Anti-theft: Standard anti-theft design, new anti-theft design, manhole covers and frames connected by bolts, integrated design. Level 4: (Low option - D400 type): Urban main roads, highways, expressways, and similar areas. Now, regarding the fire hydrant covers, they do have characteristics, especially for fire-resistant ductile iron covers. These ductile iron covers must be highly robust, whether in markets, ports, fishing boats, or any fire-related application, their pressure resistance is substantial.
Currently, there are five types of concrete drainage channels widely used in the market. One type is the metal cover concrete drainage channel, primarily used in industrial sites, roads, or airports. These channels have strong load-bearing capacity and are equipped with ductile iron guards. Different designs are adopted based on varying load-bearing capacities, providing better support and protection for the covers.
Generally, a complete manhole cover assembly consists of the manhole base and the cover. During usage, double-layer ductile iron manhole covers, due to being crushed by vehicles or heavy objects, may become loose between the base and the cover, creating gaps. The main features of the anti-subsidence ductile iron manhole cover are that the cover is directly placed over the well opening, transferring the weight the cover bears to the well body. Over time, the well body's sinking can lead to the manhole cover sinking as well.
The common coating for castings is anti-rust asphalt paint, of course, the surface of the ductile iron manhole covers is also treated with this anti-rust asphalt paint. Another reason for accepting the circular design is that the diameter of a circular manhole cover is the same on every side; as such, when vehicles pass over the manhole cover, regardless of the direction they are pressed from, the diameter of the ductile iron cover is wider than the manhole opening below.