How chimneys are built. Prices for laying pipelines

Main pipelines are pipelines, as well as various branches from the main pipe, the diameter of which can be different (up to a maximum of 1420 millimeters), depending on what they will transport. And of course, the pipes must withstand the pressure under which the substance will be transported, it can be from 1.2 MPa to 10 MPa.

This system can be used for various products, such as: pure oil or its products, electricity, water for heating systems and water supplies, gas, and so on.

The selection of pipes is carried out only after a complete study of the necessary nuances: the traffic intensity of vehicles, their minimum and maximum weight, the composition of the ground soil, climatic conditions, natural obstacles (aboveground and underground waters, irregularities in the earth's surface, and much more).

According to the general classification, main pipelines can be underground, aboveground, underwater. The elevated pipeline is built in special erected structures that will be protected from external factors and damage. And at the same time, there are no inconveniences for transport passing along the highway. For underground pipelines, special trenches are constructed into which pipes are buried. But it is necessary to take into account many factors - the composition of the soil, the depth of the trench or ditch itself, the diameter of the pipes. The bottom of the ditch should be filled with sand or other material. Pipes are covered with several laying balls. But before the underground pipeline is backfilled, it must be checked for cracks or other various damages, which of course will ensure its safety and durability in use.

Preparatory stage

The construction of main pipelines is a very complex and lengthy process. First of all, you need to prepare all the relevant documents. One of the main ones is the pipeline project. It includes a whole range of technical documents (calculations, estimates, drawings of the passage of the pipeline itself and many others that are needed to start construction). This documentation necessarily indicates all the exact characteristics of the pipes (diameter, working pressure, number of stations that will be pumping products).

But in addition to the technical and economic documentation, a project should also be created, which includes all studies of the external environment (environmental factors, study of the soil composition, geographical location and other data). This entire set of documentation must be created without fail for the convenience and complete safety of vehicles, the nearest settlements and the external environment.

The project is the main final document, which indicates not only technical, but also economic calculations. At the same time, taking into account the preservation of the environment and organizational issues for construction, the total cost of the entire pipeline construction.

Building restrictions

During the construction of the main pipeline, there are many restrictions that are specified in many bills, standards and technical requirements. You should be aware that in no case can pipelines be laid in various settlements, on land areas that are engaged in agricultural work, airfields, railway stations, ports, marinas. And also, it is impossible to combine main pipes with electric cables, cables that serve for communication and, of course, with other pipelines. If there is a need to lay a pipeline together with communication cables, then this requires coordination with the Ministry of Communications of the Russian Federation. All distances are specified in the relevant national standards, which must not be violated in any way.

And the deepening of the pipeline fully depends on the working diameter of the pipes that need to be laid. But the main limitations are from 0.8 meters to one meter deep. And as in all rules, there are exceptions - if the territory on which the pipes will be laid is subject to drainage (peat soil, swamps), then the depth of the ditch should be at least 1.1 meters. But in an area where rocks and swamps have superiority, where there is no roadway, the depth of the trench is only 0.6 meters.

The right choice of pipes

The only material from which these pipes must be made is steel. They are classified into three components - without seams, with a straight seam, which are welded by electric welding and pipes with a spiral seam, they can be welded by conventional welding.

For pipes of different diameters, in turn, different types of steel are also used. For example, if the working diameter of the pipe is up to five hundred millimeters, then calm and semi-quiet carbon and low-alloy steels can be used. When the diameter reaches one thousand twenty millimeters, then quiet and semi-quiet low-alloy steels are used. But for a diameter of one thousand four hundred and twenty millimeters - low-alloy steels, thermally or thermomechanically hardened state. The soldered place of the pipes itself must correspond in strength to the base metal. The unevenness of the seam cannot be more than one and a half millimeters per meter of pipe length. Based on this, the total curvature is 0.2 percent of the entire length of the pipe. Factories that manufacture these products have their own standards and produce pipes with a length of 10.5 to 11.6 meters. But before getting into operation, the pipes undergo a mandatory check - "X-ray", which allows you to notice defective places in time and prevent the seam from divergence during the operation of the pipe.

General provisions for the protection of the main pipeline

There are basic rules for the protection of main pipelines, developed by special services. These rules provide appropriate operating conditions for pipelines, the ability to avoid accidents during the transportation of petroleum products, various types of gases.

These provisions are mandatory for compliance with and their implementation by pipeline transport enterprises. Local governments must hold certain documents and, accordingly, provide them to individuals or organizations that want to carry out various activities in the pipeline construction area.

The population, at least once every three months, should receive complete information from the pipeline transport company through local information agencies (print media, radio, local television) about the clear places where the main pipeline passes.

