1. According to the standard of mechanical industry, flange types are: plate type flat-welded flange, butt-welded flange, integral flange, butt-welded ring-plate type loose sleeve flange, flat-welded ring-plate type loose sleeve flange, flanged ring-plate type loose sleeve flange, flange cover.
2. Flange type according to the chemical industry norm: plate flat welding flange (PL), with flat welding neck flange (SO), integral flange (IF), threaded flange diameter (Th), with (WN) butt welding flange, socket welding flange (SW), the butt welding ring loose flange (PJ/SE), flat welding ring loose flange (PJ/RJ), flange cover (BL), lining flange cover (BL (S)).
3. According to the national standard, flange types are: plate type flat welding flange, neck flat welding flange, neck butt welding flange, integral flange, threaded flange, neck socket welding flange, butt welding ring neck loose sleeve flange, butt welding ring plate type loose sleeve flange, flanges ring plate type loose sleeve flange, flanges.
4. According to the standard of the petrochemical industry, flanges can be divided into flat-welded flanges (SO), butt-welded flanges (WN), threaded flanges (PT), socket welded flanges (SW), loose sleeve flanges (LJ), and flange caps (not specified in the table).