Why are manholes round?

Why was the round shape chosen for the hatches?

There are a lot of answers to the question why the hatches are round, but the following assumptions are the most reasonable:

In our country, well tunnels and sewer pipe sections are round, so it makes no sense to make covers of other shapes. At the same time, foreign experience knows many exceptions: for example, square manhole covers can be found in some cities of the Czech Republic and China, although they do not correspond to the shape of the wells they cover.
Round sewer manholes will never fall into a well, which means they are best suited to perform their protective function. And all because the diameter of the covering circle is always greater than the diameter of the well itself, and square covers can enter it, for example, at an angle.
Hatches are made round in order to reduce the cost of their production. This is due to the specifics of the equipment: in order to make a round cap, less material is needed. The standard hatch width norms are 600 mm, for a circle it will be a diameter, and for a square it will be a side, so the area of a square hatch will be 0.36 square meters, and a round one will be 30% less.
The manhole cover is round because it is convenient to carry. In most cases, manhole covers are made from a grill (grey cast iron), which is obtained by melting various scrap metal. The weight of one cover varies from 50 to 110 kg. It is quite difficult for one person to move the manhole cover from one place to another, and thanks to its round shape it can be rolled.
It is convenient to mount and dismantle hatches that are not square, namely round hatches, since load concentration points go along the entire circumference of the cover, while for square or rectangular hatches, only corners will have such points. That is why the necks and, accordingly, the lids for the jars are made round.

In fact, discussions about the shape of manholes may seem meaningless to many.

However, few people know that such an unimportant question can take anyone by surprise when ... applying for a job! And don't be surprised

This type of interview question is not uncommon. HRs among themselves refer it to "cases", that is, keys with which you can give a more accurate assessment of some qualities and abilities of applicants.

This practice is used mainly during interviews for applicants applying for high positions. In this way, the fact of how a person behaves in case of force majeure, what speed of thinking he has, whether he knows how to use non-standard approaches, and so on, is evaluated.

Riddles and secrets on the lids

Determine the manufacturer's data ... It sounds so boring that it even reduces the cheekbones! In fact, this work is extremely exciting and painstaking, sometimes comparable to an exciting detective investigation. It used to be simplicity and grace in the world! All the names of cities and manufacturers were written directly on the cast iron. Therefore, many have survived to our time in a more or less readable form.

However, somewhere in the early 60s of the last century, the lafa ended, and foundries stopped providing such courtesy to their descendants-collectors. Since that time, obscure abbreviations and logos appear on the covers, and work begins on their recognition and attribution. I’m already silent about such mystery hatches, on which there is not a single word, not a single letter ...

Do you know how long it took me to identify the campfire logo? But now I am proud to present to you - this is the sign of the Kusinsky foundry and machine-building plant, which is located in the Urals, in the Chelyabinsk region.But look: with a quality mark, a “sun” pattern and an emblem - a wonderful elephant! This is Moscow, the logo of the Vodopribor plant.

But these are all simple tasks. But the problem of the designation of the BSRZ was solved by the bright heads of the whole community of Lukovologists, but the mystery was not resolved. The first suspicions fell on the Balakovsky ship repair, then on the Berdichevsky machine-tool repair plant. Experienced connoisseurs doubted: maybe it was the Baltic or Blagoveshchensk plants?

Or, SMR. What is it and where to look for it? Who is the parent of the foundling, marked with the letters CHZZ - Chelyabinsk plant? PZA is Penza? Who is hiding behind the abbreviation of this old man SHK? The city is not stingy, throwing riddles.

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In each country, the development of sewerage systems took place in different ways, but the only common feature has always been the need to install sewer manholes.

The first manholes appeared together with the emergence of public utilities back in the 30s of the 19th century: then manhole covers had different shapes, but preference was most often given to round-shaped covers. Currently released, sewer manholes are round, and not of a different shape. This feature, in spite of everything, remained unchanged. But why exactly round?

Manhole covers are subdivided depending on their purpose. All of them have different patterns and embossing. On the old hatches you can see already outdated images of coats of arms, all kinds of drawings and inscriptions.

Modern manhole covers carry information about the manufacturer, serial number and date of manufacture. Some companies intentionally replace old sunroofs with new ("decorative") ones near their offices, and usually put images of their logos on the covers.

