Hello always, dear friend!

There is a type of question that is considered to be agility questions. Sometimes this is true. But more often such questions are asked for several purposes at once.Why are hatches round? The interview question is just from this series. Although it is becoming less and less common, because it has already lost its former originality and the effect of surprise.

Let's remember that during an interview they want to evaluate not so much “Who are you?”, but rather “What are you like?”

1. How would you respond to this question? - the first goal of your interlocutor.

He wants to understand your level of emotional maturity.

2. Will you look for the answer to this question? - second goal.

Let's remember that the employer is interested in several questions that he never asks directly. One of them is whether you will solve problems that will inevitably arise in the course of your work.

Either you will look for reasons why the problem cannot be solved, or you will shift the problems onto other people, including your manager.

3. The content of the answer itself - third goal.

Can you solve problems that require intelligence, analytical thinking, and logic?

If instead of answering you say “I don’t know” or “I don’t know”, this means that when faced with a difficult task, you will most likely pass.

How to react?

Let’s immediately agree that we define this question “why are hatches round” as, and not manipulative and not. That's why we respond constructively.

The worst thing you can do is puff out your cheeks and say something like this:

“Listen, what does this have to do with the subject of our meeting?”

After this, consider that you have not passed the test, although in essence you are right. The reason is that you did not accept the rules of the game that are offered to you. I repeat, this question is constructive and is not an attack on your personality. Therefore, it should be answered constructively.

Let's remember the principles of answering constructive questions in an interview:

1. If they ask you questions, that's good. If they don't ask you anything, how will they know that you are the best applicant?
2. As a consequence of point No. 1: Simply give the interlocutor the right to ask any questions. Any question is your opportunity to be better than other candidates. You will answer confidently and calmly, and there is no reason to be afraid or nervous.
3. Majority They are asked to get to know you better, not to hear the correct answer. That's why you came, so that they would know what a wonderful candidate you are.

How to answer?

1. Listen to the end.
2. Verbal reaction - and with the tips of the lips (teeth closed!), a slight nod.
3. A short pause.
4. Answer.

The simplest and most logical answer to this question is:

Round hatch - cannot fall into the well. No matter how hard you try and twist it. The square one has a diagonal longer than its sides, and when lifted, it can slide down into the well. Drowning or even injuring someone. Besides -The diameter of the top of a round hatch is usually larger than the bottom, and it cannot slide in under any circumstances.

In addition, round hatches are more convenient to move - it can be rolled.

A couple more questions from the same series

About the cake

The question itself: How to divide a cake into eight equal pieces using 3 cuts?

Answer: First, you should make a cut crosswise, thereby dividing the cake into 4 equal parts. Next, make one cut horizontally in half along the entire diameter. The pieces turned out lower, but the problem is solved - you have 8 equal pieces.

Second option: after your two cuts we have 4 pieces. We can put them on top of each other. Then cut all four pieces in half using one cut.

About light bulbs

There are three light bulbs in the room. There are three switches in the corridor leading into the room.

Question: How many times do you have to open the door to determine which light bulb corresponds to which switch?

Answer: Opening the door once is enough. We turn on 2 switches at the same time, then turn one off. We enter the room: we see that one lamp is on. It's from the first switch. Place your palm on each of the remaining two bulbs. Which is warm from the second switch, respectively cold from the third.

In the event that no intelligible answer comes to mind, start thinking out loud. Trying to find the right one is much better than a nervous reaction or a “I don’t know” answer. Keep in mind that some of these questions do not have a clear answer at all.

Your attempts to find an answer, a train of thought, and solutions are often more important than the answer itself.

Thank you for your interest in the article. I would appreciate your comment (at the bottom of the page).

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Have a nice day and good mood!

The development of sewer systems in each state took place in its own way. The only common feature in all cities is the need to install hatches. Sewage hatches first appeared in the middle of the 19th century. Then they were made in a variety of shapes - from round to square. In recent years, only round models have been produced. Why?

What is a manhole?

