1. Divided according to the chemical industry (HG) standard: whole flange (IF), threaded flange (Th), plate flat welding flange (PL),焊接 neck flange (WN),焊接 face flange (SO), socket welding flange (SW), welding ring loose flange (PJ/SE), flat ring loose flange (PJ/RJ), lined flange cover (BL(S)), flange cover (BL) [2].

2. Divided by petrochemical (SH) industry standards: Threaded Flange (PT), Weld Neck Flange (WN), Slotted Flange (SO), Socket Weld Flange (SW), Lapped Flange (LJ), and Flange Cover (not listed separately).

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

4. Categorized by national (GB) standards: full face flange, threaded flange, weld neck flange, slip-on flange, socket weld flange, blind flange, flat焊接 flange, lap joint welding flange, raised face flange, flat焊接 face lap joint flange, beveled face flange, and flange cover.