Is a ductile iron manhole covers products. Ductile spherical graphite obtained through ball and inoculation. Effectively improved the mechanical properties of cast iron. In particular, to improve the ductility and toughness. Resulting in higher than carbon steel strength. Ductile iron is the 1950s developed a high-strength cast iron materials. Its overall performance is close to steel. It is based on its excellent performance. It has been successfully used to cast some of the complicated forces. Strength, toughness, wear resistance parts requiring high. Ductile iron has quickly become second only to gray cast iron, cast iron material is widely used. The so-called "iron and steel", mainly referring to ductile iron.

Manhole covers are generally divided into round and square. In terms of urban highways. Generally circular, because a circular covers easy to tilt. It can better protect the safety of pedestrians and vehicles. Circular, mainly on account of covers through its circular center of each length they are the same diameter. So if covers are passing vehicle from rolling when. Because no matter how rolled together. Its diameter will be slightly wider than the following wellhead. It covers not fall wellhead go.

If using a square. Because the square diagonally significantly longer than its length of each side. Such covers are rolled from time to time. It is easy to fall into the wells along the diagonal direction of the wellhead. Safety hazard. If the wellhead made circular or significantly less than the covers. Square covers will not fall into the well. Here involves a maximum use and conservation of a material problem. Covers are used depending on the size of the wellhead. If you have installed above an area much larger than the wellhead square covers. So the use of natural materials and practical value does not directly use the circular covers more effectively. It covers not only saves material. But also to ensure the safety of the wellhead.

The cable in the country and well utilized. Generally use the square. This can better prevent rainwater into the liquid.