A manhole is a hole in concrete or ground that provides access to underground communications. This hole is always closed with a lid or hatch to avoid accidents. The hatch also has another function - to prevent illegal entry into the underground communications system.

Types of sewer manholes

Lids are divided into types. There are different embossing and patterns on them. For example, on the first sewer manholes they depicted the state emblem and propaganda slogans. Now the covers display the serial number, date and initials of the manufacturer. Sewer people highlight:

• Plastic;
• Iron;
• Rubber;
• Cast iron;

India is considered the leader in the manufacture of sewer manholes.

Why are sewer manholes round?

For many years in a row, only round hatches have been produced. There are several reasons for this:

1. The cost of manufacturing a housing for a round hatch is lower than any other shape (triangular, diamond-shaped, rectangular);
2. Ease of movement. A round hatch is much easier to move: you just need to place it on its edge and roll it in the desired direction;
3. The round hatch is easier to open. For him, any point on the circle is a stress concentration. For example, all lids for jars are also only round;
4. The round hatch will not fall into the sewer system. Any other form has a high probability of subsidence below the established level;
5. The cross-section of the system pipes is round. It would be logical to make the same shape as the lid that covers the sewer system.
6. It is impossible to remove a square (triangular, rectangular) object through a round hatch cover.

In some countries, triangular sewer manholes are used. In Nashua (a city in the USA), underground systems are still covered with triangular-shaped covers. The sharp corners of the triangle indicate to the maintenance crew the direction in which the wastewater flows. However, such hatches were recognized as hazardous to health, and their dismantling began.

The choice of the round shape of sewer covers is dictated by elementary practicality. Such hatches last longer and are resistant to environmental influences. Less material goes into production and they are cheaper. Convenient to work with if you need to get inside the sewer system, safe. The likelihood of a round hatch sagging is very low.

Home comfort

Why are round sewer manholes a necessity or a tradition?

Why are sewer manholes round? What else could they be? Theoretically, the hatch can be square or rectangular. But this design is rather an exception to the rule. A hatch is not a simple hole; it must be securely closed. It must be easy to maintain and safe to use.

If convenience is not an acquired taste, then the round design of the lid can ensure reliability at the level of standard loads. The configuration of the base, which, in fact, is the sewer hatch, depends on its shape.

Waste system

Sewer networks are a set of structures designed to collect and drain wastewater from users to treatment facilities. The easiest way to do this is with the help of underground communications. A trench is dug, pipes are laid in it, through which wastewater will be drained.

In order to be able to service the system over a certain distance, inspection shafts are required. In urban infrastructure with dense buildings, it is possible to install sewer networks only along roads or directly under them. In this case, during heavy traffic, the hatches must be securely closed. But why are sewer manholes round? They must have sufficient strength to withstand the maximum possible transport loads.

In a large city, the number of inspection hatches and various shafts can number in the hundreds of thousands. After all, this is not only a sewer system, it is also a communications network: water supply, heating networks, electricity, gas, telephony, etc.

Manholes

For ease of access to communications, the well shaft is usually made in a round shape. The sewer rings used for the construction of such structures are most often made of reinforced concrete.

The cylindrical shape of the well is most suitable for maintenance. It is more convenient to carry out work in such mines. They are suitable for ventilation, since air circulation in a cylindrical object occurs more intensively.

The size of the cover, base area and internal diameter are selected in accordance with the purpose of the inspection shaft. In this case, all elements of the system will correspond to each other as much as possible. The location, possible loads, and traffic intensity are taken into account.

It depends on the shape of the lid. On the one hand, maintenance personnel must have convenient access to underground communications. On the other hand, the well must be securely closed to prevent foreign objects from getting inside, to ensure the safe movement of pedestrians and vehicles. A round lid is best suited for this, which means the hatch itself should be of this shape.

Depending on their purpose, they are divided according to the type of communications laid under them: engineering cable networks, water supply, gas mains, heating mains, storm and sewerage. The size of the sewer manhole varies from country to country. In Russia, standard dimensions are most often used (645 and 800 mm). Hatches manufactured not in accordance with GOST are designed and developed by manufacturers in accordance with the order and specific technical conditions.

