Butterfly valves are a cost effective valve option for larger pipe sizes. They are also easy to install by allowing them to be bolted between two flanges.
Wafer butterfly valves allow bolts to pass straight through the butterfly valve so a single bolt psses through both flanges and the butterfly valve. You need to make sure your bolts are long enough to pass through both flanges and the butterfly valve and enough thread for the nut.
Butterfly valves do not require gaskets.