... .Flange Material: carbon steel flange, alloy steel flanges, stainless steel flanges Steel etc. 1,Flange classification (1)According ... (2)According to production methods ,divided into forging flanges, cast flanges, welded flanges, rolled flange (3)According to manufacturing standards , ... , metal rings connected surface 3, Chinese steel pipe flanges National Standards System GB 1) Nominal pressure: 0. ...