For 2nd class building rain water pipes shall be of .............................finished painted.

cast iron is a group of iron- carbon alloys with a carbon content greater than 2%.[1] its usefulness derives from its relatively low melting temperature. the alloy constituents affect its colour when fractured: white cast iron has carbide impurities which allow cracks to pass straight through, grey cast iron has graphite flakes which deflect a passing crack and initiate countless new cracks as the material breaks, and ductile cast iron has spherical graphite ?nodules? which stop the crack from further progressing.