Flanged butterfly valve, generally the bolt hole is a through hole, which is slightly larger than the bolt, and is clamped by the flange; lug type, bolt hole, matching with thread, installed with full-threaded stud bolt, one side of the nut is removed, Twist the bolt into the valve’s bolt hole, then tighten the nut.
The lug butterfly valve has through holes and internal threads. If it is a through hole, the bolt will be long and run through it; if it is an internal thread, the bolt will be shorter and installed on both sides of the valve.Some small-diameter wafer butterfly valves have lugs, and some do not, depending on the design of each manufacturer. However, some large-diameter valves should have lugs.
There are two kinds of holes on the lugs, one is a through hole, which is called A type in China. Its function is to locate the valve pipe coaxially during installation. Simply put, with these holes, the installation will be much easier. .The valve is fixed by the clamping force generated by tightening the two flanges to each other through bolts. Here, if a flange has eight holes, but the valve does not necessarily have eight holes, it is more common to see There are four holes, there are also two.The other is that the hole above the lug is a threaded hole, which is called LT type in China. Such a valve should be called a single-clamp valve correctly, because such a valve is generally installed at the end of the pipeline, and there is only one piece of the pipeline at this time. Flange, the valve is fixed on the pipe by the tightening force generated between the bolt and the threaded hole on the valve.