RU2601013C1 - Polymer pipe and pipeline for fuel transportation - Google Patents

Abstract

FIELD: pipes.

SUBSTANCE: tube has at least one layer containing polyamide. Layer containing polyamide is a barrier layer produced by means of mixture extrusion containing at least one polyolefin and at least one polyamide copolymer with formation of a laminar structure containing multiple layers of polyamide copolymer in the mass of polyolefin. Pipeline includes, at least, two polymer tubes, which can have one or two walls, wherein the connection of single-wall tubes are made by butt welding, and connection of two-walled pipes is made by means of butt welding of barrier pipes and connecting the barrier pipes by means of electro-welded couplings. Polymer pipe and pipeline have high resistance to fuel permeability and high elasticity.

EFFECT: polymer pipe is intended for transportation of fuel, including light oil products and hydrocarbon gases, at fuel and energy complexes and transportation of fuel and gases, as well as at gas filling stations.

25 cl, 12 dwg, 3 tbl

Description

FIELD OF THE INVENTION

The polymer pipe is designed for pressure and suction underground pipelines used for transportation of fuel, including light petroleum products and hydrocarbon gases at the enterprises of the fuel and energy complex, transportation of fuel and gases, as well as at gas stations.

State of the art

When laying underground pipelines for transporting liquid hydrocarbon products and hydrocarbon gases, pipes based on polyolefins are used, containing a barrier layer that prevents the penetration of carbohydrate vapors into soil and air. International standard UL 971 standard "Nonmetallic underground piping for flammable liquids". Underwriters Laboratories Inc, USA, 2006, defines a barrier layer as a layer or layers that reduce or limit permeability.

The barrier layer of the polyolefin pipe can be made of various materials. So, in the application for US patent No. 2015000639, publ. 01/01/2015, IPC F02M 37/00, a pipeline for transporting liquid and gaseous fuels is disclosed, including an inner layer, a barrier layer that prevents diffusion of hydrocarbons, and an outer layer. The inner layer is made of polyethylene, the barrier layer located between the inner and outer layers in the form of a film can be made of a copolymer of ethylene and vinyl alcohol, polyvinylidene fluoride, polyoxymethylene and a copolymer of ethylene and tetrafluoroethylene, and the outer layer can be made of polyamide and / or polypropylene.

A common drawback inherent in pipes containing a barrier layer in the form of a film inside the pipe is the need for additional protection of the barrier layer from mechanical damage and abrasion by introducing an additional protective polymer layer.

Polyolefin-based pipes are also known in the art which comprise a polyamide-based barrier layer made in the form of a film inside a polyolefin pipe.

So, from the patent for utility model of China No. 2729477, publ. 09/28/2005, IPC F16L 47/00, a coextruded composite pipe is known that contains an outer layer based on a polyolefin and an inner layer containing a nanocomposite based on a polyamide and an adhesive layer.

In the patent application of China No. 201764131, publ. 03/16/2011, IPC В32В 1/08, a composite pipe is disclosed consisting of two layers: an outer layer made of high density polyethylene and an inner layer based on polyamide with a thickness of at least 5 mm.

It is known that the use of polyamides as materials for the inner layer of the pipe coming into contact with fuel has a significant drawback, since polyamides contain oligomers that can be “washed out” with the fuel and form salt compounds in tanks, pipelines and tanks. Thus, a common drawback inherent in prior art polyolefin pipes containing a polyamide layer in the form of a film inside the pipe is the need for additional protection of this layer from “washing out” of oligomers. Another common drawback of such pipes is their relatively low elongation, not exceeding 250%, due to the stiffness of the polyamide layer itself and the presence of a binder (adhesive), which is necessary to connect the polyamide-based layer to the polyolefin layer.

As a prototype of the selected pipeline (US patent 6,616,191, publ. 09.09.2003, IPC F16L 11/04), which contains pipes made on the basis of polyethylene and polyamide and designed for gas distribution at low and medium pressure. These pipes consist of polyethylene coated with a layer of polyamide, and if necessary, a binder can be placed between the polyamide and polyethylene. The purpose of applying a layer of polyamide in this case is to facilitate the connection of pipes, for which a sleeve is used, the inner diameter of which is equal to the outer diameter of the pipes to be connected, and glued with a solvent. In one embodiment, the polyethylene pipe may be coated with polyamide inside, in which case the coupler is such that its outer diameter is equal to the inner diameter of the pipes to be connected. You can also simultaneously place a layer of polyamide inside and outside the polyethylene. The claimed pipe can be obtained by co-extrusion.

