What Is a Manhole Cover?
Jun. 22, 2021
What Is a Manhole Cover?
Before understanding the reasons why manhole covers are mostly round, we need to understand the basic facts to answer this question. What is a manhole cover?
Since the manhole cover is usually made of concrete, cast iron or a combination of concrete and iron, the manhole cover is manufactured for the safety of anyone passing over the sewer hole. At the same time, the standard manhole cover size is designed to fit a person's size, because its second use is to pass it, technically trained people can pass it when the sewer needs maintenance or installation in underground pipelines.
Through a metal base, the manhole cover is placed on it, and there is a smaller embedded edge to fix the manhole cover. To ensure safety, a manhole cover lock is installed to avoid removal due to any unofficial reasons.
Due to their common appearance, the first reason that manhole covers and derricks appear in a round shape is to resist the compression of the earth around them. Secondly, manufacturers will also find that it is easier to manufacture compared to square or rectangular manhole covers because they do not require the manhole covers to be arranged at an angle, while taking into account that the manhole covers will be heavy when moved from one place to another.
However, the main purpose of the manhole cover is preferably round is to prevent it from falling into the circular hole. All manholes, whether they are sewers or sewers, will form a "lip" at the edge of the hole, the size of which is smaller than the size of the manhole cover. Unlike the rectangular, square or oval shape, even if the hole is small, the manhole cover is slightly larger. Once the manhole cover is inserted into the hole obliquely, it may fall into the hole. If it is round, diagonal insertion is still inappropriate, which will be safer.
Why is the manhole cover round?
Round manhole covers are very common, and you may wonder why it is like that. This is mainly because a round manhole cover may not slide into the hole even if it is pushed obliquely. Unlike a rectangular, square or oval manhole cover, it may slide into the hole if it is placed in the wrong position.
In addition, the round manhole cover also has the advantage of resisting on Earth’s compression around it which also explains the technical and practical reasons why the manhole cover should be designed to be round.
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