Security Considerations

Despite their small dimensions, the covers weigh about 50 kilograms, because they are made of cast iron. And the weight of products located on the roadway exceeds 78 kilograms - after all, they must withstand the weight of passing cars. According to the rules, hatches located on the sidewalks must carry loads of up to 12 tons, and those intended for installation on the road - up to 25 tons.

Given the significant weight of the covers, it is very important to follow safety rules while working in the sewer well. If the product falls into the hatch on the heads of the workers, a tragedy cannot be avoided.

Luckily, the round lids are designed to never fall down the well. Products that have the shape of a square or rectangle can easily fall off, because their diagonals are always larger than either side.

Geometry patterns

There are thousands of them. Vintage and new. Cast iron, steel and polymer. Flat, slightly convex and with a pronounced domed structure, manhole covers of wells lie on the streets of Saratov. And it just seems that they are all the same.

Look how different they are: this one, with pimples, looks like a mine - a formidable weapon of World War II - horned death, which often surfaced on Kronstadt raids during the blockade of Leningrad and on the seas of the USSR during the mine war.

And here is the old hatch. Old because domed. This is a tradition from the pre-automobile era.

And this one, very old in appearance, was found not far from the Glebuchev ravine and surrounded by ancient buildings.

Rarity - so immediately and respectfully I wanted to call it. And is it true, because it looks like a round shield of some invincible Olaf? Everything is like the militant Vikings - a socket and an umbon in the center ...

My husband shakes his head doubtfully, he thinks that the handsome man is just a hatch-shifter. But I liked it - albeit the wrong side, but - miraculous.

Well, this one, does it really look like a shield?

Look, a real alpha male of the hatch kingdom.But why is this absolutely bald brutal all in cracks? What brought him to this state? Casting of ugly quality, or did it get hit by the heels of pedestrians in alliance with ruthless time?

There are completely without a pattern, but there are decorated with concentric circles, stripes, waves, pimples, cells ... A pleasant find is the "rhombus" pattern - also a rarity for our streets. I would like to show you all of them, without exception, because even the most modest of them are interesting in their own way. It took a long time to choose. Look what beauty I met!

First, you look with enthusiasm at every sewer hatch you meet, take a photo lovingly, and then you get fed up and already start to turn up your nose at some instances. As if from russula growing next to the royal family of porcini mushrooms. There comes a moment when you walk one, the second street - and not a single sample with a new design.

And although it is sad to think that the number of their varieties is not infinite, but I still have a lot ahead - I have not yet met cast-iron manhole covers with such an unusual and beautiful geometry of patterns as scales and trapeziums. But is the pattern of chrysanthemum, compass, steering wheel worse?

By the way, now many have begun to get involved in the search for interesting manhole covers, and on the Internet there are many pages with photo collections dedicated to them.

Possible problems

During the deepening of the well, some problems may arise. For example, you may encounter some difficulties when lowering new rings into the shaft. There are several ways to deal with this problem.

The easiest way is to drill holes with a diameter of 150-200 mm along the outer perimeter of the upper ring. The depth of the hole should be as deep as possible. Therefore, it is necessary to prepare not only the drill, but also several nozzles for it. For the manufacture of nozzles, a thick-walled pipe is ideal. During work, it will not twist and deform. The length of the finished drill should be about 4 m.

Drilled holes should be abundantly moistened with water. If possible, then equipment is used to shrink the rings, for example, a construction truck crane. If this is not possible, then several men of strong physique can easily cope with this task by jumping on the end of the upper ring.

There is another way to lower the ring. For it you will need aspen boards and bars. The use of aspen is the main condition, since it does not rot in water. Boards should have a length corresponding to the distance from the bottom ring to the bottom. A circle is constructed around the perimeter of the lower ring from the boards.

So that the soil does not squeeze them out, a double belt is installed from a thick aspen beam. The design must be securely fastened and be a single whole. If all the work is done correctly, then a new aspen ring will be installed in the well.

Diggers working on the deepening of the well, another nuisance lies in wait - quicksand. This is a serious danger in the way of earthworks. To get through the dangerous area faster, you will have to speed up the work and take out more soil. An additional ring must be used as a load. If the quicksand is small, then it is possible to quickly install the rings and strengthen the structure.

