This Standard specifies requirements for ductile iron pressure pipes centrifugally cast in moulds, and ductile iron fittings of nominal sizes up to and including DN 750.The specified pipes and fittings are intended primarily for conveying water under pressure, but they may be used for conveying sewage or other liquids.This Standard specifies classifications of pipe on the basis of the allowable operating pressure (AOP); however, Flange Class pipe has been specified for manufacture of flanged pipe with screw-on flanges. NOTE: Ductile iron is also known as spheroidal graphite iron, SG iron or nodular graphite iron.