Circular ductile iron manhole covers are generally used in urban roads, and circular manhole covers are not easy to tilt, which can better protect the safety of passing pedestrians and vehicles. The main reason for using a circular manhole cover is to consider that each diameter length of the circular manhole cover through its center is the same, so that even if the manhole cover is tied up by the vehicle tire, its diameter will be slightly smaller than the following wellhead, and the manhole cover will not fall off the wellhead. Ductile iron manhole covers have the following characteristics 1.Convenient and beautiful The appearance of the spherical ink manhole cover is silver gray or dark gray line simple looks beautiful and generous product light weight to the installation and maintenance of great convenience 2. Good drainage effect Especially, after rain, the floor drain is better than others, suitable for the area of much more rain…