1. According to the chemical industry standard (HG), it is divided into: integral flange (IF), threaded flange (Th), plate flat weld flange (PL), butt weld flange with neck (WN), flat weld flange with neck (SO), socket weld flange (SW), butt weld ring loose flange (PJ/SE), flat weld ring loose flange (PJ/RJ), lining flange cover (BL (S)), flange cover (BL).
2. According to petrochemical (SH) industry standards: threaded flange (PT), butt welding flange (WN), flat welding flange (SO), socket welding flange (SW), loose flange (LJ), flange cover (not note).
3. According to the mechanical (JB) industry standard: integral flange, butt welding flange, plate flat welded flange, butt welded ring plate loose flange, flat welded ring plate loose flange, flanging ring plate loose flange, flange cover.
4. According to the national (GB) standard: integral flange, threaded flange, butt welding flange, flat weld flange with neck, socket weld flange with neck, butt weld ring with neck loose flange, plate flat welded flange, butt welded ring plate loose flange, flat welded ring plate loose flange, flanging ring plate loose flange, flange cover.