RU2665776C1 - Polymeric reinforced pipe with electric heat tracing - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the oil and gas industry and can be used to collect and transport oil, water, gas, chemical reagents through pipelines based on long-length flexible polymer reinforced pipes. Polymer reinforced pipe consists of an inner polymeric layer constituting the base of the pipe, to the outer surface of which the following is applied: a reinforcing layer, an intermediate polymeric shell, a coil of insulated conductors having an additional outer shell in the form of a ring sector bounded by the inner and outer radius of the conductor arrangement, and an outer polymeric shell, the reinforcing layer being made of coils of metallic or polymeric tapes, polymer filaments or metal wires.

EFFECT: technical result of the invention is the reduction of heat losses to the environment and prevention of freezing of the fluid transported through the pipe at negative temperatures with high strength characteristics.

5 cl, 4 dwg

Description

FIELD OF TECHNOLOGY

The invention relates to the oil and gas industry and can be used to collect and transport oil, water, gas, chemicals through pipelines based on long flexible polymer reinforced pipes.

BACKGROUND

A known design of a flexible reinforced pipe, which has an outer layer and one inner layer made of polymer material, between which is located at least one reinforcing layer made of steel tape coated on at least one side with an adhesive (RU 151014 U1, publ. 09/29/2014).

The disadvantages of the design of this pipe can be considered the use of only steel tape as the reinforcing layer and a very small ratio of the thickness of the steel tape to the inner diameter of the pipe, which is 0.0006-0.002.

Known pipeline disclosed in RU 147579 U1, publ. 02/21/2013, with an electric heating system, comprising a umbilical consisting of a working pipe, along the entire length of which a heating element is installed, enclosed in an outer shell. A high-resistance conductor wound around a working pipe is used as a heating element, and two non-intersecting insulated low-resistance conductors are also wound around a working pipe over a high-resistance conductor, while the step of winding a high-resistance conductor is much larger than the step of winding a low-resistance conductor, the first and second low-resistance conductors are alternately electrically connected to high-resistance conductor in individual places of their crossing, during the winding of spaced apart from each other at different distances. The pipe has a heat-insulating layer located between the heating element and the outer shell.

The disadvantage of this utility model is the extremely complex switching system of low-resistance and high-resistance conductors, mutual crossing of conductors, different distances between conductors during winding.

Known multilayer pipe disclosed in RU 120183 U1, publ. 05/18/2012, including an internal polymer pipe, reinforcing a system of high-strength threads, which can be combined into groups forming ribbons.

The considered PM has good weight characteristics and heat-insulating properties due to reinforcing of the base pipe with polymer threads or tapes, but does not contain a heating system for the transported fluid, which limits the use of this multilayer pipe in winter conditions.

Known patent application RU 2014/137407, publ. 04/19/2013, comprising a heated liquid pipe containing an inner tube, an outer braid, and a heating element located between the inner tube and the outer braid, the heating element comprising an inner core made of a first metal material and an outer casing made of a second metal material.

Despite the presence of built-in heating elements, the pipeline has limitations on mechanical strength, as the heating elements are located under the outer braid and with significant internal pressure in the pipe, it is the reinforcing elements that must absorb all the radial mechanical load that arises, which will reduce the reliability of the entire pipe structure as a whole.

The invention is known [RU2315223 of 04/13/2006], including a flexible, load-bearing, polymer pipe, the walls of which are made of a continuous layer of polymer material, inside of which longitudinal and transverse reinforcing elements are placed in the form of metal wires or tapes or high-strength chemical fibers.

In the present invention there are no heat-insulating layers and an integrated system for electric heating of the load-carrying pipe.

In addition, the prior art flexible reinforced pipe disclosed in RU 165000, publ. 10/12/2015, a prototype having an inner and outer layers made of a polymeric material, between which there is a reinforcing layer of metal tapes spirally wound with 4 coils, the first two coils of metal bands having the same direction, and the subsequent coils having the opposite direction, moreover, the angle of the coils of metal tapes relative to the axis of the pipe has a value of 55 ± 5 °, and between the metal tapes of one coils there is a gap of 5 to 15% of the width of the tape, the thickness of which is 0.3-1.5 mm.

