Ductile iron is a kind of ductile iron material obtained by adding rare earth magnesium alloy and inoculation. The mechanical properties of ductile iron pipes are greatly improved. In order to distinguish ordinary cast iron, it is called nodular cast iron. It has the essence of iron and the performance of steel, high strength, high toughness, good corrosion resistance, good ductility, good sealing effect, simple installation, and strong internal and external pressure bearing capacity after installation;