Types of pipelines. The Great Encyclopedia of Oil and Gas

Today, polyethylene pipes are so widely distributed that the diversity of their species is several dozen. They are classified according to several basic criteria: by application, by external diameter, by the permissible bending radius, by operating pressure, and so on.

In the field of application, polyethylene pipes for external water supply networks, gas supply, sewerage, underfloor heating, internal water supply systems and many others are distinguished. According to the working pressure, this material is classified as follows: polyethylene pressureless pipe, pressure and working under vacuum.

Pressure and non-pressure polyethylene pipes

The name "non-pressure" speaks for itself. This type of communication is used for systems whose maximum working pressure does not exceed 0.15 MPa. Previously, pipes of various materials were widely used in non-pressure water supply systems, now, along with metal and asbestos-cement pipes, non-pressure polyethylene pipes were also used, GOST R 50838-2009 allows them to be used even when laying heat supply systems. Such funds are used, mainly, in gravity drainage, drainage, drainage systems.

Pressure polyethylene pipes of low pressure are divided into three types: PE100, PE80, PE63. They are distinguished by the polyethylene brand and the field of application. PE100 and PE80 are recognized as a new generation material, and the range of their application is much wider than that of PE63. They are much stronger, because they can withstand more pressure. They are used in sewage, gas and water supply systems. PE63 is often used to protect a layed electrical cable, a bit less often - in sewer systems.

Characteristics of polyethylene pipes

Thanks to its properties, polyethylene pipes have become so popular. They are much lighter than metal ones, they have good elasticity. To lay these pipes you need a narrow trench, or it will not be needed at all. Easy installation repeatedly accelerates the laying of the entire network. Production, production costs and transportation of such pipes are much cheaper than steel, cast-iron or asbestos-cement pipes.

Polyethylene pipes for water supply do not require any control, are unpretentious in maintenance, easily dismantled. Due to their elasticity they will function reliably even with mechanical overloads.

Plastic pipes have increased thermal insulation properties, are not susceptible to corrosion, and freezing in the water does not affect the properties. With dynamic loads, they are able to restore their shape without permanent deformation. The maximum smoothness of the inner surface and passivity to biochemical environments prevent the accumulation of colonies of microorganisms and the formation of layers, which increases the total operating time of the entire system.

Almost the only drawback of these communications is reduced strength in mechanical compression, and otherwise, they perfectly perform their functions and serve the benefit of humanity.

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Low thermal conductivity, high strength, long service life and reasonable price allow them to be an ideal material for laying a pipeline for various purposes.

Asbestos cement pipes are distinguished by excellent resistance to corrosion, decay, fouling, low thermal conductivity (and thus independence from temperature factors), strength and long service life.

And non-pressure.

In the process, only three components are used for their manufacture: 15% asbestos, 85% cement and water. Asbestos is a fine-grained material of silicate class, which under certain conditions is split into thin and plastic fibers. Thanks to the introduction of this component, the pipes acquire characteristic properties. As for the next component - cement, in most cases Portland cement M500 and above is used in the manufacture.

Scope of asbestos-cement pipes

Asbestos non-pressure pipe

The non-pressure type is manufactured according to the established quality standard and has the following characteristics:

1. The length of the pipe varies from 2950 cm to 5 m.
2. The size of the inner diameter is 50 ... 500 mm.
3. The wall thickness is 9 ... 43.5 mm.

It is used for laying the external pipeline of non-pressure sewerage, where it is not possible to build a pressure sewage system. In this case, the cost of building such a sewage system will be much lower. A good option for observation wells of small depth is the use of sliced ​​asbestos cement rings. The installation of a garbage chute and the installation of a sewage system from this material does not pollute the environment and soil, as it is resistant to the effects of microorganisms. If it is necessary to shut off the pipeline and possibly stagnate waste water for a long period, the risk of soil contamination through asbestos-cement pipes is excluded.

Another option of using a non-pressure type is a shaft or a box for laying telephone communications and electric cables, since they are bad conductors of electricity. Having high electrical resistance, such pipes are not afraid of electrochemical corrosion, arising from the influence of wandering currents.

Polyethylene couplings in non-pressure pipelines connect pipes simply and reliably.