In addition to the general rules for each pipeline, certain regulatory documents must be developed that will ensure the safety of main pipelines.

Objects that match the structure of these rules are classified as objects with increased danger. This is determined by the combination of the pumping process, and the unsafe properties, of the pumped substance itself.

If there is a violation of the pipe structure, then a rupture of steel and even the soil that covers the pipe is possible. The possibility of fire, explosion, which can lead to great destruction around the pipeline, the release of toxic substances into the environment, suffocating smoke, fire and other dangerous factors for people and nature.

Along the entire route where the pipeline passes, there should be special signs, the height of which corresponds to one and a half to two meters from the ground. Such signs should be clearly visible and their order should be every five hundred meters, plus at all corners.

Such boards indicate the name and composition of structures, technical characteristics, the size of the buffer zone, telephone numbers and addresses of emergency services that operate this site. If there is an intersection of a highway and a pipeline, then road signs are installed at such places prohibiting parking of vehicles.

Security zones

In order to avoid various kinds of damage, security zones of main pipelines are established.

They include fenced land plots, twenty-five meters long from the main axis of the pipeline, on each side, in the event that natural gas, oil or refined products are transported. If liquefied gases, unstable gasoline are supplied through the pipes, then the section occupies a hundred meters in length on each side. Even if these plots of land are used for agricultural work or other purposes, work on them does not stop. But on the part of the owners, full compliance with technical rules is required for security purposes.

But it is strictly forbidden to carry out various works that can lead to damage to the integrity of the pipeline and its normal functionality (damage to specialized signs, opening hatches, gates, doors, etc.). Set up garbage dumps in protected areas, dispose of a variety of chemicals.

Without written permission, it is impossible to carry out various kinds of constructions closer than a thousand meters from the axis of the pipeline, as well as to organize mass sports events with the participation of a large number of people, animal pens.

Planting trees and shrubs is prohibited. Build barns for storing feed, fertilizer, hay.

Enterprises that are engaged in pipeline transport are allowed to drive up to the facility only according to the established access schemes. But when emergencies arise, then access is allowed from all sides of the pipeline axis for the timely delivery of the necessary equipment and materials for complete troubleshooting. Subsequently, an accident is drawn up an act in which all material damage is recorded and which is repaid at the expense of the landowner.

When the pipeline passes through restricted areas for general use, then workers serving a particular section of the pipeline receive special certificates that provide them with free passage in this area for technical work.

If necessary, pipeline transport enterprises have the right to cut down trees and shrubs in protected areas, but only with the issuance of tickets that give permission for this procedure.

All work in protected areas can be carried out only upon receipt of a special permit, which is issued after the presentation of all the necessary executive technical documentation, which depicts the existing main pipelines.

Used pipes are suitable for a range of residential, engineering and industrial construction applications. In terms of strength and tightness, they are not inferior to new ones, but at the same time much cheaper. The degree of wear depends on the scope of the original application - what kind of raw material went through the pipeline before dismantling. This is one of the criteria that you should pay attention to if you want to buy a used pipe.

What goals in construction do used pipes solve?

1. Installing a new foundation or restoring an old one.

Piles are made from boo pipes for pile foundations and structures on a reinforcing cage. A pile foundation is needed if the site to be built has mobile soils, a high level of groundwater, or if the construction of a monolith is difficult. The old foundation will become more durable and stable thanks to the "pipe" strengthening.

There are many types of piles. Pipe material is often used for the manufacture of screw piles, which underlie light structures - fences, fences, small outbuildings.

For the construction of bridges (river, sea), bored, bored injection piles are used.

And to create a reinforcing cage, the boo-pipes are cut into rings and metal rods are strengthened with them. Such a frame ensures the strength of the piles and uniform distribution of the load.

2. Development of pits.

So that the dug pit does not crumble and groundwater does not get into it, the soil is strengthened. Used pipes act here in two qualities:

perimeter fence. They are hammered into the soil and form a supporting wall, which prevents the pit from “sliding” and collapsing. Such a fence is called sheet pile;
spacer. It is needed so that the earth does not squeeze out the tongue, it can go in several tiers. Spacer systems are used for deep and complex pits. The design consists of spacers and strapping belts. The latter are made of a channel or an I-beam.

3. Strengthening the coastlines of rivers and seas.

One of the bank protection materials is a metal pipe sheet. It is light in weight, quick to install and does not require pre-digging. This method of bank protection is cheap, the composition of the soil does not affect the installation, and, if necessary, the fence is quickly dismantled.

4. Construction of hydrological structures.

As a sheet piling, bu pipe material is used in the construction of berths, docks and ports. Hydrological structures are found in hydroelectric power plants, dams, pumping stations, shipping locks, etc.

