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Why Are Manhole Covers Round?

Jun. 05, 2020

Aluminum Round Manhole CoverThe manhole cover is our common existence, and it can be seen everywhere when walking outside.  Due to different functions of the manhole cover, "electricity", "dirty" and "rain" are written on it and various symbols are drawn on it.

But no matter how many use the manhole cover has, the shape of the manhole cover is basically a circle.  Have you ever wondered why the manhole cover has to be round?

The problem of the manhole cover being round can be traced back to France in the 13th century... When France was building ancient Paris, it used around discus as the manhole cover for the sewer. Later, the Roman Empire used French sewer technology to build a Roman city. Later, major cities around the world successively adopted Roman sewer technology. As a result, the round manhole cover seemed to become a conventional thing.  In fact, the circular manhole cover has many advantages~!


Not easy to fall

Round, each radius from the center to the edge has the same length.

In this way, when the manhole cover is rolled up by the passing vehicle, its diameter will be slightly wider than that of the lower wellhead, and the manhole cover will not fall into the wellhead.

If a square is used, the diagonal of the square is significantly longer than each of its sides, so that when the manhole cover is rolled up, it is easy to fall into the well along the diagonal direction of the wellhead, causing potential safety hazards.


Not easily damaged

The circular force is uniform and can withstand loads from uncertain directions.  When the wheels are rolling, the manhole cover is still flat. If it is other polygons with corners, it is easy to be lifted, and its diamond corners are also easy to wear and tear, which is easy to damage and cause danger.


Easy to open and safer

When repairing the wellhead, the round shape is easy to open and also safer.  During maintenance, there will be no edges and corners that will scratch or cut the maintenance workers or tools.


Sturdy and wear-resistant

The round manhole cover is more durable and less susceptible to external damage.  No matter from which direction the wind and sand debris blows, it is easy to pass along the tangent direction of the garden surface, and only a small part is affected.


save costs

Aluminum Round Manhole Cover will achieve maximum utilization and saving of materials.  For manufacturers, manufacturing a round manhole cover is much easier than manufacturing a square manhole cover.  And the circular manhole cover can achieve the maximum utilization and saving of materials.  Under the same perimeter, the area of the circle is the largest, which means that under the same wellhead area, the circular manhole cover is the most material-saving.


Easy to handle

A custom aluminum round manhole cover is convenient for handling. Since the manhole cover is generally a heavy heavy iron block, which is made into a round shape, if it is damaged or needs to be replaced, the maintenance worker only needs to roll the manhole cover to move it.

Of course, in real life, we have also seen square manhole covers.  But we will still find that the manhole covers on the road are basically round, and the square manhole covers are generally water meter manhole covers and the like.  The circular manhole cover is mostly because of its safety and cost-saving.