This configuration has a number of advantages. Previously, hatches were made in various shapes. They could be square, rectangular, oval, or even triangular to indicate the direction of water flow. However, the round shape of the lid turned out to be the most suitable.

It will never fall inside the well, no matter how much it is turned. A round lid is easier to open, so the point of application of force anywhere on the circle will be the same. It can be rolled by placing it on its edge. This design is more economical to manufacture.

The round shape of the lid is less susceptible to sagging. It can withstand greater loads with the same thickness, which means it can be made thinner without losing quality. During production, round castings produce a lower percentage of defects (shells, pores, cavities).

Material

The base and manhole covers for critical sewer wells are most often made of cast iron. This material has strength, which makes it possible to withstand heavy loads, and corrosion resistance for a long service life. The weight of the structures is sufficient to prevent passing vehicles from accidentally lifting and moving the cover. Cast iron hatches are made by melting down recycled materials; they are cheaper than their steel counterparts.

In places where there is no heavy traffic, it is not practical to install heavy and powerful structures. Recently, hatches made of plastic, polymers and composite materials have appeared. They are lighter, cheaper, have a sufficient margin of safety, and have a long service life.

In private houses, sewer rings made of reinforced concrete are used to equip sewage systems, inspection wells and septic tanks. In this case, it is quite justified to install the same base for the hatch on top of them. The lid is also made of concrete. It is made of a larger diameter, does not fit into the groove, but simply covers the hatch hole. The massive structure is quite heavy and cannot be accidentally moved. This provides the necessary safety during operation.

Specification and marking

For increased loads on roads, heavy hatches (class T) are used. They can have a weight of over 100 kg and a thickness of over 100 mm. Where vehicular traffic is not provided, lightweight hatches (class L) are used. Structures for gardens, lawns and other areas (class A) have a diameter of 540 mm and a thickness of 50 mm.

Why are sewer manholes round and marked? This is done for the convenience of recognizing their belonging to public utilities. On their covers there are letters: GS - gas network, MG - main gas pipeline, PG - fire hydrant, etc.

Modern public utilities emerged in the world in the 1930s. Despite the variety of shapes, greater preference was given to round lids. Currently, manufacturers of manholes for sewer systems produce exclusively round shapes.

Covers for manholes: weight and maximum load

Despite the fact that modern sewer systems appeared in different countries at different times, the only similarity was the need to install sewer manholes. The urgent need for cast iron hatches arose primarily in large cities with asphalt roads for safety reasons. Still, moving a lid weighing from 45 to 160 kg is many times heavier than the wooden decks and barriers that were used previously.

Note! In recent years, along with cast iron lids, cheaper analogues made of polymer materials have appeared on sale, the minimum weight of which is considered to be 15 kg, the maximum is 48 kg.

Sewer cover shape

The main reason why the manhole cover is round comes from the following considerations.

1. The triangular shape is not suitable based on the structural features of the human body. Otherwise, the size of the hatches would be much larger than modern round ones. And this entails unnecessary hassle in the form of an increase in the necessary raw materials for the production of the lid, therefore, its cost increases.
2. A square-shaped hatch may eventually fall into a well. Moreover, the shape of the well is round. Changing the transitions of sewer manhole shafts to the surface from a round to a square shape is not an easy task; it requires increased financial costs for manufacturing and replacement.

The round shape of the lid has a more than one-sided nuance: such a lid is convenient to carry – i.e. roll, as opposed to square or triangular. But with the increase in the number of thefts in and nearby CIS countries for the sake of profit, the authorities began to look for a way out of the current situation by producing from other materials.

In the United States, lids with grooves or latches are made as “anti-theft” measures. European countries use a combined material for the manufacture of the lid - they combine concrete with cast iron. This helps prevent theft because scrap metal collection centers do not accept hybrid material.

Interesting fact! Enthusiasts are not discouraged, and on the Internet, users are organizing exhibitions of discovered samples with an unusual design with the city added. The art of cast lids dates back about 150 years; every day the global public gallery is replenished with new unusual examples of modern and ancient products.