Some types of asbestos-cement pipes and couplings intended for the construction of heating mains for settlements and agricultural complexes can be laid out without channel and even in non-transitory or semi-passages. They are the most economical option for heat transport, because due to their low thermal conductivity, minimal heat losses occur. And as the thermal insulation is used backfilling of the heat pipeline with an affordable and inexpensive hydrophobic gravel with an additional coating film of polymer material.

It has proven itself for the heat, water and drinking systems, which is also suitable for ventilation and chimneys. In the storm sewage system, wide-diameter pipes can be used for the construction of a drainage collector, and products with a smaller size - as drainage drains through crossings and roads.

Asbestos pressure pipe

The discharge view is a straight pipe having a strictly cylindrical shape or a bell-shaped view. It is manufactured according to the following standard sizes:

1. The length is 2950 ... 3950 mm.
2. The thickness of the walls is 7 ... 18 mm.
3. The internal diameter is 50 ... 600 mm.
4. Working pressure 0.3 ... 1.2 MPa.

L - length, D - outer diameter, d - internal diameter, S - wall thickness, I - conditional pass.

The technology for manufacturing this modification can consist of several stages, where it is necessary to maintain the tubes in the steaming chambers to enhance their strength. At the end of this procedure, the strength of the core increases to 70 ... 75% of the initial stage.

Pressure asbestos-cement pipes are distinguished by their durability and the insignificant hydraulic resistance characteristic of this type. They are used for laying a gas pipeline, pressure water pipe, pressure reclamation and irrigation systems. It is also possible to use wells and wells for the arrangement, for durable feeders for livestock, as well as for overlapping of farm buildings. They have been widely used in the construction of pressure sewers, mud pipes and dykes.

When connecting pipes together, threading and welding are not used, but only heat-resistant rubber seals and couplings of the type TM and CAM. Ensuring absolute tightness and at the same time elasticity of joints is due to the resulting effect of self-sealing of the clutch at the pressure of water in the pipeline. Therefore, the advantages of such pipelines include the absence of weak sections in the system - welded joints.

Benefits of use

Asbestos-cement pipes have a number of advantages in comparison with other types of pipes. They are easy to install, have great reliability and high resistance to aggressive environments. In addition, the service life is much longer than that of metal analogues.

Connection of two pressure pipes: 1,2 - asbestos pressure pipe; 3 - asbestos pressure head; 4 - rubber ring type CAM.

Thus, metal pipes, which have low corrosion resistance, require thorough repairs in 5-10 years. Due to corrosion, the inner diameter is narrowed, which is the main cause of low water pressure and low heat rate. Annual pipe blowing does not solve the problem, as rust on the walls does not disappear anywhere and again leads to a decrease in the capacity of the system.

The use of asbestos modification, on the contrary, becomes stronger only with years. Since asbestos in an aqueous medium is not corroded and compacted by hydration of Portland cement. In addition, when the water flow passes, the surface of the pipes is not prone to overgrowth.

Main advantages:

• no waterproofing required;
• when transporting cold water there is no condensation;
• high resistance to aggressive soils and environments;
• not electrically conductive;
• fireproof;
• frost-resistant;
• the maximum operating temperature reaches 160 ° C, the permissible operating pressure can reach up to 1.2 MPa;
• service life 30 ... 35 years.

However, there is an opinion that asbestos-cement pipes are harmful in the transportation of drinking water and are suitable only for sewerage or for other technical needs. The results of numerous studies failed to give an accurate answer, since the presence of asbestos fibers is already present in the water before it enters the tube. And the harm to the body the amount that there is available, it is difficult to inflict. And we will compare it only with the influence on the person of exhaust gases or passive smoking.

The latest scientific data from leading toxicological laboratories in Germany, Switzerland and the USA confirmed that asbestos and its component, chrysotile, are the safest substances among such minerals. Even when ingested, they are easily and quickly removed from it, without having a harmful effect on human health.

Non-pressure pipelines are tested for tightness (tightness) twice: beforehand, before filling; finally, after sending. Pipelines and wells are tested for density not earlier than 24 hours after filling them with water. The test is carried out by sections between adjacent wells.