The pipe pile is very durable and absolutely tight, which is important when working with water. It is a protective wall with locks welded to them.

5. Removal of technical water and storm sewerage.

Often, a necessary condition for construction work is to lower the level of groundwater. This is a kind of guarantee that the object will not be damaged by water, will not be flooded. Artificial drainage is required for pits, roads, other underground and surface structures.

Bu pipes provide free flow of industrial liquids and rainwater.

6. Pontoons and other floating structures.

A pontoon is a "raft" made of tubular material. For this purpose, boo pipes that are welded together are suitable. Among the advantages of such buildings are strength, ease of transportation, stability due to the weight and diameter of the pipe material. If necessary, repairs are possible.

The main types of pontoons:

for technical needs;
mooring piers;
boat stations;
floating gazebos;
for rest houses and tourist bases;
floating objects (cafes and restaurants, houses, dachas, baths, etc.).

7. Foundation of lighting poles.

Pipes of the former use are used as a part of the foundation for lighting structures. More often they are used in small load-bearing structures, however, they are also used in power lines (power lines).

To install supports, you need to think over the foundation in advance. The type and dimensions, the bearing capacity of the pipe supports are selected according to the calculations carried out individually in each specific case. In particular, the region of operation is taken into account.

8. Cases for cables, pipes, other utilities.

The case acts as a protective shell. In this sense, used pipes with a diameter of 219 mm and above are suitable. The pipe-case protects against pressure and vibrations, from water and other aggressive media.

A typical technique that is used to lay a pipe-case is called "puncture". To begin with, 2 pits are prepared - outgoing and receiving. Then the used pipe is cut into pieces of 2.5-3 m in length. The resulting “coils” are pushed through the soil one by one into the receiving pit (when the first part is completely immersed in the soil, the next one is welded to its end, etc., until the pipe is completely extended).

The soil is mechanically removed from the case, and then communications, etc. are inserted into it. The space between the outer and inner pipes is poured with concrete.

9. Electrochemical protection of underground pipelines.

Metal pipelines lying in the ground are subject to corrosion. Used pipes are used to protect them and extend their service life. The mechanism of electrochemical protection is based on two principles:

case;
electrochemical reaction of the cathode and anode.

To protect the pipeline from rust, it is necessary to generate a cathodic reaction and eliminate the anodic one. The protected object is the cathode, a negative potential is created on it. And an anode is made from a pipe-case. To close the circuit, the positive pole is connected to the negative. The anode performs the function of grounding, and the corrosion process is suppressed.

10. Design of screw conveyors.

The screw conveyor at the construction site is designed to smoothly supply fine mixtures. The mechanism of the device is simple: a solid screw with wide blades moves in the body-pipe, which move the contents.

A seamless tube is best suited for the auger body. In second place is a pipe with one straight seam or spiral welding. For the construction of screw conveyors, pipes are used from under gas, steam, restored or stale. All of them have a clean, flat surface.

11. Creation of slurry pipelines.

A slurry pipeline is a kind of analogue of a drainage system. Only instead of water, it removes pulp - a mixture of soil, rock and water. Pulp is formed in situations where construction and mining operations are carried out with the use of water or in an aquatic environment. The length of the slurry pipeline can reach several kilometers. From this it becomes clear that boo pipes are a suitable and cheap way to solve this problem.

12. Country construction.

Used pipes solve the problems of private country houses. They are simply connected to each other and can be easily combined with sheet metal. Used pipes are widely used in the construction of fences, frames of wells and wells, chimneys and ventilation ducts. They are successfully used for arches, gates, gates and doors, as frames for garages and sheds.

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1. MT construction methods. Expand one of the methods

The basis for the construction of the main pipeline should be the availability of the following documents:

an approved project (working draft) and a summary estimate of the cost of construction or extracts from them when construction is carried out by several general contractors;

working drawings and approved estimates for working drawings (object and local);

permissions of the relevant departments and operational services for the right to perform construction and installation works;

approved project for the production of works;

2. Composition of general construction works for the construction of the PS and CS.

centering

earthen

Building construction installation

2. Hydraulic and pneumatic test method

The hydraulic test is carried out mainly with water. Natural or artificial reservoirs (rivers, lakes, reservoirs, canals, etc.) are used as its sources. The pipeline is filled with water using filling units through the connection points. Since the presence of air in the cavity of the pipeline can distort the test results, air bleed valves cut into the elevated points of the profile to remove it.

When testing for strength in the pipeline, it is necessary to create a pressure that is 10 ... 25% higher than that with which the pumping will be carried out. First, the pressure in the test area is increased by filling units. When their technical capabilities are exhausted, the filling units are turned off and the pressure testing units are turned on. After reaching the design pressure, they are turned off, the valves are closed and the pipeline is kept under test pressure for 24 hours.

