A lug type butterfly valve is a type of butterfly valve that has threaded inserts, called "lugs," on the valve body. These lugs are used to attach the valve to the pipeline using bolts and nuts.

Lug type butterfly valves are often used in applications where the valve needs to be installed or removed from the pipeline without disrupting the flow of fluid. The lugs allow the valve to be installed using only two sets of bolts and nuts, which means that the valve can be easily removed for maintenance or replacement without having to disconnect the entire pipeline.

Lug type butterfly valves are available in a variety of materials, including stainless steel, cast iron, and PVC, and in sizes ranging from a few inches to several feet in diameter. They are commonly used in HVAC systems, water treatment plants, and the food and beverage industry, where they provide a reliable and cost-effective solution for controlling the flow of fluid.