Non-pressure pipes from viniplast (for example, sewer) can also be made using steel or cast-iron fittings.

Non-pressure pipes, for which a slightly aggressive medium is transported, can be welded together.

Non-pressure pipes are tested for density twice: preliminary test - before backfilling and final - after backfilling.

The non-pressure pipeline is tested with sections between adjacent wells. Testing of pressureless pipelines and pits for density begins no earlier than 24 hours after filling them with water. The hydrostatic pressure in the pipeline during a leak test is created by filling the riser at the top of the pipeline (the ends of the pipeline are drowned with stoppers) or the upper well, if it is to be tested. The hydrostatic pressure should be no less than the depth of the pipes, counting up to the sheath in the upper well of each test section of the pipeline. The pipeline or well is considered to have passed the preliminary test, if there are no visible water leaks during the inspection; while water pumping is allowed.

Pressureless pipelines are tested twice - before filling and after filling the trench. In dry grounds, as well as when the groundwater at the upper well is located at a depth greater than half the distance between the hatch and the top of the pipe, the test is conducted to determine the leakage of water. With a higher location of groundwater, the test is conducted to determine the inflow of water into the pipeline.

Pressureless pipelines from metal pipes are tested in accordance with the instructions for pressure pipelines, the test pressure value being taken to be 5 these.

Acceptance, flushing and chlorination of pipelines

Pneumatic testing of pressure pipelines

Pneumatic tests are permitted for pressure steel and polyethylene pipelines intended for operation under internal working pressure not more than 1.6 MPa, cast-iron, reinforced concrete and asbestos-cement pipes - up to 0.5 MPa.

The compressor and instrumentation are attached to the pipeline section under test (see Figure 6.44, c). Pipelines are considered to have withstood a preliminary test, if there are no defects in joints and welds, integrity of pipelines, as well as shear or deformation of stops. The final pneumatic test is carried out after the backfilling of the trenches, and the steel pipelines with a working pressure of up to 0.5 MPa are tested with a pressure of 0.6 MPa, and with a working pressure of more than 0.5 MPa, pressure equal to 1.15 working. If it is not possible to create the required air pressure in the pipeline, the final test is performed hydraulically. Cast iron, ferro-concrete and asbestos-cement pipelines with a working pressure of up to 0.5 MPa are tested with a pressure of 0.6 MPa, the same pipelines with an operating pressure of more than 0.5 MPa, may only be subjected to a preliminary pneumatic test, and the final test is performed hydraulically. It is considered to have withstood the final pneumatic test pipeline, if its integrity is not destroyed, and the pressure drop during the allotted time does not exceed the permissible value.

The acceptance of the constructed pipelines is carried out by the working and state commissions in accordance with the requirements of the SNiP for the commissioning of completed construction enterprises, buildings and structures. Pipelines with a diameter of more than 300 mm, in addition to strength and density tests, are usually subjected to additional tests to determine their actual throughput.

Before accepting the constructed pipeline, it is pre-washed and then disinfected with chlorine water at an active chlorine concentration of 20-40 mg / l and daily contact. Finally, the pipeline is finally washed to obtain two satisfactory bacteriological and physico-chemical analyzes of water.

Non-gravity gravity pipelines (sewage, stormwater) are tested only for density (tightness), twice: before backfill (preliminary) and after filling (final test). They are tested by filling them with water by sections between adjacent wells, and filled from the upper well, and if the well is not tested, then through the riser, hermetically connected to the pipeline in the upper well. The filled section of the pipeline is kept for 24 hours. The detected defects are eliminated, after which the pipeline is filled with water to the original level and begins the test, i.e. the leakage of water has been measured.

The hydrostatic pressure in the pipeline during the leak test is created by filling the upper well with water (see Figure 6.44, d) or the riser installed in it (see Figure 6.44, d), and the value of this pressure at the top of the pipeline is determined by the excess of the level water in a well or riser above the pipeline sheath or above the groundwater level if the latter is located above the shelter. The hydrostatic pressure should be no less than the depth of the pipe laying, counting up to the sheath in the upper well of each test section. When the pressureless pipelines are pre-tested for density, they are inspected during which the water is pumped into the riser or well to maintain pressure in the pipeline. The pipeline is considered to have withstood a preliminary test, if no visible water leakage is detected during its inspection.