If ruptures occur during pressure rise or holding, the pipes of the damaged section are replaced with new ones, and the test is repeated.

The leak test measures the reduction in operating pressure over a specified period of time. If it is insignificant, then a conclusion is made about the tightness of the tested section of the pipeline. pipeline main construction underground

Hydraulic tests are completed by displacement of water from the cavity of the pipeline. For this purpose, at least two piston-separators are passed on the main gas pipelines at a speed of 3 ... 10 km / h under the pressure of compressed air or gas. Water from oil and oil product pipelines after their testing is removed by one piston-separator, moved under the pressure of the transported product.

Pneumatic testing of pipelines is performed with compressed air or natural gas. Their sources and means of injection are the same as for blowing. The pressure increase in the pipeline is carried out in several stages with a mandatory inspection of the route when a pressure equal to 30% of the test pressure is reached. Then the pressure is raised to the test pressure (1.1 Rrab) and, having closed the shut-off valves, the pipeline is kept for 12 hours. The permissible pressure drop is no more than 1%. Then the pressure is reduced to the operating pressure and maintained for at least 12 hours more. In the event of air leaks or pipe rupture, the air supply is immediately stopped, the pressure is reduced to atmospheric pressure and work is carried out to eliminate defects, after which the test is resumed. At the end of the test, the equipment is dismantled and relocated to a new site.

The advantage of the pneumatic test method is the refusal to use significant amounts of water. In addition, there is no need to displace it at the end of the test. Therefore, it is widely used in testing the strength and tightness of gas pipelines. However, the detection of leaks in pipelines using this method is associated with certain difficulties. So, when compressed, the air heats up. With its subsequent cooling, the pressure in the pipeline decreases, which can be erroneously identified as a leak. On the other hand, air is a compressible medium. Therefore, even in the presence of a small leak, the rate of pressure reduction in the pipeline is small.

The hydraulic method allows fixing even minor leaks: water is a practically incompressible medium and its relatively small leakage leads to a noticeable decrease in pressure in the pipeline. To reduce the amount of water used, it is sequentially moved from one test area to another. However, if the test water cannot be completely displaced, this leads to internal corrosion of the pipelines. In addition, not always along the route there are sufficient volumes of water for testing.

In order to reliably establish the absence of leaks in pipelines in conditions of limited water resources, a combined test method is used, when the pressure in the pipeline is created by two media - air and water or natural gas and water. In this case, the pipeline cavity is first filled with compressed air or gas, and then the pressure is raised to the test pressure by pumping water with pressure testing units.

3. Construction of block-complete NS and KS. The essence of this method. The main elements in the complete-block construction

To ensure high rates of construction of the PS and CS under these conditions, a complete-block construction method is used. The essence of this method lies in the fact that objects are erected from products of a high degree of prefabrication in the form of block-assembly devices (BKU), enlarged assembly units and engineering communications blanks.

In the case of complete-block construction, the following elements are distinguished: block, box, block-box, superblock and block-complete device.

A block is a set of equipment and building structures mounted on a common basis (a gas turbine unit, a pump unit, a transformer unit, etc.). The block must fit into the loading dimensions (Fig. 20.9) - the maximum dimensions of goods transported by rail on a platform or in a gondola car.

Boxing is a transportable building made of lightweight building structures that fits into the loading dimensions.

A block box is a box stuffed with technological equipment and engineering systems, inside which they create a microclimate necessary for long-term work of maintenance personnel and reliable operation of the installed equipment.

The block container differs from the block box in that the access of personnel to the installed equipment is carried out from the outside.

A superblock is a block (or a set of blocks) whose dimensions exceed the loading dimensions.

A block-complete device is an object assembled at a specialized enterprise or an installation site from a set of blocks, boxes, block containers, block boxes, superblocks and interblock communications blanks.

The scheme of organization of prefabricated construction of NS and CS is shown in fig. 20.10

Prior to the installation of block devices, foundations are built for them. In the absence of technological equipment in the block-boxes (operator's rooms, rest rooms, etc.), special foundations are not erected, and the box's support frame is installed on a compacted layer of sand and gravel mixture 10 ... 15 cm thick. In other cases, the choice of the type of foundation depends on the nature of the operation of technological equipment, the presence or absence of dynamic loads.

4. Trenchless method of constructing underground crossings of pipelines

The trenchless method is called because when laying both the casing and the pipeline, they do not arrange an open trench. The technological scheme for performing trenchless laying of crossings includes the following main operations:

Preparatory work;

Laying a casing under the roadbed;

Laying the pipeline inside the casing;

The device of seals, an exhaust candle or a well, a diversion ditch.

