... system: the German DIN (Soviet Union), the British Standard BS, French standard NF, Italian standard UNI, a, Nominal pressure: 0. ... b, The public diameter: 6 ~ 4000mm c, Flange structure type: welding, socket welding, threaded connection, loose, butt weld and blind flange d ... b, welding flange, welding neck flange, welding neck flange, socket weld flange with neck , slipon plate flange c, Loose flange ...