Ductile iron manhole cover is a type of ductile iron product. Ductile iron obtains spherical graphite through spheroidization and inoculation treatment, effectively improving the mechanical properties of cast iron, especially improving plasticity and toughness, thereby obtaining higher strength than carbon steel. Ductile iron is a high-strength cast iron material developed in the 1950s, with comprehensive properties similar to steel. Based on its excellent performance, it has been successfully used to cast some parts with complex stress, high requirements for strength, toughness, and wear resistance. Ductile iron has rapidly developed into a widely used cast iron material, second only to gray iron. The so-called "replacing steel with iron" mainly refers to ductile black cast iron.
Spherical black cast iron manhole covers are generally divided into circular and square types. In urban road management, circular manhole covers are generally used because they are not easy to tilt and can better protect the safety of pedestrians and vehicles. When using a circle, the main consideration is that the length of each diameter of the circular manhole cover passing through its center is the same. This way, if the manhole cover is rolled up by a passing vehicle, regardless of how it is rolled up, its diameter will be slightly wider than the lower wellhead, and the manhole cover will not fall into the wellhead.
If a square is used, because the diagonal of the square is significantly longer than the length of each side, such manhole covers can easily fall into the well along the diagonal direction of the wellhead when rolled up, causing safety hazards. If the wellhead is circular or significantly smaller than the manhole cover, the square manhole cover will not fall into the well. This involves the maximum utilization and efficiency of a material
The issue of appointment. The use of the wellhead depends on the size of the wellhead. If a square manhole cover with an area much larger than the wellhead needs to be installed on it, then the utilization and practical value of materials are naturally not as effective as using a circular manhole cover directly. It not only saves materials for manhole covers, but also ensures the safety of the wellhead.