Detailed machining drawings of butterfly valve, including general assembly drawing, calculation sheet, detailed list, machining drawing, technical requirements, surface treatment, etc., are very detailed and are used for actual production. It includes six different drift diameters, namely 80D, 100D, 125D, 200D, 300D and 450D. Butterfly valve, also called flap valve, is a regulating valve with simple structure, which can be used for low pressure pipeline medium