what is the difference between a lug type butterfly valve and wafer type butter fly valve.
The difference between a Wafer and Lug type Butterfly valve is only the mounting scheme [1] and [2].
Lug type valve as the name suggests has lugs that are used to mount the valve to lugs that are attached the flanges on then ends of sections of pipe so that each length of pipe can be removed and replaced independently. Typically there are 8 or 12 lugs where 4 or 6 lugs are used to connect the each pipe section.
Wafer type valves don’t have attachment lugs, though them may have alignment lugs. They are sandwiched between the flanges on the ends two lengths of pipe. To replace either length of pipe requires shutting the system down.