The main volume of preparatory earthworks is the arrangement of working and receiving pits. The pits are torn off to a depth somewhat lower than that at which the casing should be laid. The working pit has dimensions that allow you to install all the necessary machines and mechanisms in it and perform work related to laying the casing. The dimensions of the receiving pit must be such that it is possible to carry out the necessary installation work in it to connect additional transition pipes or to make a sealing connection between the casing and the pipe.

The laying of the casing under the road can be performed by various methods: piercing, punching, horizontal drilling and vibro-impact method. In exceptional cases, methods used in mine construction, associated with the use of special mining equipment and technology, may be used.

After laying the casing, a pre-prepared working pipeline is dragged into it. After pulling through, oil seals, exhaust candles are installed, receiving wells are equipped, diverting ditches, and the initial state of roadside structures is completely restored, as well as the landscape of the area. Particular attention should be paid to the latter, since the unrestored relief begins to intensively deform under the influence of rain, wind, and other climatic factors.

5. Accounting for oil. Requirements for oil metering stations

The operating principle of the UUN is based on the direct method of dynamic measurements of the "gross" mass of oil using automatic in-line mass flow converters (hereinafter referred to as mass meters), operating on the principle of measuring the Coriolis force that occurs when oil moves along a pipeline section with a given radius of curvature, in which transverse vibrations. The mass of oil is determined on the basis of the known dependence of the Cariolis force on the oil flow rate and the frequency of transverse oscillations of the measuring section of the pipeline. The "net" weight of oil is defined as the difference between the "gross" weight of oil and the weight of ballast. The ballast mass is determined from the results of measurements of the mass fraction of water, the mass concentration of salts and the mass fraction of mechanical impurities in oil, obtained, including in the laboratory, from a combined sample taken automatically or manually.

Structurally, the UUN consists of the following parts:

Measuring line unit (MIL), consisting of five mass meters, pressure and temperature measuring transducers built into the pipeline, designed to measure the mass flow rate of oil, its temperature and pressure and transmit data to the IMTs-03 measuring and computing complex;

oil quality control unit (OQU), consisting of a sampling device that continuously takes point samples of oil from the pipeline for subsequent laboratory analyzes of oil quality parameters and subsequent manual input of the obtained data into the IMTs-03 IMC, measuring transducers for density, temperature and pressure;

6. Laying the casing under the road by punching

The piercing method is as follows. The frontal part of the casing is equipped with a special pointed tip, the diameter of which is 30-40 mm larger than the outer diameter of the casing. With the help of special jacks installed in the working pit and resting against the back wall of the pit, the tip is pressed into the ground. As the casing is introduced into the ground, it is built up with additional pre-prepared sections. With this method of laying the casing, a very large punching force is required, since when it is introduced into the soil, the soil is compacted with a tip, i.e., it is necessary to overcome the frontal resistance of the soil and the friction force of the outer surface of the casing against the soil.

When laying by piercing, it should be borne in mind that the minimum depth of the pipe should be 3 m, since at a shallower depth the soil surface above the pipe swells, which is completely unacceptable when crossing railways.

The punching method avoids this drawback. The essence of punching is that the casing is pressed into the ground with its open end, and the soil entering the casing is removed.

7. Specify the main elements and nodes of the CS

The main oil pipeline, in general, consists of the following complexes of structures:

supply pipelines;

Head and intermediate oil pumping stations (PS);

Final destination;

Linear buildings.

The supply pipelines connect the oil sources with the main facilities of the OOP.

The main PS is designed to receive oil from the fields, mix or separate them by grade, account for oil and pump it from tanks into the pipeline.

Intermediate PSs serve to replenish the energy expended by the flow to overcome friction forces in order to ensure further oil pumping.

The end point of the main oil pipeline is usually an oil refinery or a large transshipment tank farm.

The linear structures of the main oil pipeline include: 1) the pipeline itself (or the linear part); 2) linear valves; 3) means of protecting the pipeline from corrosion (cathodic and sacrificial protection stations, drainage installations); 4) crossings over natural and artificial obstacles (rivers, roads, etc.); 5) communication lines; 6) power lines; 7) linemen's houses; 8) helipads; 9) dirt roads along the pipeline route.

8. Methods for the production of overhaul of gas and oil pipelines

* all types of work used in current repairs;

* replacement of insulation of gas pipelines, restoration of the pipe wall with the replacement of insulation, patching, cutting and inserting a new coil, replacement of individual sections of pipes.