The prototype under consideration has the following disadvantages:

- the use as a reinforcing layer of only metal tapes reduces the operational characteristics of the pipe in terms of weight characteristics and thermal conductivity;

- despite the fact that the thermal conductivity of the pipe under consideration due to the polymer layers is lower than that of metal pipes, however, the pipes in question will be inferior in this indicator to metal pipes with a heat insulating coating;

 - At present, metal thermally insulated pipes with built-in electrical heating systems are intensively used, which is absent in the considered pipe design.

SUMMARY OF THE INVENTION

The objective of the claimed utility model is the design of a flexible high-pressure polymer reinforced pipe with high performance properties, such as increased thermal insulation, built-in electrical heating system.

The technical result of the invention is to reduce heat loss to the environment and to prevent freezing of the fluid transported through the pipe at low temperatures, as well as reducing the installation time of the pipeline and the cost of maintaining the pipeline during its operation, increasing the life of the pipeline.

The specified technical result is achieved due to the fact that the polymer reinforced pipe contains an inner polymer layer constituting the base of the pipe, on the outer surface of which a reinforcing layer, an intermediate shell, is sequentially applied, twisted from insulated conductors having an additional outer shell in the form of a ring sector bounded by an inner and the outer radius of the laying of conductors, and the outer polymer shell. In this case, the reinforcing layer is made of at least two coils of metal wires or threads or metal or polymer reinforcing tapes.

A polymer sheath is applied between the reinforcing layer and the midwire of insulated conductors.

A heat-insulating layer can be applied between a coil of insulated conductors and the outer polymer sheath.

Under the outer polymer sheath, a twist of metal tape can be applied.

In a wound of insulated conductors, single insulated conductors are located, as well as conductors in the form of twisted pairs or optical modules.

At least one coil of metal reinforcing tapes, polymer reinforcing tapes, threads or metal wires has the opposite direction of winding.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more clear from the description, which is not restrictive and given with reference to the accompanying drawings, which depict:

FIG. 1 - high-pressure flexible polymer reinforced pipe (option 1).

FIG. 2 - high-pressure flexible polymer reinforced pipe (option 2).

FIG. 3 - high-pressure flexible polymer reinforced pipe (option 3).

FIG. 4 - a fragment of a midwife from insulated conductors.

1 - inner polymer layer; 2 - the first winding of reinforcing tapes; 3 - the second winding of reinforcing tapes; 4 - the third winding of reinforcing tapes; 5 - the fourth winding of reinforcing tapes; 6 - intermediate polymer shell; 7 - winding from insulated conductors; 8 - heat insulating layer; 9 - twisting from a metal tape; 10 - outer polymer shell; 11 - the first twist of reinforcing wires or threads; 12 - the second twist of reinforcing wires or threads; 13 - conductor; 14 - an insulating layer of a conductor; 15 - outer shell of the conductor; 16 - inner radius of laying conductors; 17 - the outer radius of the laying of conductors; 18 - ledges; 19 - twisted pair; 20 - optical modules; 21 - placeholders.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the first embodiment of the invention (Fig. 1), the reinforced polymer pipe comprises an inner polymer layer (1) constituting the base of the pipe, on the outer surface of which a reinforcing layer is sequentially applied, of four sequentially spirally wound coils (2-5) of reinforcing polymer or metal tapes, an intermediate shell (6), twisting (7) of insulated conductors and an outer polymer shell (10). In addition, an intermediate polymer shell (6) is applied between the reinforcing layer and the coil (7) from insulated conductors (13) in the form of a continuous polymer layer, the thickness of which is approximately 5% of the outer diameter of the pipe and is determined by the geometric correspondence between the individual structural elements.

In addition, a heat-insulating layer (8) with a thickness of 5 to 15 mm and determined by the required heat-insulating properties can be applied between the coil (7) from insulated conductors and the outer polymer shell (10).

Additionally, under the outer polymer shell (10), a coil of metal tape (9) 0.2-0.6 mm thick can be laid, which can be applied to a heat-insulating layer (8), or to a coil (7) of insulated conductors in the absence of in the design of the claimed pipe of the insulating layer (8).

In accordance with the claimed invention, the design of the claimed reinforced polymer pipe may have various coatings.

In FIG. 2 (option 2) shows a high-pressure polymer reinforced pipe, consisting of an inner polymer layer (1) that forms the basis of the pipe, the first winding of reinforcing tapes (2), and the second winding of reinforcing tapes (3), and the directions of the windings have the opposite direction, over the reinforcing windings The tapes are coated with an intermediate polymer shell (6), over which a coil (7) of insulated conductors, a heat-insulating layer (8) and an outer shell 10 are applied.

