The manhole cover is made of ductile iron. These covers need to be heavy so that they do not fall off when the vehicle passes over them. Manhole covers typically weigh 100 pounds each. Some have open holes to allow water to enter the manhole. Others have hidden the pick-up holes, which do not go all the way through the lid or lift the handle, such as the pull handle or the ring handle. For safety reasons, manhole covers can be bolted to the frame. Manhole covers can also have washers on the bottom of the cover and be bolted to the frame, which is generally considered waterproof.
Manhole covers provide access to the underground world of sewers, water pipes, power / communication lines, pipes, etc. Manhole covers are an art form. They are usually “sanitary sewers” or “rainstorm sewers,” but they can basically be marked with any letter. Manhole covers come in different patterns / designs and can even be customized with logos if the city needs it. Next time you walk through a city and look down when you notice.

Designed for H-20 traffic loads
Standard font up to 26 “ID:
Sanitary or storm sewer
Standard 30 “ID:
Electrical, communication or telephone
Options:
Special font, locking option, bolted, waterproof
Round manhole cover and frame
Why are most manhole covers round? The manhole cover is circular because it cannot fall through its circular opening. The manhole cover is placed on the frame base; therefore, the diameter of the frame opening is smaller than the manhole cover. However, if turned diagonally in the hole, a square or rectangular manhole cover may fall from the opening. It is also easier to dig a round hole. Round covers are easier to machine on lathes. The round manhole cover can be rolled and moved more easily if needed.