A wafer-pattern butterfly valve is a type of flow control device used in pipelines to regulate or stop the flow of fluids. It’s called “wafer-pattern” due to its compact design, which fits between flanges without the need for additional bolts or flange gaskets. The valve comprises a disc, which pivots on a central axis within the pipeline to control the flow. When the valve is open, the disc is parallel to the direction of the flow, allowing fluid to pass through; when closed, the disc rotates perpendicular to the flow, blocking it.

These valves are commonly used in various industries, including oil and gas, water treatment, and manufacturing, due to their lightweight construction, ease of installation, and efficient flow control capabilities. They are often preferred for applications where space and cost are critical factors. However, their design may have limitations concerning pressure and temperature ratings compared to other valve types like lug or flanged butterfly valves.