Flange Dimensions
ANSI B16.1 Cast Iron Flanges
Dimensional standards for cast iron pipe flanges and flanged fittings
ASME/ANSI B16.1 covers cast iron pipe flanges and flanged fittings in Class 25, 125, and 250 designations. These flanges are commonly used in water distribution, HVAC, and low-pressure steam applications. Class 125 flanges feature flat face (FF) configurations, while Class 250 flanges use raised face (RF) designs for improved gasket seating. Select a category below to learn more about each configuration.