The disadvantages of the prototype are the need to protect the layer based on polyamide from leaching of oligomers, which contains a layer based on polyamide that comes into contact with the transported fuel, as well as from mechanical damage and abrasion.

A significant drawback of polyolefin pipes containing a polyamide-based layer in the form of a film inside the pipe is the need to use special welded equipment, and in the case of manufacturing double-walled pipes to control fuel leaks, it becomes necessary to use special electric-welded couplings of complex design.

Thus, in the prior art there is a need for polymer pipes devoid of the above disadvantages.

Disclosure of invention

The problem to which the invention is directed is to create a new polymer pipe for pressure and suction underground pipelines used for transporting fuel, including light petroleum products and hydrocarbon gases, which has high barrier properties while maintaining elasticity, the connection of which when laying the pipeline can be carried out by butt welding with a heated tool (NI) and by means of electric-welded couplings (parts with embedded heaters (ZN)) of a simpler design.

The technical result achieved by using the invention is to increase the resistance to permeability of the fuel while achieving high elasticity of the pipes.

An additional technical result achieved by using the invention is the ability to connect the proposed pipes by welding with a heated tool (NI) butt and by means of electric-welded couplings (parts with embedded heaters (ZN)) of a simpler design.

Moreover, a significant advantage of the invention is the possibility of manufacturing pipes as multilayer or single layer.

To solve the problem and achieve the technical result, a polymer pipe is proposed having at least one layer containing polyamide, the difference of which is that the layer containing polyamide is a barrier layer obtained by extrusion of a mixture containing at least one polyolefin and at least one polyamide copolymer with the formation of a laminar structure containing many layers of the polyamide copolymer in the mass of the polyolefin.

When a copolymer of polyamides is introduced into the mass of a polyolefin, a multilayer laminar structure is formed. Many overlapping layers of the polyamide copolymer in the mass of the polyolefin provide the pipeline barrier properties, without affecting the original physical, mechanical and chemical properties of the polyolefin.

In one embodiment of the invention, the polymer pipe is single layer.

In a preferred embodiment, the barrier layer contains not more than 95 wt. % low pressure polyethylene and not less than 5 wt. % copolymer of polyamides.

In one preferred embodiment, the barrier layer contains 85-90 wt. % low pressure polyethylene and 10-15 wt. % copolymer of polyamides.

As the polyamide copolymer in the present invention, a polyamide copolymer or a composition based on a polyamide copolymer can be used, which have the ability to form a laminar structure in the mass of the polyolefin during extrusion.

In one preferred embodiment, the copolymer of polyamides is a copolymer of polyamide-12 and polyamide-6, which is obtained by synthesis of polyamide-12 with the addition of polyamide-6 during the polymerization. The ratio of monomers in the copolymer: polyamide-12 is greater than or equal to 65%, polyamide 6 is less than or equal to 35%.

The formation of laminar layers during the extrusion of a polyolefin and a copolymer of polyamides in this case is due to the fact that polyamide-6 does not melt in the polyolefin due to the higher melting temperature, but forms unmelted flake veins. Polyamide-12, although it does not have adhesion to polyolefins, due to sufficient good melting, it mixes with layers of polyolefin, creating an element of the so-called "hot landing".

An example of a suitable composition may be a DuPont product of the brand Pipelon® UB45.

As low pressure polyethylene, grades suitable for the manufacture of pipes, for example, grades PE 80 and PE 100, can be used.

In another embodiment, the polymer pipe is laminated.

In a preferred embodiment, the polymer pipe comprises at least one polyolefin-based layer and at least one barrier layer containing a polyamide copolymer.

In one preferred embodiment, at least one polyolefin-based layer is made of polyethylene or propylene.

In one preferred embodiment, the polyolefin-based layer is made of low pressure polyethylene.

As low pressure polyethylene, grades suitable for the manufacture of pipes, for example, grades PE 80 and PE 100, can be used.

In a preferred embodiment, the barrier layer contains not more than 95 wt. % low pressure polyethylene and not less than 5 wt. % copolymer of polyamides.

In one preferred embodiment, the barrier layer contains 85-90 wt. % low pressure polyethylene and 10-15 wt. % copolymer of polyamides.

Moreover, as the copolymer of polyamides, as mentioned earlier, can be used as a copolymer of polyamides, and a composition based on it, with the ability to form laminar layers in the mass of the polyolefin.

