Lug Vulcanized Butterfly Valves are generally preferred because they are cheaper than other valve designs and need less support because they are lighter. The disk is placed in the center of the pipe. A rod passes through the disk to an actuator outside the valve. Rotating the actuator rotates the disk parallel or perpendicular to the flow. Unlike a ball valve, the disk is always in the flow, thus causing a pressure drop even when open. This product is available in Ductile Iron Stainless Clapper is produced.