The final testing of pipelines is to determine the leakage of water and compare it with the permissible. The amount of leakage is determined in the upper well by the volume added to the well or riser of water to the initial level, creating the necessary hydrostatic pressure. The test should last at least 30 minutes, and the lowering of the water level in the well or riser is then allowed to be no more than 20 cm. The test for the density of the pipeline and the well with the inflow measurement is carried out by measuring the flow rate of the incoming water in the lower well by a volumetric method or by using a weir . The portion of the non-pressure pipeline that has survived the final density test, if the leakage or water intake does not exceed the values ​​specified in the SNIP.

1. Installation of external water supply and sewage systems / A.K. Pereshivkin, A.A. Aleksandrov, E.D. Bulynin and others; Ed. A.K. Pereshivkin. - Moscow: Stroiizdat, 1988. - 653 p.

2. CHIP 3.05.04-85 * External networks and structures of water supply and sewerage / Gosstroy USSR. - Moscow: TsITP Gosstroy USSR, 1990. - 48 pp.

3. SN 322-74. Guidelines for the production and acceptance of works on construction in cities and industrial enterprises of collector tunnels, constructed by the method of panel penetration / Gosstroy of the USSR. - Moscow: TsITP Gosstroy USSR, 1974. - 37 p.

4. Zaitsev KI, Shmeleva I.A. Guide to welding and installation work in the construction of pipelines. - Moscow: Nedra, 1982. - 223 p.

5. Bykov LI, Karpov V.G. Construction of the linear part of the main pipelines. - Moscow: Nedra, 1977. - 127 p.

6. Kukushkin BM, Kanaev V.Ya. Construction of underwater pipelines. - Moscow: Nedra, 1982. - 176 p.

7. Barishpolov V.F. Construction of external pipelines. M .: Higher School, 1991. - 207 p.

8. Babin L.A. and others. Reference book of master-builder of main pipelines. - Moscow: Nedra, 1986. - 224 p.

Non-pressure is used in the construction and further operation of a gravity drainage system: drainage, drainage, drainage system. Choosing them, you should consider their main characteristics. Non-pressure pipes should have a small roughness of the internal surface. Than it will be less, the less is the risk of plaque formation and layering of the system from within.

Non-pressure concrete pipes are used in drainage, drainage, and sewerage systems ..

Pay special attention to the resistance of pipes to abrasive wear of finished products. The remaining criteria include thermal conductivity, maintainability, the ability to restore molds, as well as rigidity. Virtually no pressure pipes are suitable for any construction.

Since concrete is a universal building material, it is quite logical that it is used in the construction of water pipes and communications that transport liquid. However, unlike ordinary works in construction, in this case, additional components and materials are used.

In general, reinforced concrete pipes are divided by functionality into:

• Ferro-concrete non-pressure pipes. Are intended for erection of pipelines on which gravity liquids are transported. The cross-section of the flows is 5 percent smaller than the cross-section of the pipes themselves.
• Concrete pressure head. Used to build pipelines in which liquids move at significant pressures.
• Concrete nozzles are products that have an extension at one end, and on the other - a special mounting narrowing.
• Pipes without pressure flare. They perfectly cope with corrosion, are very durable, there is a safety of the quality of the surface from within almost throughout the operational period. According to the pipes, the liquid is transported by gravity.

Advantages of such products are: concrete pipes, no matter whether they are reinforced concrete pipes, non-pressure pipes or bell or non-pressure bell fittings, they all have inexpensive cost in installation and production. In general, this is an economical option for the construction of pipelines.

Pipes for structural features are divided into rebated and bell.

The spigots have a cylindrical shape, the surface of the bushing region is stepped. Such pipes can have a sealant, a sole and a special butt joint.

Folded almost no different from the bell, except as a way of docking individual elements. They are sealed with various hermetic means, there may or may not be a sole.

