(1) the nature of the conveying medium, general media, special media, toxic media, flammable and explosive media.
(2) According to the parameters of the medium, operating pressure, operating temperature, in the case of the medium is determined, according to the operating temperature of the medium and operating pressure to determine the nominal pressure PN of the flange.
(3) According to the place of use, connection conditions to determine the way of the flange and the tube connection and sealing surface form.
(4) Determine the flange specification according to the connected object.