Specifies the requirements for metallic butterfly valves with centred or eccentric disc, with centred or eccentric shaft, with metallic, polymeric, elastomeric or composite seating, with lined or unlined body, coated or uncoated, to be used in flanged or butt-welded piping systems for shut-off, throttling or flow control. Covers butterfly valves with nominal diameters DN 40 to DN 2000 and is applicable to valves of nominal pressure PN 2,5 to 50.