Scheme of joints for seam and socketed pipes: (a - ceramic on rings made of plastisol 1; b - cast iron on rubber rolls with rings 2; in - reinforced concrete on rubber grooved rings 3; d - seaming on round
rubber rings)

Reinforced concrete pipes are the perfect version of concrete elements. They have much greater strength, resistance to compression, deformation, stretching and other processes of destruction. Their service life is measured in tens of years. The design of reinforced concrete pipes differs only in the presence of a "skeleton" in the form of reinforcement made of strong steel. In addition, to enhance the quality of useful properties, these products may have special coatings.

The methods used in the production of reinforced concrete pipes are subdivided into vibro-hydro-pressed and centrifuged.

Reinforced concrete and concrete pipes have very different diameters and, despite their high weight, are very easy to transport. Used in residential communications, engineering networks, road construction.

Form of chrysotile cement couplings for non-pressure pipes: (D - outer diameter of the coupling, d - internal diameter of the coupling, L - length of the coupling, s - wall thickness of the coupling).

The material used in the manufacture is heavy concrete. In non-corrosive pipes, non-aggressive liquids are transported, the temperature of which is not more than 40 degrees, taking into account the pressure reaching twenty atmospheres. In a non-pressure condition, less stringent pressures, but this can vary depending on the

aggressiveness of the environment. Therefore, their usual instillation into the earth to a depth of only up to 6 meters.

Concrete and reinforced concrete pipes are designed for laying non-pressure pipelines underground, which transport non-aggressive, in relation to concrete, aqueous formulations. Depending on the shape of the end, the pipes are divided into smooth and bell-shaped. Smooth tubes are connected together by means of reinforced concrete couplings.

Couplings and pipes must be made of concrete with a mark of at least 300.

The thickness of the walls of couplings and pipes is determined by calculation. Reinforced concrete couplings and pipes are reinforced with longitudinal rods and spirals (the diameter of the rods must be at least 6 mm and the distance between them should not exceed 200 mm, reinforced concrete pipes with a wall thickness of less than 70 mm shall be reinforced with single spirals, from 70 mm and more - with double spirals ).

The thickness of the protective layer should be at least 10 mm. The water absorption of concrete pipes is no more than 8 percent of the weight of concrete, which has been dried to constant weight.

Testing the pipes for water resistance, hydraulic pressure take:

• for pipes with normal strength - 0,5 atm
• for pipes with increased strength - 1.0 atmosphere.

Form of chrysotile-cement non-pressure pipes: (D is the outer diameter of the pipe, d is the internal diameter of the pipe, L is the length of the pipe, and s is the wall thickness)

The definition of the mechanical strength of reinforced concrete pipes is as follows. The pipes selected for testing or cut out of them, not less than 1 meter long, are placed in presses on wooden blocks, which are located on the lower cushions of the presses. On the pipes, along the upper generatrix cylinders, beams are installed. In order to uniformly transfer pressure under the upper beams and on the lower ones, gypsum layers or strips of rubber (sheet) are laid.

Pressure from the press beam is transferred to the pipes through the upper bars at a rate of 500 kg / min per meter of pipe length. The increase in loads is made with interruptions in two minutes.

A lot of work has been devoted to the investigation of the processes of opening and the formation of normal cracks in reinforced concrete elements. According to the method used in practice to calculate the width of crack openings, all are conventionally divided into several groups. There are four.

1. The first group includes methods that are based on Murashov's theory.
2. The methods of the second group are based on semiempirical and empirical dependences, which were obtained as a result of experimental scientific research.
3. The third group includes the Berg technique, where the crack opening width is determined through the reinforcement radius, taking into account the interaction of reinforcement and concrete.
4. The methods of the fourth group include the Thomas hypothesis, where the width of the opening of normal cracks is calculated as the sum of the mutual displacements of concrete and reinforcement in the areas between the cracks.

In the table below, the results of calculating the crack opening width for hazardous sections of reinforced concrete non-pressure pipes are given. Different calculation methods are used here. The pipes were designed from heavy concrete (class B25) and reinforced with a frame in the form of a cylinder, where a wire (class Bp1) with a diameter of 5 mm or a reinforcement with a diameter of 6-8 mm was used as the working (spiral) reinforcement.

The frame made of the reinforcement is made in such a way that the required cross-sectional height is calculated in the tray and tube sheath when calculating (d) and wall thickness (h).

M sd - normative values ​​of bending moments

Msrs - moment of resistance to wall cracks