According to the raw materials, there are the following types of manhole covers applied at this stage: ductile cast iron manhole covers, composite manhole covers, silicon plastic manhole covers, polymer material pressure moulded manhole covers, etc.

1. Ductile iron manhole cover

There are two kinds of nodular cast iron manhole covers: nodular cast iron gray cast iron.

(1) Gray cast iron manhole cover:

It has a certain bearing capacity low price, but it has great ductility, easy to rust steal. It is mainly used in general load areas residential areas.

(2) Ductile cast manhole cover:

Compared with gray cast iron manhole cover, the bearing capacity is improved, the ductility of automobile sheet metal cutting raw materials is improved, the relativity is difficult to rust, the key is used in the main carriageway the road with extra large load. However, the price has been greatly increased, it is easy to be stolen because of its acquisition value.

In order to deal with the problem of theft, many locked ductile iron manhole covers have been developed designed. Although the anti-theft problem has been improved to a certain extent, some people steal the manhole cover after smashing it with sheet metal cutting method, because the universal lock key is selected, it is impossible to avoid technical professional theft. often because of the lock corrosion harm open. The cost of the project has soared further, causing difficulties in economic development application for customers.