During the work, you need to be extra careful and use additional protective equipment so that the lives of people working at the bottom are safe

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Why was the round shape chosen for the hatches?

There are a lot of answers to the question why the hatches are round, but the following assumptions are the most reasonable:

In our country, well tunnels and sewer pipe sections are round, so it makes no sense to make covers of other shapes.At the same time, foreign experience knows many exceptions: for example, square manhole covers can be found in some cities of the Czech Republic and China, although they do not correspond to the shape of the wells they cover.
Round sewer manholes will never fall into a well, which means they are best suited to perform their protective function. And all because the diameter of the covering circle is always greater than the diameter of the well itself, and square covers can enter it, for example, at an angle.
Hatches are made round in order to reduce the cost of their production. This is due to the specifics of the equipment: in order to make a round cap, less material is needed. The standard hatch width norms are 600 mm, for a circle it will be a diameter, and for a square it will be a side, so the area of a square hatch will be 0.36 square meters, and a round one will be 30% less.
The manhole cover is round because it is convenient to carry. In most cases, manhole covers are made from a grill (grey cast iron), which is obtained by melting various scrap metal. The weight of one cover varies from 50 to 110 kg. It is quite difficult for one person to move the manhole cover from one place to another, and thanks to its round shape it can be rolled.
It is convenient to mount and dismantle hatches that are not square, namely round hatches, since load concentration points go along the entire circumference of the cover, while for square or rectangular hatches, only corners will have such points. That is why the necks and, accordingly, the lids for the jars are made round.

In fact, discussions about the shape of manholes may seem meaningless to many.

However, few people know that such an unimportant question can take anyone by surprise when ... applying for a job! And don't be surprised

The first victim of an insidious trap

Alexandra Kapitonova, a young bourgeois from the province of Tver, on that day suddenly felt an urgent need for "an elegant and good women's dress of the latest cut from foreign and the best Russian fabrics." Full of the most serious intentions, she hastily went to the capital.

But the trip to the Moscow "boutiques" of the early 20th century ended for her before it even began. Immediately upon arrival, the poor thing, according to the reporter, "slightly suffered", falling into a round trap at the famous Moscow store "Muir and Merilize", thus becoming the first victim of the treachery of hatches.

However, we will deal with horror stories related to cast-iron rounds later, but for now, here's a question for filling: why is the sewer cover covering the manhole shaft round, and not oval or, for example, square?

Geography of cast-iron manholes in Saratov

There were many sacred places where brand new cast-iron manholes appeared in the 20th century. Indeed, by and large, any enterprise with a foundry could make them. Hatches of manholes did not hesitate to make even at the factory, famous for centuries of tradition, which produced highly artistic Kasli castings. From their native places, newborns moved to a new place of residence, sometimes hundreds of kilometers away, where they regularly carried out their inconspicuous service.

A short raid on the rear of the parental home in Saratov immediately discovered many such nomad hatches. Their logistics defies explanation.Cast-iron covers came to our city from Rzhev, Voronezh, Kerch, Sverdlovsk, Yaroslavl, Lipetsk, Rostov-on-Don, Novocherkassk, Kharkov and a bunch of other cities, I didn’t even suspect the existence of some.

For example, take Andreapol. I don’t know how it will be for you, but with only one name, I immediately heard the music of the waves of the Black Sea and saw the white antique columns left over from the ancient Greek policy. But no, this is a city from the Tver region.

Tearing up a pile of dung, the rooster found a pearl grain ... That's how I found this miracle from Tambov with a big star.

Once I came across an old, very large and convex hatch. There was something written on it, but it was impossible to read what it was. I guarded the lid, trying to guess the right direction of the light. And warned! After a summer rain, the rays illuminated the letters and I read - Peskovsky Plant.

He is Peskovsky because he stood on the Peskovka River in the Kirov Region. Cast iron has been produced since 1771. But now the plant no longer exists - it went bankrupt, but was one of the most prosperous and in its own way unique among other iron foundries in Russia.

Look at the unusual shape of this hatch from Leningrad. I came across another similar one, also consisting of four segments, but this one was without any identification marks. However, it is known that such a specific form of lids - it is called a manazhnitsa - was in very, very old hatches made in the late 19th and early 20th centuries. Now such a rarity.

