CONNECTION DESIGN FOR BUTTERFLY VALVE REGENT Butterfly valves can be connected to a piping system in different ways. The most common methods are wafer type or lug type Wafer-style A wafer-style butterfly valve is the most economical version and it is sandwiched between two pipe flanges. This valve may or may not have flange holes outside of the valve body. The pipe flanges are connected through long bolts that cross the entire valve body. The sealing between the valve and pipe flanges is accomplished via gaskets, O-rings, and flat valve faces on both sides of the valve. This type of connection is designed for sealing against bi-directional differential pressures and to prevent backflow in systems designed for universal flow. Lug-style The lug-style butterfly valve has threaded inserts (lugs) outside the valve. Two sets of bolts connect pipe flanges to each side of the bolt inserts without nuts. This design enables the disconnection of one side without affecting the other for dead-end service. Lug-style butterfly valves used in dead end service generally have a lower pressure rating. The lug-style butterfly valves, unlike the wafer-style, carry the weight of the piping through the valve body.