Wafer butterfly valves allow bolts to pass straight through the butterfly valve so a single bolt passes through both flanges and the butterfly valve
Lugged butterfly valves require bolts to pass through the flange and screw into the butterfly valve. This needs to be done for the flanges on each side of the valve. This allows the butterfly valve to act as an end of line valve ie one side can be disconnected and the valve will prevent water passing through. This does require twice the number of bolts and the bolts need to be the exact length taking into account the thickness of the flange you are connecting the butterfly valve to. We recommend taking your butterfly valve and flange (or its thickness) into a hardware store and making sure you get the correct bolt type and length. Also get some washers as you can use them if your bolts are a bit too long.
Butterfly valves do not require gaskets.
|Butterfly Valve Wafer Cast Iron Epoxy Coated|
|Butterfly Valve Lugged Cast Iron Epoxy Coated|