There are many single-layer, double-layer, cast iron covers, ductile iron covers, composite covers, cement concrete covers, etc., where the ductile iron covers are the most widely used.

Ductile Iron Manhole Cover Grade Marking Set Lightweight Type Q Road or parking place where the vehicle is forbidden to enter the green, corridor, bike lane or sidewalk Ordinary P steam 10 and below. Used to cover the road or home deep well defense, used to prevent pedestrians or objects fall. Generally divided into round and square, in the urban areas of the road, the general use of circular, because the circular covers are not easy to tilt, to better protect the safety of pedestrians and vehicles. The use of a circle is mainly due to the fact that the circular covers are passing through each of their diameters in the same length, so that if the covers are rolled by the passing vehicle, the diameter of the covers will be slightly higher than the lower Wide, covers will not fall into the wellhead. And if the square is used, because the diagonal of the square is significantly longer than each of its sides, such a well is rolled, it is easy to fall along the diagonal direction of the wellhead, resulting in security risks. If the wellhead is rounded or significantly smaller than the manhole, the square covers will not fall into the well. Here is a matter involving the maximum use and savings of a material. The use of the wellhead depends on the size of the wellhead, and if it is necessary to install a square well above the wellhead, it is more effective to use a circular cover than to use the material and the utility value. To ensure the safety of the wellhead. And in the countryside and the use of cable wells, the general use of square, which can better prevent the introduction of rain and other liquid.