In FIG. 3 (option 3) shows a high-pressure polymer reinforced pipe, consisting of an inner polymer layer (1) that forms the basis of the pipe, the first winding of reinforcing threads or wires (11), the second winding of reinforcing threads or wires (12), while the windings have the opposite direction , an intermediate polymer shell (6) is laid over the coils of reinforcing yarns, over which a coils (7) of insulated conductors are superimposed, twisted of a metal tape (9) having an outer shell (10).

In FIG. 4 shows a fragment of a midwire (7) of insulated conductors. Each elementary conductor (13) of a round or rectangular shape has an insulating layer (14). The conductors may have an outer shell (15) in the form of a sector of the ring bounded by the inner (16) and outer (17) radii of the laying of conductors. Sector conductors, in turn, may have mutually complementary protrusions (18) at the edges for mutual engagement. If necessary, twisted-pair conductors (19), optical modules (20), or simply fillers (21) can be placed in a wound of insulated conductors. In this case, a coil (7) of insulated conductors has a thickness determined by the reliable insulating properties and dimensions of the conductor. For example, for a conductor with a diameter of 1 mm, the generally accepted insulation thickness will be 0.8 mm and the shell thickness about 0.7 mm. Thus, the total thickness of the layer of insulated conductors will be 1 + 2 * 0.8 + 2 * 0.7 = 4.0 mm. The width of the insulated conductors is chosen so that their coil is as dense as possible without gaps, and is determined by the circumference of the coil divided by the number of conductors in the coil.

In the claimed invention can be applied at least two coils of polymer threads or metal wires or at least two coils of metal or polymer reinforcing tapes. At least one coil of metal reinforcing tapes, polymer reinforcing tapes, polymer filaments or metal wires has the opposite direction of winding.

In the claimed high-pressure polymer reinforced pipe, the inner layer (1) constituting the base of the pipe, the intermediate polymer shell (6) and the outer polymer shell (10) are made of a corrosion-resistant polymer material selected from the group: polyethylene, polyamide, ultra-high molecular weight polyethylene, polyvinyl chloride.

As a heat-insulating layer (8), materials with low thermal conductivity, such as foamed polyethylene and polyvinyl chloride, are used.

As reinforcing polymer tapes, a polymer material selected from the group: polyester, polyolefins, ultra-high molecular weight polyethylene is used.

In the reinforcing layer, reinforcing polymer tapes with a thickness of 0.5-2.0 mm and a width of 20 - 95 mm are used. Justification of the thickness and width of the applied tapes is given below.

As reinforcing metal tapes, a steel tape is used with a tensile strength above 600 MPa, a thickness of 0.3-1.5 mm, a width of 20 - 95 mm.

In the reinforcing layer, polymer threads or metal wires with a diameter of 0.2-2.0 mm are used.

As the polymer filaments, a polymeric material selected from the group: polyesters, polyolefins, ultra high molecular weight polyethylene, aramids is used.

The polymer layers included in the pipe design provide high corrosion resistance of the pipeline, low specific gravity and lower thermal conductivity compared to steel pipes. At the same time, polymer pipes and shells can be made in continuous lengths, and used polymer materials, such as polyethylene, allow the winding of pipes on technological and transport drums, the restriction on the length of the pipes is due only to transport capabilities. So, for example, a reinforced pipe with an internal diameter of 150 mm can be delivered in construction lengths of 200 m, and a pipe with an internal diameter of 100 mm with construction lengths of 600 m.With significant construction lengths of pipes, the number of mounting joints and, accordingly, the installation time of the pipeline as a whole are significantly reduced.

The use of reinforcing metal or polymer tapes, threads or wires provides mechanical strength of pipes up to 200 bar. As reinforcing elements, a metal tape with a strength of up to 800 MPa, polymer tapes with a strength of up to 450 MPa, polyester, aramid and other polymer threads can be used. The required number of tapes or threads is determined by calculation. For comparison: the average strength of the material of metal pipelines is about 400 MPa.

Polymers, unlike steel, are not subject to corrosion, which helps to increase the life of pipelines; have a lower heat transfer coefficient, which ensures lower heat loss of the transported fluid.

For example, the thermal conductivity coefficient for various metals is from 35 to 400 W / (m * K), and a similar coefficient for polymers has an average of 0.36 W / (m * K).

