... 3.ISO9001:2008 Flange is a mechanical part which used for connecting pipe.Flange Type: Welded flange, Welding neck flange, Male ... flat, raised face,male and female, tongue and groove, rubber ring joint face, the lens surface and the diaphragm welded surfacee ... surface: flat, raised face, convex face, tongue and groove, ring joint faceFlange production standard Chinese Standard:GB/T9112-2000(GB9113 ...