Wafer and flange are two connection methods. Wafer type is cheap, the price is roughly 2/3 of the flange. When choosing imported valves, use the wafer type as much as possible, and the price is cheap. Lightweight.
Wafer type valves have longer bolts and require higher construction accuracy. If the flanges on both sides are not aligned, the bolts will be subjected to greater shearing force, and the valve is prone to leakage. Wafer-type valve bolts are generally relatively long. Under high temperature conditions, the expansion of the bolt may cause leakage, so it is not suitable for large pipe diameters under high temperature conditions.
In addition, wafer butterfly valves generally cannot be used at the end of the pipeline and downstream where it needs to be disassembled, because when the downstream flange is disassembled, the wafer valve will fall off. In this case, a short section must be made separately. In order to disassemble, and the flange type butterfly valve does not have the above problems, but the cost will be higher.
The wafer butterfly valve has no flanges at both ends of the valve body, only a few guide bolt holes, and the valve is connected to the end flange with a set of bolts/nuts. In contrast, disassembly is more convenient, and the valve cost is lower, but the disadvantage is that one sealing surface has a problem, and both sealing surfaces have to be disassembled. The flange type butterfly valve has flanges at both ends of the valve body, which are connected with pipe flanges. The seal is relatively more reliable, but the valve cost is relatively high
Butterfly valve installation and maintenance
1. During installation, the valve disc should be stopped in the closed position.
2. The opening position should be determined according to the rotation angle of the butterfly plate.
3. For the butterfly valve with bypass valve, the bypass valve should be opened before opening.
4. The installation should be carried out according to the installation instructions of the manufacturer, and the heavy-weight butterfly valve should be installed with a firm foundation.
5. The butterfly plate of the butterfly valve is installed in the diameter direction of the pipeline. In the cylindrical passage of the butterfly valve body, the disc-shaped butterfly plate rotates around the axis, and the rotation angle is between 0° and 90°. When the rotation reaches 90°, the valve is fully opened.
6. If the butterfly valve is required to be used as a flow control, the main thing is to correctly select the size and type of the valve. The structure principle of butterfly valve is especially suitable for making large-diameter valves. Butterfly valves are not only widely used in general industries such as petroleum, gas, chemical, and water treatment, but also used in cooling water systems of thermal power stations.