* repair of masonry of wells with dismantling and replacement of ceilings, repair of waterproofing and plastering of wells, change of stairs and running brackets, increasing the height of wells;

* removal of individual sections of gas pipelines on the facades of buildings;

* disassembly of valves and replacement of worn parts, scraping, boring or replacement of sealing rings, lubrication;

* replacement of worn valves;

* dismantling or replacement of condensate collectors and water seals, repair and replacement of carpets;

* replacement of supports of above-ground gas pipelines;

* laying of separate sections of gas pipelines

9. Works performed during the preparatory stage of the construction of the PS and CS

1. Arrangement of the construction site, access roads

2. Construction of temporary premises for accommodation and consumer services for workers, as well as for accommodation of arriving equipment and materials

3. Delivery to the construction site fuel

10. Classification and methods for reducing oil losses during pipeline transport

Technological losses of oil (petroleum products) during pipeline transportation and transshipment may occur when:

Collection and disposal of leaks through stuffing box and end seals of shafts of centrifugal pumps;

Injection and pumping out from tanks of pumping stations, transshipment tank farms and filling points of main pipelines

Accidents, leaks, dug TP

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PVC

In Western countries, pipes made of polyvinyl chloride appeared in the mid-thirties of the twentieth century. They have been used for a long time for arranging a cold water supply network in individual construction. At the moment, this type of construction is practically not used in European countries (over time, PVC begins to release toxins during operation), the only exception being sewage systems.

In our country, PVC pipes are used as underground water and sewer networks outside buildings. In multi-storey construction, PVC pipes are not used, as they are not suitable due to the organic diameter. In addition to all this, PVC structures are short-lived, and the most vulnerable places are at the joints (the installation of this type of pipe is done using glue fittings).

As for PVC pipe segments, they are among the most low-capacity ones. These products are supplied to the market mainly by Polish manufacturers, such as Crap-linnski, Kaczmarek, Armakan, including the Brovarsky Plastics Plant and others.

Polyethylene

One of the main advantages of polyethylene pipes is their resistance to low temperatures (up to -20 degrees Celsius), which, in turn, allows you to lay engineering networks in the winter and operate them in rather harsh climatic conditions. As a rule, polyethylene pipes are used mainly for cold water supply, since when exposed to high temperatures, the strength of this material decreases, and it softens to some extent. It is not recommended to use polyethylene pipes in open networks, because under the influence of direct sunlight they quickly age. To stabilize the material, the developers began to add carbon black to the polymer.

There are also pipes made of cross-linked polyethylene. Such a material is much stronger than conventional, and in addition, it is even more resistant to high temperatures. Pipes of this type are widely used for hot water supply, as well as in heating systems (pipes equipped with an “oxygen-blocking layer”). The material that is used for the manufacture of polyethylene cross-linked pipes is cross-linked by several methods: peroxides, ionizing radiation, organosilicon substances. Polyethylene pipes are connected mechanically by means of propylene and brass fittings.

metal-plastic

Metal-polymer pipes are a fairly reliable building product, which consists of five layers, namely: the main pipe is made of cross-linked polyethylene, an adhesive layer applied to the outer surface, a layer of aluminum foil, the thickness of which is 0.1-0.15 millimeters, another adhesive layer, outer protective sheath made of polyethylene. Metal-polymer pipes are made by extrusion: that is, the aluminum tape is butt-welded by means of ultrasound and coated on both sides with glue and layers of polyethylene.

Pipes of this type have a low coefficient of linear expansion and are well protected from oxidation. Metal-polymer pipes can be bent in the right direction without fear of rupture. Such pipes tend to retain the shape given to them, this is one of the reasons that they are used in the installation of complex system and piping configurations.

The most effective use of pipes of this type is in an open connection, for example, they are used to connect water heaters, radiators, etc. But due to the fact that their diameter is not large - up to 40 millimeters, their scope is narrowed.

Polypropylene

Among plastic pipes, propylene pipes have the greatest strength and durability at high temperatures. Unlike polyethylene pipes, propylene pipes are more rigid, and their structures are assembled using fittings: tees, angles, etc.

The installation of a polypropylene pipeline takes place under the influence of a temperature of +260 degrees Celsius - this, in turn, provides a fairly strong homogeneous (welded) connection, the most reliable of all methods that exist. The welding process itself is quite simple: cut, heat, join.

metal pipes

There are several types of metal pipes depending on their area of application, namely:
Electro-welded galvanized and black pipes are used as the main elements of plumbing, heating and gas systems, including in the manufacture of metal structures.

Galvanized pipes are endowed with additional anti-corrosion protection. Seamless pipes are widely used in drilling, installation of oil and gas pipelines, heating networks, and in machine-building production. Water and gas pipelines (black and galvanized) are used in heating systems, water supply and gas supply.

Galvanized pipes are not subject to rust formation inside the system; profile pipes of this type are used in the production of metal structures, they have both a rectangular section and a square one.

