... , etc.. (2)According to production methods ,divided into forging flanges, cast flanges, welded flanges, rolled flange (3)According to manufacturing standards ,divided into ... , a, Nominal pressure: 0.1, 0.25, 0.6, 1.0, 1.6, 2.5, 4.0, 6.4, 10.0, 16.0, 25.0, 32.0, 40.0, Mpa b, The ...