In one preferred embodiment, the polyamide copolymer is a copolymer of polyamide-12 and polyamide-6.

In one preferred embodiment, the multilayer polymer pipe consists of three layers: an inner layer based on polyethylene, a barrier layer based on a mixture of polyethylene and a copolymer of polyamides and an outer layer based on polyethylene.

The inner layer is designed to provide additional protection against leaching of oligomers contained in the polyamide copolymer, the barrier layer is used to protect oil vapor from penetrating the soil and air, and the outer layer is used to protect the pipe from mechanical damage and UV radiation.

Preferably, the barrier layer contains 85-90 wt. % low pressure polyethylene and 10-15 wt. % copolymer of polyamides.

In one preferred embodiment, the inner and / or outer layers may be made of low pressure polyethylene.

In another preferred embodiment, the inner and / or outer layers may further comprise a colorant.

In another preferred embodiment, the inner layer is made of conductive polyethylene.

The invention also relates to a pipeline comprising at least two polymer pipes according to claims. 1-18 of the claims disclosed above.

In one preferred embodiment, the pipeline is characterized in that the pipes are single-walled.

In one embodiment, the connection of single-walled pipes is performed by butt welding.

In another preferred embodiment, the pipeline is characterized in that the pipes are double-walled, representing a concentrically arranged barrier pipe and a protective pipe, the space between which is made with the possibility of filling with inert gas.

In one embodiment, the pipeline is characterized in that the connection of double-walled pipes is performed by butt welding of barrier pipes and the connection of protective pipes by means of electrically welded couplings.

The inventive pipeline is designed to transport liquid hydrocarbons, such as light petroleum products, such as gasoline and diesel fuel, and hydrocarbon gases, such as methane and its homologues: ethane, propane and butane. Moreover, the inventive pipeline can be used for surface or underground laying and can be both pressure (pressure up to 1.2 5 MPa) and suction (vacuum up to 200 mm Hg).

In one preferred embodiment, the pipeline is for underground installation.

In another preferred embodiment, the pipeline is designed to transport light petroleum products and hydrocarbon gases.

A significant difference of the claimed invention is that the barrier layer is obtained by extrusion of a mixture of a polyolefin with a copolymer of polyamides with the formation of many thin laminar layers of a copolymer of polyamides distributed in the mass of the polyolefin, which helps to increase the barrier properties of the resulting pipe. Thus, the permeability to fuel of the polymer pipe of the invention is not more than 0.2 g / m ² / day. In addition, since the elasticity of polyolefin-based pipes is determined by the high relative elongation of the polyolefin itself, the presence of layers having a lower elongation, such as polyamide-based layers, makes the resulting polymer pipe less elastic and more brittle, which negatively affects operational properties, especially at subzero temperatures. The proposed pipe does not contain layers having a low relative elongation compared to the polyolefin, since the copolymer of polyamides is distributed in the mass of the polyolefin in the form of laminar layers, thereby forming a single structure, which, along with high barrier properties, has higher elasticity compared to the barrier layer made of polyamides in the form of a separate film inside the pipe. The value of the relative elongation of the proposed polymer pipes is at least 300%.

A significant advantage of the invention is the possibility of manufacturing polymer pipes both multilayer and single-layer, while polymer pipes having barrier properties known from the prior art are made only multilayer.

An additional advantage of the claimed invention is the ability to connect the finished polymer pipes with a simpler butt welding method, which can be carried out under conditions common for polyolefin pipes, including at sub-zero temperatures (-15 ° C for gas pipelines, -10 ° C for product pipelines ), while connection methods, including electrofusion welding (welding with embedded heaters (ZN) - up to -5 ° C), gluing, crimping and other connections for pipes containing layers or made of polyamides, polyethylene terephth talat, polyvinylidene fluoride and other similar materials are carried out only at positive temperatures. In addition, polymer pipes are often made double-walled to control leaks. In this case, the use of the claimed invention allows to simplify the connection of pipes due to the fact that the connection of double-walled pipes is performed by butt welding of barrier pipes and the connection of protective pipes by means of electric welded couplings of a simpler design.

Brief Description of the Drawings

In FIG. 1 shows a single layer polyethylene pipe in longitudinal section.

In FIG. 2 shows a single layer polyethylene pipe in cross section.

In FIG. 3 shows an enlarged view B of a longitudinal section of a single-layer polyethylene pipe.

