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；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（>10%），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材。
　　球墨铸铁管的设计要求
　　1、管道的埋设深度应根据冰冻程度、外部荷载与其它管道交叉等因素确定。在一般情况下，埋设深度可在冰冻线以下0.2米处，并符合如下条件：当管径大于100mm时，管顶最小埋深为1.20米。
　　2、设计沟槽底宽一般为管外径加0.5米，并根据土质状况，确定开挖坡度（i），绘制沟槽剖视图。
　　3、球墨铸铁管与其它管材一样，均匀流的沿程水头损失也为hf=λ/dv2/2g，所不同的只是"λ"（水力摩阻系数），即水头损失可按原铸铁管局部阻力损失计算。在设计中，当预计有使水体流速发生突变变化的可能时，应考虑水锤压强，可按水力学有关公式进行计算。
　　球墨铸铁管的安装要求
　　1、施工前，对管材、管件、橡胶圈等做一次外观检查，发现有问题的均不能使用。
　　2、管道安装一般采用滑入式"T"型接口，只要将插口插入承口就位即可。施工实践证明，这种接口具有可靠的密封性、良好的抗震性和耐腐蚀性；操作简单、安装技术易掌握；改善劳动条件。是一种比较好的接口形式。
　　球墨铸铁管的出现为我国供水事业提供了一种性能优良的新型管材。为了在工程中更好的应用球墨铸铁管，设计与施工人员应熟悉球墨铸铁管的特性，不断地发现问题并加以解决，使设计更加合理、施工更加规范，使新型管材在供水工程中发挥更大的作用。


　　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 decreased, the pipe material possesses strength, high elongation, impact resistance, corrosion resistance, good sealing; 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 greater extension rate (> 10%), the pipeline of flexibility is good, in the underground pipeline can work with the pipeline and the surrounding soil, improve the pipeline by the stress state, so as to improve the reliability of the network operation. Therefore, Chinas water industry usually taking ductileironpipe as head of material.

　　The design requirements of ductile cast iron pipe

　　1, the buried depth of pipeline shall be determined according to the degree of freezing, external load and other factors such as pipeline crossing. In general, the buried depth can be in frozen 0.2 meters below the line and meet the following conditions: when the diameter is larger than 100mm, tube top minimum buried depth is 1.20 meters.

　　2, the design of the bottom width of the trench is generally 0.5 meters outside the pipe diameter, and according to the soil conditions, determine the excavation slope (I), drawing the groove profile view.

　　3, ductile cast iron pipe and other pipe like, uniform flow of water head loss along the way for lambda hf= /dv2/2g. The difference is just "lambda" (hydraulic friction coefficient) and the head loss can be according to the original cast iron pipe local resistance loss calculation. In the design, the water hammer pressure can be calculated according to the hydraulic pressure.

　　The installation requirements of ductile iron pipe

　　1, the construction of the pipe, pipe, pipe, rubber ring, and so do an inspection, found that the problem can not be used.

　　2, pipeline installation generally use the slide type "T" interface, as long as the socket is inserted into the socket can be in place. The construction practice proves that this kind of interface has a reliable sealing, good earthquake resistance and corrosion resistance, simple operation, easy installation technology, improving working conditions. Is a relatively good interface form.

　　Appearance of ductile iron pipe provides a new pipe with excellent performance for Chinas water supply industry. Characteristics to the better application of nodular cast iron pipe, the design and construction personnel should be familiar with nodular cast iron pipe, continue to find problems and resolved to make the design more rational and the construction is more standardized, the new pipe in water supply project play greater role.