Description
Manhole covers usually weigh more than 50 kg, partly because the weight keeps them in place when traffic passes over them, and partly because they are often made out of cast iron, sometimes with infills of concrete. This makes them inexpensive, strong, and heavy. A manhole cover sits on metal base, with a smaller inset rim which fits the cover. The base and cover are sometimes called "castings," because they are usually made by a casting process, typically sand casting techniques.
The covers usually feature "pick holes," into which a hook handle tool is inserted to lift them. Pick holes can be concealed for a more watertight lid, or can allow light to shine through. A manhole pick or hook is typically used to lift them, though other tools can be used as well, including electromagnets.
Although the covers are too large to be easily collectible, their ubiquity and the many patterns and descriptions printed on them has led some people to collect pictures of covers from around the world.
Despite their weight and cumbersome nature, manhole covers are sometimes stolen, usually for resale as scrap, particularly when metal prices rise.
Read more about this topic: Manhole Cover
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