In FIG. 4 shows an extruder screw used to produce laminar layers in a mass of polyolefin.

In FIG. 5 shows a three-layer polyethylene pipe in longitudinal section.

In FIG. 6 shows a three-layer polyethylene pipe in cross section.

In FIG. 7 shows an enlarged view B of a longitudinal section of a three-layer polyethylene pipe.

In FIG. Figure 8 shows the laminar structure of Pipelon ^® UB45 on a cross-section of the wall of a three-layer polyethylene pipe.

In FIG. 9 shows a pipeline including single-layer polyethylene pipes made single-walled.

In FIG. 10 shows a pipeline including single-layer polyethylene pipes made of double-walled.

In FIG. 11 shows a pipeline including three-layer polyethylene pipes made single-walled.

In FIG. 12 shows a pipeline including three-layer polyethylene pipes made of double-walled.

The implementation of the invention

The single layer polyethylene pipe shown in FIG. 1, 2 and 3, has a nominal diameter (D) of 63 mm and a total wall thickness of at least 5.8 mm and consists of a barrier layer 2 containing 85-90 wt. % low pressure polyethylene PE 100 natural color and 10-15 wt. % copolymer of polyamides.

The manufacture of a single-layer pipe is carried out using a single-screw extruder, such as, for example, an extruder KME 125-36 B / R of the German company KraussMaffei Berstorff.

For the manufacture of a single-layer pipe load 85-90 wt. % low-density polyethylene brand PE 100 natural color and 10-15 wt. % copolymer of polyamide-12 and polyamide-6, for example the product Pipelon® UB45. The distribution of heating temperatures over the zones of the extruder is: 190-210-220-230-240 ° C, the rotational speed of the screw of the extruder is 42 rpm.

Moreover, for the manufacture of the barrier layer 2, it is preferable to use a special screw, which ensures uniform mixing of the melts of low pressure polyethylene and the copolymer of polyamides, which contributes to the formation of laminar layers 4 of the copolymer of polyamides in the mass of polyethylene. The construction of a suitable screw is shown in FIG. four.

Depicted in FIG. 4 the screw of the extruder has a length of 1880 mm and consists of the head 8 of the screw, the working part 5 of the screw and the shank 12 of the screw.

The working part 5 of the screw contains turns 6, having a width of 11 turns at the base equal to 6 mm and a radius 7 of the turn equal to 0.5 mm. The distance 13 between the turns is 62 mm.

The screw head 8 also comprises turns 6 having a width of 10 turns in the head equal to 8 mm and a radius 7 of turns equal to 0.5 mm. Moreover, the radius 9 of the head of the screw cone is 9 mm, and the diameter of the base of the screw head is 62.42 mm.

The shank 12 of the screw has a length of 125.24 mm and a diameter equal to 17.98 mm.

The three-layer polyethylene pipe shown in FIG. 5, 6 and 7, has a nominal diameter (D) of 63 mm and a total wall thickness of at least 5.8 mm and consists of:

- the inner layer 1 of PE 100 low-pressure polyethylene with a conductive dye (red color SKP), the layer thickness of 0.4-0.6 mm;

- a barrier layer 2 containing 85-90 wt. % low-density polyethylene brand PE 100 natural color and 10-15 wt. % polyamide copolymer, layer thickness 1.5-2.0 mm;

- outer layer 3 of PE 100 low-pressure polyethylene with black dye, layer thickness 3.2-3.7 mm.

In this case, the inner layer 1, which is in direct contact with the fuel, is intended for additional protection against leaching of oligomers contained in the copolymer of polyamides, or for removing static electricity in the resulting three-layer pipe. The barrier layer 2 is designed to protect against penetration of oil vapor into the soil and air. The outer layer 3 serves to protect the pipe from mechanical damage and ultraviolet radiation.

The manufacture of a three-layer pipe is carried out on an extrusion line consisting of three extruders, such as, for example, a single-screw extruder KME 125-36 B / R of the German company KraussMaffei Berstorff.

For the manufacture of the outer layer 3 in the first extruder load 100 wt. % low-density polyethylene grade PE 100 black (carbon black content of at least 2.0 wt.%). The distribution of heating temperatures in the zones of the first extruder is: 190-210-220-230-240 ° C, the screw speed of the first extruder is 36 rpm.

