... Steel Pipe Flanges and Flanged Fittings >ANSI B16.47A/B ,B16.36 b, The public diameter: 6 ~ 4000mm c, Flange structure ... .0, PN15.0, PN25.0, PN42 (main series) b, Series 2: PN0.25 PN0.6 PN2.5, PN4. ... structure: Integral flange Unit flange a, threaded flange b, welding flange, welding neck flange, welding neck flange ...