1. Categorized by the chemical industry (HG) standard: Flanged Joints (IF), Threaded Flanges (Th), Plate Flanged Socket Welding (PL), Weld Neck Flanged Joints (WN), Socket Weld Flanges (SO), Lap Joint Flanges (SW), Blind Flanges (PJ/SE), Welding Ring Lapped Flanges (PJ/RJ), Lined Flanged Covers (BL(S)), Flanged Covers (BL) [2].

2. Divided according to the petrochemical (SH) industry standards: threaded flange (PT), weld neck flange (WN), flat welding flange (SO), socket welding flange (SW), loose joint flange (LJ), and flange cover (not specified).

3. Divided by mechanical (JB) industry standards: Full Flange, Weld Neck Flange, Plate Welding Flange, Weld Neck Ring Type Joint Flange, Flat Ring Type Joint Flange, Bevel Ring Type Joint Flange, Flange Cover.

4. Divided by national (GB) standards: Weld Neck Flange, Threaded Flange, Socket Weld Flange, Blind Flange, Lap Joint Flange, Flanged Socket Welding Flange, Plate Flange, Flanged Ring Plate Flange, Flat Ring Plate Flange, Flanged Ring Plate Flange with Bevelled Edges, and Flange Cover.