For the manufacture of the barrier layer 2 in the second extruder load 85-90 wt. % low-density polyethylene brand PE 100 natural color and 10-15 wt. % copolymer of polyamide-12 and polyamide-6, for example the product Pipelon® UB45. The distribution of heating temperatures in the zones of the second extruder is: 180-225-230-235-240 ° C, the rotation speed of the screw of the second extruder is 41 rpm.

For the manufacture of the inner layer 1 in the third extruder load 99 wt. % low pressure polyethylene grade PE 100 and 1 wt. % dye or conductive additives to remove static electricity. The distribution of heating temperatures in the zones of the third extruder is: 185-190-195-205 ° C, the rotational speed of the screw of the third extruder is 85 rpm.

The formation of a three-layer melt containing layers 1, 2, and 3 occurs in a special extrusion line head.

In FIG. 8 shows the laminar structure visible under the microscope that is formed during the manufacture of the barrier layer of the three-layer polyethylene pipe shown in FIG. 5, 6 and 7, containing 85 wt. % low pressure polyethylene grade PE 100 and 15 wt. % additives based on a copolymer of polyamides, brand Pipelon® UB45. A lot of laminar layers 4 of a copolymer of polyamides distributed in the mass of polyethylene provide barrier properties without affecting the initial physical, mechanical and chemical properties of the polyolefin.

To confirm the barrier properties of the resulting barrier layer, permeability tests are carried out for Fuel C reference fuel (standard motor gasoline, toluene / isooctane). For this, pipe samples are made of low pressure polyethylene PE 100 and a mixture of 85-90 wt. % low pressure polyethylene grades 100 and 10-15 wt. % Pipelon® UB45 presented in table 1.

GOST 12020-72 “Plastics. Methods for determining the resistance to the action of chemical media ”involves the assessment of chemical resistance through a change in the physicomechanical properties of the sample after exposure to a given chemical medium for a certain period of time. Since the construction of a three-layer polyethylene pipe requires constant contact with the fuel only with the barrier layer of the inner wall, the only correct way to test for compliance with GOST 12020-72 is also to extract samples with gasoline inside, rather than immersing them in gasoline as a whole.

The calculation of the permeability of the samples is given in table 2. The basis for the calculation is the data on the weight of the samples from 153 to 342 days of the experiment, when all five samples went to a steady state, in which the daily weight loss becomes constant.

The data in table 2 show that for a sample containing 15 wt. % additive Pipelon ^® UB45, there is a minimum permeability to fuel Fuel C (standard motor gasoline, toluene / isooctane).

For elongation tests, samples of type 1 are cut out from pipe samples according to GOST 11262-80.

The data in table 3 confirm that the relative elongation of samples 1 and 2 containing 15 wt. % and 10 wt. % of Pipelon® UB45 additive, respectively, is close to the values for samples made of pure low-pressure polyethylene, which indicates the high elasticity of samples containing a polyamide copolymer.

The resulting polyethylene single-layer and three-layer pipes can be used for the manufacture of pipelines.

So in FIG. 9 shows a pipeline including at least two single-layer polyethylene pipes shown in FIG. 1-3, made single-walled. In this case, the pipes consist of a barrier layer 2, in which a plurality of laminar layers 4 of the polyamide copolymer are evenly distributed. To connect single-layer polyethylene pipes made by single-wall, the butt welding method is used in accordance with GOST Ρ ISO 12176-2-2011 Part 1. Butt welding with a heated tool.

In FIG. 10 shows a pipeline including at least two single-layer polyethylene pipes shown in FIG. 1-3, made double-walled, representing a concentrically arranged barrier tube 14 and a protective tube 16, the space 15 between which is made with the possibility of filling with inert gas. The double-walled pipes were joined by butt welding of the barrier pipes 14 in accordance with GOST 12 ISO 12176-2-2011. Part 1. Butt welding with a heated tool and the connection of the protective tubes 16 by means of an electric-welded coupling 17, the design of which may be different depending on the size, diameter and other characteristics of the manufactured pipes. Connection by means of an electric welded coupling 17 is carried out in accordance with GOST Ρ ISO 12176-2-2011 Part 2. Welding with embedded heaters.

In FIG. 11 shows a pipeline including at least two three-layer polyethylene pipes shown in FIG. 5-7, consisting of an inner layer 1, a barrier layer 2 containing a plurality of laminar layers 4 of a polyamide copolymer, and an outer layer 3 made single-walled. Moreover, the connection of such pipes is carried out by the butt welding method in accordance with GOST Ρ ISO 12176-2-2011. Part 1. Butt welding with a heated tool.

