This Standard specifies cast iron pipe flanges of the nominal pressures 5K, 10K, 10K (thin type), 16K and 20K and of the nominal diameters 10A to 1500A (hereafter referred to as "flanges"), which are used for jointing steel pipes for fluid such as water, oil, vapour, air, gas, etc. and also used for cast iron pipes, pipe joints, valves and the like.