The types of pipe flanges can be distinguished, including:
Flange types based on ANSI size, for example: ANSI # 150, ANSI # 300, ANSI # 600 and so on.
Flange type based on face type on the pipe, for example: flat face type, type raised face and ring type joint.
Flange types based on their shape according to ANSI.
Ansi WNRF flange type
Ansi PN-16,10,25,40
NS Flange Type, STD