In FIG. 12 shows a pipeline including at least two three-layer polyethylene pipes shown in FIG. 5-7, made double-walled, which are concentrically located barrier tube 14 and the protective tube 16, the space 15 between which is made with the possibility of filling with inert gas. The connection of double-walled pipes is carried out by butt welding of barrier pipes 14 in accordance with GOST Ρ ISO 12176-2-2011. Part 1. Butt welding with a heated tool and the connection of the protective tubes 16 by means of an electric-welded coupling 17, the design of which may be different depending on the size, diameter and other characteristics of the manufactured pipes. Connection by means of an electrically welded coupling 17 is carried out in accordance with GOST Ρ ISO 12176-2-2011. Part 2. Welding with embedded heaters.

An advantage of the present invention is the possibility of using electric welded couplings of a simpler design for connecting polymeric pipes made of double-walled.

Claims (25)

1. A polymer pipe for transporting fuel, having at least one layer containing polyamide, characterized in that the layer containing polyamide is a barrier layer obtained by extrusion of a mixture containing at least one polyolefin and, according to at least one copolymer of polyamides with the formation of a laminar structure containing many layers of a copolymer of polyamides in the mass of the polyolefin. 2. The polymer pipe according to claim 1, characterized in that it is single-layer. 3. The polymer pipe according to claim 2, characterized in that the barrier layer contains not more than 95 wt. % low pressure polyethylene and not less than 5 wt. % copolymer of polyamides. 4. The polymer pipe according to claim 2, characterized in that the barrier layer contains 85-90 wt. % low pressure polyethylene and 10-15 wt. % copolymer of polyamides. 5. The polymer pipe according to paragraphs. 3 or 4, characterized in that the copolymer of polyamides is a copolymer of polyamide-12 and polyamide-6. 6. The polymer pipe according to claim 1, characterized in that it is multilayer. 7. The polymer pipe according to claim 6, characterized in that it contains at least one layer based on a polyolefin and at least one barrier layer containing a copolymer of polyamides. 8. The polymer pipe according to claim 7, characterized in that at least one layer based on a polyolefin is made of polyethylene or polypropylene. 9. The polymer pipe according to claim 7, characterized in that at least one layer based on a polyolefin is made of low pressure polyethylene. 10. The polymer pipe according to claim 7, characterized in that the barrier layer contains not more than 95 wt. % low pressure polyethylene and not less than 5 wt. % copolymer of polyamides. 11. The polymer pipe according to claim 7, characterized in that the barrier layer contains 85-90 wt. % low pressure polyethylene and 10-15 wt. % copolymer of polyamides. 12. The polymer pipe according to paragraphs. 10 or 11, characterized in that the copolymer of polyamides is a copolymer of polyamide-12 and polyamide-6. 13. The polymer pipe according to claim 7, characterized in that the pipe consists of three layers: an inner layer based on polyethylene, a barrier layer based on a mixture of polyethylene and a copolymer of polyamides and an outer layer based on polyethylene. 14. The polymer pipe according to p. 13, characterized in that the barrier layer contains 85-90 wt. % low pressure polyethylene and 10-15 wt. % copolymer of polyamides. 15. The polymer pipe according to claim 13, characterized in that the inner and / or outer layers are made of low pressure polyethylene. 16. The polymer pipe according to claim 13, characterized in that the inner and / or outer layers additionally contain a dye. 17. The polymer pipe according to claim 13, characterized in that the inner layer is made of conductive polyethylene. 18. The polymer pipe according to p. 13, characterized in that the inner layer is in direct contact with the fuel. 19. A pipeline for transporting fuel, characterized in that it includes at least two pipes according to claims. 1-18. 20. The pipeline according to claim 19, characterized in that the pipes are single-walled. 21. The pipeline according to p. 20, characterized in that the pipe connection is made by butt welding. 22. The pipeline according to claim 19, characterized in that the pipes are double-walled, which are concentrically arranged barrier pipe and a protective pipe, the space between which is made with the possibility of filling with inert gas. 23. The pipeline according to p. 22, characterized in that the connection of double-walled pipes is performed by butt welding of barrier pipes and the connection of protective pipes by means of electrically welded couplings. 24. The pipeline according to any one of paragraphs. 19-23, characterized in that it is a pipeline for underground installation. 25. The pipeline according to any one of paragraphs. 19-23, characterized in that it is a pipeline for transporting light petroleum products and hydrocarbon gases.

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