1. Divided according to the chemical industry (HG) standards: whole flanges (IF), threaded flanges (Th), plate-type lap joint flanges (PL),焊接 neck flanges (WN), socket weld flanges (SO), socket welding flanges (SW), blind flanges with welding neck (PJ/SE), blind flanges with flat welding neck (PJ/RJ), lined flange covers (BL(S)), and flange covers (BL) [2].

2. Categorized by petrochemical (SH) industry standards: Threaded Flange (PT), Weld Neck Flange (WN), Socket Weld Flange (SO), Blind Flange (not specified), Lug Flange (LJ), Flange Cover (not specified).

3. Divided by JB industry standards for machinery: Full Flange, Weld Neck Flange, Plate Flat Weld Flange, Weld Neck Ring Type Joint Flange, Flat Ring Type Joint Flange, Bevel Ring Type Joint Flange, Flange Cover.

4. Categorized by country (GB) standards: Flanged Joints, Threaded Flanges, Weld Neck Flanges, Socket Weld Flanges, Blind Flanges, Ring Type Joint Flanges with Neck, Plate Type Weld Neck Flanges, Ring Type Plate Flanges, Plate Flanges with Ring, Flange Covers.