球墨铸铁管是以镁或稀土镁结合金球化剂在浇注前加入铁水中，使石墨球化，应力集中降低，使管材具有强度大、延伸率高、耐冲击、耐腐蚀、密封性好等优点的管件；内壁采用水泥砂浆衬里，改善了管道输水环境、提高了供水能力、降低了能耗；管口采用柔性接口，且管材本身具有较大的延伸率，使管道的柔性较好，在埋地管道中能与管道周围的土体共同工作，改善管道的受力状态，从而提高了管网运行的可靠性。因此，目前我国供水行业通常采用球墨铸铁管作为主管件。

　　Nodular cast iron pipe is a magnesium or magnesium rare earth with golden agent before pouring into the hot metal in the spheroidization of graphite, the stress concentration is reduced, so that the pipe has the strength, elongation rate is high, impact resistance, corrosion resistance, sealing good pipe; inner wall with cement mortar lining, improve the pipeline environment, improve the water supply capacity, reduce energy consumption; pipe with flexible joint and the pipe itself has larger elongation, the pipeline of flexibility is good, in the underground pipeline can work with the pipeline and the surrounding soil, improve the pipeline stress state, thereby improving the reliability of the network operation. Therefore, Chinas water industry usually taking ductileironpipe as a supervisor.