However, the basic heat-insulating properties of polymers may not be enough when operating the pipeline at low temperatures or when the fluid flow in it is stopped. In order to improve the heat-insulating properties, at least one more polymer layer (heat-insulating layer (8)) is introduced into the pipe structure, which has a significantly lower coefficient of thermal conductivity compared to polymer scraps forming the pipe body. In this case, the coefficient of thermal conductivity of polyethylene is 0.36 W / (m * K), and the coefficient of thermal conductivity of foamed polyethylene has an indicator of 0.06 W / (m * K). Those. the thermal conductivity of foamed polyethylene is 6 times less than ordinary polyethylene, respectively, the use of a layer of foamed polyethylene 1 cm thick in thermal insulation properties in a pipe design is similar to the thickness of a layer of ordinary polyethylene 6 cm, ceteris paribus. It should be noted that foamed polyethylene has very low strength characteristics and can be used only as an additional layer, and not the main structural element of the base of the polymer reinforced pipe.

The use of additional heat-insulating layers in the design of the pipe may not be sufficient for the operation of pipes in the winter period with their surface laying or in permafrost. For example, if during transportation through the pipes of water the pump stops for a long time, this will lead to freezing of the contents of the pipe.

Freezing of the transported fluid is prevented by introducing an additional layer into the pipe structure, consisting of coils (7) of insulated conductors (13) concentrically wound on the pipe body. Depending on the length of the heated section, the conductors can be made of metal materials (copper, aluminum or steel). The cross section of the conductors is calculated in such a way that the thermal power released during the passage of electric current at least compensates for the heat loss of the transported fluid into the environment. The electrical conductors are powered by alternating or direct current, with each phase having from one to 10 elementary conductors, i.e. split phase. The effectiveness of the use of a split phase is considered using an example of a three-phase heating system. For three-phase power supply of the pipeline heating system, for the compensation of losses and possible heating of the substance transported through the pipe, we need copper conductors with a cross section of 16 mm ² , diameter 4.5 mm in each phase, and the diameter on which the heating conductors are concentrically wound is 130 mm. If there is only one conductor in each phase, then the distance between the conductors around the circumference of their installation will be 130 * 3.14 / 3 = 136 mm, and the coefficient by filling the circumference with heating elements will be only 4.5 / 136 = 3.3%.

If you use a split phase and install instead of one conductor with a cross section of 16 mm ² eight conductors with a cross section of 2 mm ² (diameter 1.6 mm), then while maintaining the weight of the conductors and the total heating power, a more uniform distribution of heat power around the pipe circumference is obtained, and the fill factor with heating elements will be 8 * 1.6 / 136 = 9.4% or three times higher.

Insulated conductors laid in a wound (13) are mainly used to include them in an electric heating system, i.e. used as heating. However, part of the conductors can be used to transmit electrical energy as a power line to remote consumers or transmit information. In these cases, the conductors can be made with the necessary cross section or made in the form of twisted pairs (19). Optical modules (20) and optical fibers for high-speed data transmission systems or distributed measuring systems can also be stacked in a midwife. If the estimated number of conductors is sufficient to perform the above functions, and there is free space in the wound, it can be filled simply with fillers (21) to ensure the correct geometric shape of the pipe and the absence of voids.

Each elementary conductor of a round or rectangular shape has an insulating layer. Conductors can have an outer shell in the form of a sector of the ring, limited by the inner and outer radii of the laying of conductors. Sector conductors, in turn, may have mutually complementary protrusions at the edges for mutual engagement. If necessary, twisted-pair conductors, optical modules or just placeholders can be placed in a wound of insulated conductors. The proposed shape of the conductors due to the high degree of filling has an effective heat transfer through the polymer, which prevents overheating of the conductors, and due to the protruding elements of the sectors provides additional mechanical strength of the entire pipe structure.

When the conductors are connected to a power source, thermal energy is released into them, which is spent on heating or compensating for losses in the environment of the fluid transported through the pipeline. In this case, the main task of the heating conductors is to prevent freezing of the contents of the pipeline in the winter. The available power and information transfer conductors are used accordingly.

The claimed high-pressure reinforced polymer pipe is made as follows.

