The butterfly valves not only used in the general industry widely,such as petrol, gas,chemical,or water treatment.but also used in cooling water system of power plant industry. wafer and flange are two kinds of connections. Flanged butterfly valves have flanges at both ends of the valve body, which are connected with pipe flanges. The wafer butterfly valve has no flanges on both ends of the valve body, only a few pilot bolt holes, and the valve is connected to the end flange with a set of bolts/nuts. The price of the wafer type is cheaper and the weight is more and lighter. When choosing imported valves, use the butt-clamp type as cheaply as possible.
Ⅰ. Brief introduction of wafer butterfly valve and flange-type butterfly valve:
- Wafer Butterfly Valve
The wafer butterfly valve (the valve itself cannot be flanged) is connected between two pipe flanges with double-headed bolts; the wafer butterfly valve is simple in structure, small in size, It is lightweight and consists of only a few components. And only need to rotate 90 ° can quickly open and close, a simple operation, while the valve has good fluid control characteristics.
- Flanged Butterfly Valve
Flanged butterfly valves are valves with flanges, and the flanges on both ends of the valve are bolted to the pipe flange. Wear-resistant sealing surfaces for long service life. Unique structure, flexible operation, labor-saving, convenient, not affected by the high and low media pressure.
Ⅱ. The difference between wafer butterfly valve and flanged butterfly valve:
1. Different connection methods
Wafer and flanged are two different connection methods.
- Wafer Butterfly Valve: There is no flange on the valve body, and the valve is connected between two pipe flanges with double-head bolts, that is, the two flanges clamp the butterfly valve in them, and then the bolts hold the two flanges in place.
- Flanged butterfly valve: the valve body with a flange, with bolts on the valve on both ends of the flange connected to the pipeline flange on it.
2. Different structure
Wafer butterfly valve with a longer bolt, and no flange itself, so generally do not install at the end of the pipeline and downstream need to dismantle the position, because in the dismantling of the downstream flange, the wafer valve will fall, so that the valve at both ends of the pipeline can not work properly, and flanged butterfly valve does not have such a problem, the flange body has a flange, and the pipeline flange pairing with a bolt connection, the nut locking, so that when one end is removed, the valve is connected to the pipeline flange, and the nut locking, so that when one end is removed, the valve is connected to the pipe flange. So when one end is removed, it will not affect the operation of the other end.
3. Different cost
The bolt length of the wafer butterfly valve is longer. Higher requirements for construction accuracy, if the two sides of the flange are not centered, the bolt will be subjected to greater shear force, resulting in easy leakage of the valve; compared to the clamped butterfly valve will be more convenient to disassemble some of the valves at a lower cost, but there is a disadvantage is that if a sealing surface problems, then both sealing surfaces have to be disassembled!
Ⅲ. The choice between the two:
But there are still some things to pay attention to in the design, for example, the valve bolts of the clamped type are generally longer, and under high-temperature conditions, the bolt expansion may lead to leakage, so it is not suitable for large pipe diameter under high-temperature conditions.
Another example is that the wafer butterfly valve generally can not be used at the end of the pipeline and the downstream needs to dismantle the occasion, because when the downstream flange is dismantled, the clamped valve will fall, in this case, it is necessary to do in addition to the short section to dismantle the flanged butterfly valves do not exist above the problem, but the cost will be relatively high.
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