Modern and ancient manhole covers differ in appearance. If on the old ones you can find engraved coats of arms, various inscriptions and drawings, then modern analogues are designed in a serious style: production number, name of the manufacturing company, date of manufacture. Some organizations request “unique” copies on order, which contain detailed information: the company logo, a short list of services provided, and more.

The main reasons why the manhole cover is round

1. In Russia and neighboring countries, wells and sewer pipes have a circular cross-section. This is the main factor influencing the shape of the lid. In some European and Asian countries, square versions are found. However, these are exceptions to the rule rather than the norm, because in the same Czech Republic or China, where people discovered square-shaped covers, the sections of pipes and wells of the sewer system are also round in shape.
2. Cost reduction. Unlike a round one, the manufacture of a square manhole cover will require 30% more raw materials.
3. Convenience. To install a hatch cover of any other shape will require more costs: incl. human effort and time to install it: the lid will not have to be moved (taking into account the minimum weight of a cast iron specimen of 65 kg, a square one, based on the increase in raw material costs, will be approximately 30% heavier - i.e. about 85 kg).
4. A round-shaped sewer manhole will not fall into the well due to its increased diameter compared to the cross-section of the well.
5. Installation and dismantling of round covers is faster and there are a number of reasons for this:
   no need for more installers to move the hatch;
   the time spent on moving it is reduced - it is easier to roll a round hatch; this method will not work with a square or triangular cover.
6. Load concentration distribution. For a round lid, distribution is carried out over the entire area. Angular lids cannot boast of this - it is the corners that will act as the main load points.
7. It is more difficult to damage the edges of a round hatch than an angular one. During transportation, it can be chipped. Considering that it is the corners that act as the main reference point for distributing the load, a broken piece, regardless of its size, breaks the system and the load is distributed to the remaining corners.
8. Wear resistance. The service life directly depends on the integrity of the manhole cover. If a part breaks off on angular lids, the load is distributed unevenly. Over time, this will cause damage to other supporting corners.

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

The simplest and most logical explanation

A square-shaped lid can easily fall into a hatch, for example, slip through at an angle. This may be because the diagonal of the square is larger than its sides, that is, the lid may fall into the hole. And a circle has the same diameter, no matter how you turn it. And since the diameter of the upper surface of the hatch is always larger than the lower one, the cover will never fall inside the hatch, no matter what position it is in. The round lid is safer than other lid shapes, since it will not fall on the heads of workers who are inside the hatch.

The most frivolous explanation

There is an explanation that, of course, seems funny. The hatches are round because the holes are round. Although, on the other hand, it is easier to dig a round hole than to align the corners of a square or rectangular or triangular hole. And in general, for example, it makes no sense to make a sewer well square, because you will have to spend extra effort and extra time. In addition, round holes are more technologically advanced, they have a longer service life, and are resistant to temperature changes and transformation.

So, there is some truth in this statement too.

The fact is that round hatches are easier to transport. That is, the square cover only needs to be carried, and one person is unlikely to cope with this, because the hatch cover is very heavy. It will take at least two men to carry the manhole cover to the right place. And the round one can be rolled, which is something one adult man can do. Moreover, without experiencing any particular difficulties. Moreover, when closing the hatch with a round lid, there is no need to rotate it, aligning it with the hatch opening. There is some truth in this too; round hatches are much more convenient. Moreover, they are easy to manufacture, because again, you will have to tinker with square hatches; their corners may be damaged during transportation, for example, knocked off.

By the way, the question “Why are hatches round” is asked by recruiters to candidates. They say that the answer to this question allows you to assess the general level of intelligence, how capable it is of solving problems and problems. By asking this question, experts want to see whether the candidate employee has the willingness and ability to enter into discussions and how the candidate solves the task or refuses to solve it. It is also very important how the candidate answers the question, seriously or jokingly. By the way, the world-famous company Microsoft has long used this question when testing specialists who are going to be hired.

To sum it up, it is easiest to say that The lid should be round, including manhole covers!

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