1. In accordance with the chemical industry (HG) standards: Overall Flange (IF), Threaded Flange (Th), Plate Flanged Socket Welding (PL), Necked Socket Welding Flange (WN), Necked Lap Welding Flange (SO), Socket Welding Flange (SW), Welding Ring Loose Fit Flange (PJ/SE), Lap Welding Ring Loose Fit Flange (PJ/RJ), Lined Flange Cover (BL(S)), Flange Cover (BL) [2].

2. Categorized by petrochemical (SH) industry standards: Screwed Flange (PT), Weld Neck Flange (WN), Slotted Flange (SO), Socket Weld Flange (SW), Lapped Joint Flange (LJ), Flange Cover (not specified).

3. By mechanical (JB) industry standards: full face flange, welding neck flange, flat welding plate flange, welding neck loose plate flange, flat welding loose plate flange, bevelled edge loose plate flange, and flange cover.

4. Categorized by national standards (GB): Overall flanges, threaded flanges, socket weld flanges, blind flanges with neck, socket-welding neck flanges, ring-type joint flanges with neck, flat welding plate flanges, ring-type joint plate flanges, flat welding ring plate flanges, bevelled ring plate flanges, and flange covers.