Classification of metal pipes by production method:

welded steel pipes - are made by bending a sheet of steel and making a weld: longitudinal or spiral;
cast steel pipes - pipes of this type are produced at specialized turbo-casting plants;
seamless pipes - are made by means of a solid billet by forging or pressing.

Classification of pipes according to the conditions of use

Depending on the purpose for which pipes are used, they are divided into - pipes for special (purpose) purposes and pipes for general purposes. Special purpose pipes are also classified according to such additional features:

steel pipes, designed for use in heating networks, in gas and water pipelines;
high-strength pipes for drilling rigs - casing and drilling;
pipelines for transportation of oil and gas under high pressure;
boiler pipes, endowed with the property of increased heat resistance;
pipes intended for use in chemical industries have high corrosion resistance;
steel pipes with a rectangular profile - are widely used in mechanical engineering and construction (manufacturing of various types of equipment and attachments for machines);
bearing tubes - mainly used in the production of roller and ball bearings.

Classification of metal pipes according to the method of protection against corrosion
The corrosive process is the main enemy during the operation of metal pipes. The corrosion process can occur both on the outside of the thai and on the inside of the pipes. Protecting pipes from the corrosion process can increase the cost of their production. For example, steel pipes made of stainless steel are mainly used in the chemical and food industries.

As a corrosion control method, galvanizing is used, that is, pipes that undergo this process have a thin layer of metal resistant to oxidation and chemical reactions on their surface. Using this method, the cost of such pipes will be, to some extent, more than pipes made of stainless steel.

Steel pipes coated with a polyethylene anti-corrosion layer will last several decades longer than pipes without any protection.

When purchasing steel pipes, it is necessary to pay special attention to the manufacturer. Pipes manufactured by the domestic industry are of high quality, which is recognized throughout the world. But over the past few years, metal pipes from China have begun to appear on the market, which are sold at dumping prices. Deciding to purchase this product, you should weigh the pros and cons well. Since saving on such materials can result in big losses.

In this case, you can also classify pipes by manufacturer, that is:

metal pipes of a domestic manufacturer - high quality and high price;
Chinese-made metal pipes - mediocre quality and dumping prices.

One of the moments of the construction of the building is the laying of heating networks in it.

The heat network must meet the following basic requirements:

a) ensure the supply of specified quantities of water to the places of its consumption under the required pressure,

b) have a sufficient degree of reliability and uninterrupted supply of water to consumers.

In addition, fulfilling the set requirements, the network must be designed in the most economical way, that is, to ensure the lowest value of the reduced costs for the construction and operation of both the network itself and other structures of the system that are inextricably linked with it in the operation.

The fulfillment of these requirements is achieved by the correct choice of the configuration of the network and the material of the pipes, as well as the correct determination of the diameters of the pipes from a technical and economic point of view.

Currently, in the city of Khabarovsk, mainly steel pipes are used in heat supply systems. Basically, steel pipes are used for water conduits operating at significant internal pressures, as well as for water lines when they are laid in macroporous soils, seismic regions, that is, in conditions where good pipe resistance to dynamic loads and bending forces is required.

Steel pipes are produced without coatings on the outer and inner surfaces of their walls with any composition that protects the metal from corrosion. Therefore, the insulation of steel pipes laid in the ground must be carried out during their laying. Corrosion of metal pipes, especially steel pipes, leads to a huge waste of metal, reduces the life of water lines, causes accidents and water leaks, increases the roughness of the inner surface of the pipe walls and, consequently, pressure loss in them, which is associated with additional supply costs. water. Thus, pipe corrosion causes an increase in both construction and operating costs in the water supply system.

The use of synthetic materials (plastics) for the manufacture of pipes for various purposes (and in particular for water supply) has recently become widespread in world practice. Plastic pipes are currently being manufactured:

a) high density polyethylene

b) low density polyethylene,

c) from vinyl plastic.

The advantages of plastic pipes include their high corrosion resistance (and hence durability), low weight, dielectricity, wall smoothness (and hence low hydraulic resistance), low thermal conductivity and ease of machining (cutting, drilling, etc.). Due to the low roughness of the inner surface of PVC products, the friction between the flowing liquid and the walls is insignificant, the pressure loss is 30 percent less than in metal ones. Therefore, the use of PVC pipes is more beneficial in water supply than the use of steel pipes. A positive property of polyvinyl chloride is its reduced flammability and increased chemical resistance in comparison with other polymers. It is also less sensitive to UV radiation. Compared to polyethylene pipes, PVC pipes have higher performance characteristics. PVC has the lowest coefficient of linear thermal expansion compared to other polymers used: for comparison, it is 2 times lower than that of polypropylene. PVC pipes can be in operation without chemical and mechanical changes for 50 years or more. The results of 30 years of tests of continuous operation of pipeline systems show that the period of reliable operation of systems can exceed 100 years. Among its advantages is fire safety due to high ignition temperature (+440 °C) and oxygen index (necessary to maintain the combustion process with the level of oxygen) - 60%. For polypropylene, for example, it is only 17, and for polybutene - 18%.

