to disassemble, the flanged butterfly valve does not have the above problems, but the cost will be relatively high. Compared with valves of other connection methods, the production cost of clip-on butterfly valves is lower, and the later operation and maintenance are also more convenient. In the case of low production conditions, it is recommended to give priority to purchasing clip-on butterfly valves.
Flanged butterfly valve is the most common valve connection method in the industrial field. Its production method is generally to design a qualified flange butterfly valve model first, then pour molten steel in a molten state into the model, and perform machining and drilling after it cools down. The flange connection direction can be installed vertically or horizontally; it can be installed on high-temperature and high-pressure pipelines, and can also be installed on low-temperature and low-pressure pipelines. At the same time, there is no mandatory requirement for the nominal diameter of the pipeline, and the application range is the widest.
Compared with the wafer butterfly valve, the structural length of the flange butterfly valve is slightly larger, and gaskets of corresponding specifications need to be added during installation. Of course, the sealing types of the flanged butterfly valve connection are more complicated than those of the wafer type. In the face of high pressure conditions, the flanged butterfly valve needs to adopt the ring sealing surface connection (RTJ) accordingly, and the sealing ring will also use octagonal steel gasket or It is an elliptical steel pad; in special cases, such as some flammable and explosive gases, or toxic and harmful gases, it is recommended to choose butt welding flange connection. Although welding is not convenient for maintenance in the later stage, welding is more reliable for safety reasons. a connection method. In general, for non-high-pressure or non-high-temperature media, raised-face flanges can basically meet most requirements.
Valve installation diagram
Based on the above, we can clearly understand the difference between the flange butterfly valve and the wafer butterfly valve. The difference between the two is actually very simple. From the perspective of the appearance of the valve, the main difference is the difference in the valve body. There is no flange hole in the outer contour of the wafer. Carefully check the valve installation schematic diagram, and you can also find that the construction and installation methods of the two valves with different connection structures are also different. The bolts go through and fasten the connection between the two. For the wafer butterfly valve, the stud bolts need to pass through the pipe flange, adjust the sealing surface of the butterfly valve, and tighten it.
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