Somehow I came across a pretty hatch of the Kamensky foundry. I began to puzzle over where this Kamenka was. Ural? Ukraine? Then I found the same cover in the blog of the famous Saratov local historian Denis Zhabkin, according to which it turned out that they were made in the village of Kamenka, Krasnoarmeysky district, Saratov region.

It may very well be, because according to data from the Internet, an iron foundry was created there in 1897, later transformed into a factory. And, besides, somewhere near the territory of the village there was a camp site of Kamenlag, and the foundry was the hardest work, in which prisoners were often involved.

By the way, how are things going with the sewer manholes of local production? Haven't I come across these? Of course there were some! We will talk about those that were made directly in Saratov next time, and so we came across manhole covers from Volsk (there are many of them!), Balashov, Kalininsk, Petrovsk.

And, perhaps, here is another hatch that arrived from Tbilisi. He is not particularly handsome, but, I'm afraid, no one will see him now: the road was being patched and the workers were ruthlessly covering it with asphalt chips. Now you won't scratch. Only a piece sticks out, and if I didn’t know where to look, I would never have found it.

Sometimes life gives us funny surprises. I started my story with a beautiful hatch from Spain. How was I to know that one day, on a Saratov street, a distant country would send its greetings to me with a hatch made in Barcelona.

Well, now the number of incomprehensible things in our world has somewhat decreased! And you, friends, now homework.

Do not pass indifferently by, take a closer look at the sewer manholes. To the variety of patterns on them, to the way their constituent elements repeat and alternate, how they line up according to the laws of symmetry into very simple and more complex versions of patterns. How many cover designs did you see on the streets of your city? Try to read their biography from the inscriptions on the cast-iron mugs. And we will meet soon and continue ...

Category: Russia

Interesting facts

In the world, cases of using caps of a different shape are known. So, for example, in the American city of Nashua, you can still see sewer wells covered with triangular covers. Their sharp corners indicate the direction of the flow of wastewater, and until recently, this helped repair crews to navigate well. But today their use is recognized as unsafe, so the prefecture dismantles them and replaces the triangles with circles.

There are also other forms

Now you know why sewer manholes are made round. But why they are made so massive and heavy is also an interesting question. Although the explanation lies on the surface.Weight provides relative safety from theft and delivery of the described products to metal collection points. About 10 years ago, a wave of characteristic crimes swept across the country. The covers began to disappear en masse, then the designers came up with an interesting solution.

Most modern sewer wells are not just covered on top with a massive object that one person is not able to carry away. The lids were put on strong hinges, and they turned into real doors, which are additionally locked.

It is impossible to leave the wells open, especially those in which storm sewers and water supply are located. Their depth sometimes reaches 6 meters, and at the bottom of the technical room there are many protruding pipes and pieces of fittings. If a person in the dark falls there, the case will end in death. Therefore, those who are responsible for manholes - and this is the district administration - have a great responsibility for the safe use of this technical structure.

Who else can be responsible for hatches?

But the Russian people are still accustomed to seeing such a hatch

There are wells that are not in municipal ownership, but belong to the property of an apartment building or to the property of a certain legal entity.

All ownerless objects are first registered by the body that registers the right to property. This happens at the request of the local government. Then, through the court, everyone can challenge their own right. If there are no applicants for a year, all ownerless objects are transferred to the departments of specialized companies.

What material is the drain well made of?

There are several popular options for drain wells for summer cottages. Firstly, it is a brick, it is this material that is considered a kind of classic, since it allows you to build a fairly strong, reliable and durable structure. Brick in this case is chosen in much the same way as for construction. That is, it must withstand both high humidity (that is, have a low water absorption coefficient) and low temperatures.

It is necessary to note the features of brickwork in this case. It resembles a chessboard, that is, the bricks are stacked in a checkerboard pattern with a gap of about 50 mm between them. Thus, part of the cells in this "board" will be holes for draining water. To save on such material, you can use a brick that was already in use and left over from the dismantling of some structures.

Secondly, a popular option is a well made of concrete rings. It allows you to relatively inexpensively solve the problem of draining water in the country. Concrete rings are sold ready-made, but they are intended for ordinary wells, and for draining they still have to be finalized by making holes with a grinder.

