The manhole cover is designed to be circular for the following reasons:
Prevent falling: Round manhole covers have no angle and will not fall into the well no matter how they are placed, while square or rectangular manhole covers may fall into the well if they are placed at the wrong angle, which is a safety hazard.
Easy to move: The round manhole cover can be easily moved by rolling, which is very convenient for workers when they need to inspect or repair the manhole cover.
Evenly withstands pressure: The shape of the round manhole cover allows the pressure to be distributed more evenly across the entire surface, which helps to reduce damage caused by uneven pressure distribution and increase the life of the manhole cover.
Adaptable: The round manhole cover is not limited by the size of the wellhead, and even if the wellhead size changes slightly, the round manhole cover can still maintain its position.
Material savings: Compared to other shapes of manhole covers, round manhole covers require less material in the manufacturing process, which reduces costs.
Reduced risk: Circular manhole covers are free of significant edges and edges, reducing the risk of injury to personnel or equipment during operation.
Yes, square and triangular manhole covers also exist.
Square manhole covers have been used in the past, but due to problems such as inconvenient installation and difficult transportation, they have gradually been replaced by round manhole covers. Triangle manhole covers are mainly used in special occasions, such as in some parts of Germany. This kind of manhole cover has the advantages of fast installation, light weight and high safety, especially suitable for occasions that need to be opened and closed frequently.
However, whether it is a square or a triangular manhole cover, they have certain limitations in practical applications, so when choosing the shape of the manhole cover, it needs to be comprehensively considered according to the specific use environment and needs.
Overall, the design of a round manhole cover offers a variety of advantages, including safety, practicality, and economy. This is also the reason why round manhole covers are widely used in many manhole cover designs.