For the manufacture of a high-pressure reinforced polymer pipe, in accordance with option 1, an extruder is used, into which polymer material, for example, polyethylene, is loaded and heated to a viscous-flowing state and extruded through the forming head in the form of a continuous inner layer (1) that forms the basis of the pipe. The resulting pipe (inner layer (1)) is wound on a process drum. The external diameter of the pipe is from 40 to 219 mm, the wall thickness is from 3 to 20 mm. The specific wall thickness is selected by the SDR parameter (the ratio of the external diameter of the pipe to the wall thickness), which is usually 6 to 17 in the technique. Next, the polymer pipe (inner layer (1)) is fed to the winding unit of the polymer tape windings, in which the outer surface the inner layer (1) of the polymer pipe is covered with four coils (2-5) of polymer tapes, for example, of polyethylene terephthalate by winding using a twisting machine, with a tape winding angle of 55 ± 5 °. When winding polymer tapes, at least one winding (3-5) has the opposite winding direction, for example, the second winding (3) has the opposite winding direction with respect to the first winding (2), the third and fourth windings (4, 5) have a direction winding, which coincides with the first winding (2), or, for example, in accordance with another variant of winding: the first and second windings (2, 3) are wound in one direction, and the third and fourth windings (4, 5) have the opposite direction of winding . The winding of the coils (2-5) of polymer tapes is carried out in such a way that a gap is made between the polymeric tapes of each cove (2), amounting to 5-10% of the width of the tape, and the gap below the wound coils is closed above the wound coils. Reinforcing elements of polymer filaments or metal wires are also wound with at least two strands. An intermediate sheath (6) is applied by extrusion over the coils of reinforcing elements, after which the pipe is fed to the coils winder (7) from insulated conductors (13). After the coils winder (7) from insulated conductors (13), a polymer pipe with applied layers is fed into an extruder for applying an external polymer shell (10), in which, by extrusion, a continuous polymer layer, for example, polyethylene, forming an external polymer shell (10) of polymer polymer, is applied to a coil (7) from insulated conductors (13) loss. The thickness of the polymer sheath is also selected on the basis of the SDR parameter, the parameters of which in this case are from 5 to 15. In the final operation, a flexible polymer reinforced pipe containing 4 coils of polymer tapes, coiled from insulated conductors and the outer polymer shell are wound into a bay or onto transport drums. The continuous length wound around the transport drum of the claimed flexible polymer reinforced pipe with a diameter of 40 mm can be 2500 m, and with a diameter of 170 mm, 200 m.

Another embodiment of the pipe design is the application of a heat-insulating layer of 5 ÷ 15 mm thick on a half-wound through insulated conductors, over which a continuous twist of a thin metal tape 0.2 to 0.6 mm thick is wound, and an external polymer shell is applied by extrusion to the tape . A twist of thin metal tape protects the internal elements of the pipe from external influences. As experiments have shown, the claimed design of the pipe has high strength characteristics and low heat loss to the environment.

High-pressure polymer reinforced pipes can be used for surface mounting or for trench laying, as well as using directional drilling or a pipeline restoration method in which the pipe is pulled through a normal damaged steel pipe. High-pressure polymer reinforced pipes are ideally suited for pipeline restoration due to the possibility of maintaining pressure and independence from the structural integrity of the pipeline through which it extends. The use of deepening methods allows minimizing the impact on the environment, reducing the degree of impact on the topsoil.

High-pressure polymer reinforced pipes can also be installed above the ground and are ideal for applications in harsh climatic conditions, such as the tundra, where an open pipeline can be installed with minimal use of infrastructure, for example, supports, and in many cases can be installed in places not equipped with access for transport.

The invention has been disclosed above with reference to a specific embodiment. Other specialists may be obvious to other embodiments of the invention, without changing its essence, as it is disclosed in the present description. Accordingly, the invention should be considered limited in scope only below by the following claims.

Claims (5)

1. The polymer reinforced pipe, consisting of an inner polymer layer constituting the base of the pipe, on the outer surface of which a reinforcing layer, an intermediate polymer shell, is successively applied, twisted from insulated conductors having an additional outer shell in the form of a ring sector, limited by the inner and outer radius of the laying of conductors , and the outer polymer shell, while the reinforcing layer is made of coils of metal or polymer tapes, polymer threads or metal wires. 2. The pipe according to claim 1, characterized in that the outer shell of the insulated conductors has mutually complementary depressions and protrusions at the edges. 3. The pipe according to claim 1, characterized in that a heat-insulating layer is applied between the coil of insulated conductors and the outer polymer shell. 4. The pipe according to 1, characterized in that under the outer polymer sheath is applied a twist of a metal tape. 5. The pipe according to claim 1, characterized in that in the midi of the insulated conductors are conductors in the form of twisted pairs, optical modules or fillers.

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