Thus, any country well should have holes so that water can easily seep into them.

It is generally believed that this is not so important for seasonal living. However, experts recommend not to lose sight of this moment, because this way you can achieve a better result.

Another interesting option is a tire well. In this case, the absorption of sewage can occur only at the bottom. Theoretically, holes can be cut in the walls of tires, but this is rarely done. Despite the fact that such a structure is quite inexpensive, it is not used so often due to numerous shortcomings, which include the settling of solid waste on tire cavities, and relatively low performance.

And finally, another option is a well from a barrel. For it to work well, holes must be made in the walls of the barrel. Only they must be small, otherwise the barrel will begin to rot. Usually drill holes of about 10 mm.The distance between two holes can be 50mm. The disadvantage of this option is a short service life. For him, they usually take a metal barrel, and it will inevitably collapse under the influence of corrosion. The process can be slowed down a bit by using bitumen. Its layer is applied to the surface of the barrel, in the walls of which holes have already been made.

Features of the device of underground communications

We rarely think about how the city sewerage system, drainage systems are arranged, how communication lines and powerful power cables are laid. This is a rather complex engineering system that has its own laws and unshakable rules. When designing a sewerage system, they take into account not only geodetic data, but also a communications system that was laid, perhaps several centuries ago.

The city sewer system project contains a lot of information, which is summarized in one document. This takes into account a number of factors:

It often turns out that one hatch can work both for servicing communication channels and for water supply, heating and sewage systems, which greatly complicates the process of repair and operation.

Generalization on the topic

The round shape of sewer manholes is more practical than all other varieties. Many years of operation of sewer facilities have proven that round holes are more technologically advanced and have a longer service life. And all because such a hatch is more resistant to temperature extremes.

Have you ever wondered why, sewer manholes are everywhere round
and not square? Manhole covers are made of cast iron, it happens that of concrete. This is to ensure that the lid is heavy and cannot open spontaneously. If we talk about cable ducts, then most often there are two shut-off and protective ones. The first weighs much lighter, it is usually made of steel and is needed in order to protect the cable from theft. They place it, just under the protective one, and on the lid itself they simply write the purpose of the hatch.

Why was this form chosen?

Man is a being of a higher order, thanks to his ability and desire to discover the world, to seek and find answers to questions of interest. And people are very curious. Why are giant elephants afraid of mice? Where do the fallen stars go? How to make a magic wand? Why is the manhole cover without corners and extra loops?

Of course, there are squares, stars, triangles on the pavement. But this happens so rarely that it can be classified as an exception. And the pattern is a hatch in the shape of a circle. And there are several reasons for this:

1. The ideal shape for sewer wells is round. They are easier to maintain. The likelihood of clogging is minimal. It is clear that for closing wells it is most rational to use covers of the same shape, but in a slightly increased diameter.

2. The production of round caps is cheaper for factories than the production of other forms. This is mainly due to material savings. What is a circle? This is a pretty good geometric figure. With a limited amount of material, choosing just such a shape will allow you to get the maximum area (compared to other figures). After all, the ratio of the cross-sectional area of \u200b\u200bthe circle to the circumference is greater than that of squares or rectangles.

3. You can also save on thickness if you choose the right hatch shape. The resulting load is evenly distributed, reducing the internal pressure, only in a circle. Therefore, the lid can be thinner, even while maintaining its strength and reliability.

4. The sewer hatch covering the circular well will not fall inside. From no position. And these are additional safety measures for performing plumbing work.

5. Each point on the circumference of the hatch is a point of stress concentration.The uniform distribution of the load, which has already been mentioned above, has another advantage. It is this form that makes it easier to open the well by shifting the heavy cover to the side.

With rectangular hatches, it's a little different. There tension is concentrated in the corners. With such covers you have to tinker.

6. Round options are easier to move, not only because of the distribution of the load, but also simply because of the absence of corners. As a rule, sewer covers are made of cast iron. This is very heavy material. And any product from it is almost unbearable. The circle can be put on edge and rolled.

In addition to the above reasons, one more important point should be mentioned. There is such a production pattern: the less protrusions and corners a part has, the less marriage will come out from under the machine. Therefore, the production of round hatches is more than justified.