The disadvantage of CPVC pipes is increased rigidity.

Since its inception in 1960, 600 million linear meters have been installed. m of pipes from this material. Determine the need for the company to replace pipes for the next five years.

According to the company's reporting, on average, it is necessary to install 23,370 linear meters of heat-conducting pipes on PVC pipes during the year.

Using the data of the quarterly directory RegioStroyInform No. 4.200, the cost of seamless metal pipes is 140 rubles per linear meter. We will make a calculation for the replacement of pipes according to the same reference book.

Table 3.2 - Calculation of the replacement of seamless, metal pipes d 159 * 6 per 1 m p

Let's calculate the installation costs of 23370 linear meters:

217 rubles / m * 23370 m = 5071290 rubles.

Since the service life of steel pipes is 20 years, and the service life of PVC pipes is 50 years, we would replace steel pipes 2.5 times in a period of 50 years. Since the service life of the pipes is different, in order to come to comparable data, we will increase the costs by 2.5 times.

5071290 rub. ? 2.5 \u003d 12678225 rubles.

We will make a calculation for the replacement of PVC pipes. According to the reference data of the reference book RegioStroyInform No. 4.200, the cost of one linear meter of pipe is 206 rubles.

Table 3.3 - Calculation for the replacement of PVC pipes d 159? 6

Let's calculate the cost of replacing 23,370 linear meters of PVC pipes with a service life of 50 years:

292 rubles / m * 23370 m = 6824040 rubles.

The economic effect in monetary terms will be:

12678225 - 6824040 = 5854185 rubles.

In the design process, a feasibility study is often carried out to compare options for water supply facilities in order to choose the most economical option. The main criteria for economic comparison of options are the construction cost (capital cost) of the system or structure and the annual operating cost (operating cost).

We know the building cost. In the first case (steel pipes), it is:

K 1 \u003d 5071290 rubles. * 2.5 \u003d 12678225 rubles.

In the second case (PVC pipes), the construction cost is:

K 2 \u003d 6824040 rubles.

We calculate the operating cost in table 3.15. Under the operating cost, we mean the cost of replacing pipes and their operation during their service life.

Table 3.4 - Calculation of the operating cost of pipe replacement options

Savings on the operation of PVC pipes per 1 linear meter per year is 2.2 rubles.

The operating cost is equal in the first case (taking into account the shorter service life for steel pipes):

S 1 \u003d 38.8 * 2.5 \u003d 97 rubles.

In the second option, S 2 \u003d 41 rubles.

Let's compare the costs for each of the options, which are the sums of the construction cost and operating costs for T years, T=50 years.

K 1+ TS 1 \u003d 12678225 + 50 * 97 * 23370 m \u003d 126022725 rubles.

K 2 +TS 2 \u003d 6824040 + 50 * 41 * 23370 m \u003d 54732540 rubles.

When comparing cost options in the second case, it is less by 71290185 rubles. calculated for 50 years or 1425803.7 rubles. per year, so the second option (the use of PVC pipes) is more profitable. Based on 1 linear meter, the annual cost reduction for the construction and operation of the pipeline when using PVC pipes compared to steel pipes will be 61.01 rubles.

As an assessment of the result of the implementation of this project, we consider its economic effect and economic efficiency.

The economic effect is an absolute indicator (profit, sales income, etc.) that characterizes the result of the enterprise. The main indicator characterizing the economic effect of the activities of a manufacturing enterprise is profit. The net economic effect is the profit minus the cost of obtaining it. /35/

Efficiency, in contrast to the effect, takes into account not only the result of the activity (forecast, planned, achieved, desired), but considers the conditions under which it is achieved.

Economic efficiency is a relative indicator that measures the effect obtained with the costs that caused this effect, or with the resources used to achieve this effect.

Efficiency is determined by the ratio of the result (effect) and the costs that cause this result.

With the introduction of this option during the first year of operation of PVC pipes, the economic effect per year in monetary terms will be 4,828,000 rubles.

The economic efficiency in this case will be

EF \u003d (14900200 rubles - 12775500 rubles)? 14900200 rub. = 0.143? fourteen%.

That is, already during the first year of the project, the net profit will cover the costs of the project by half.

This level of efficiency for the project can be considered very high. In addition, here we did not take into account the savings from reducing heat losses during its transfer from the producer to consumers. Therefore, we can say that in addition to the economic effect in monetary terms, there will also be a social effect, since the consumer will receive the heat he paid for in full.

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