Temperature-resistant structure sheath for coating pipeline

Abstract

A method of retrofitting a water conduit by placing a liner within the conduit wherein the liner comprises at least one tubular jacket impregnated with a curable resin or comprises a tubular jacket and a calibration jacket both impregnated with a curable resin.

Description

Technical Field

[0001] This invention relates to a method for modifying metal pipes, particularly zone heating pipes, which include a lining comprising a tubular sheath or a tubular calibration sheath. Another aspect of the invention relates to modification kits for metal pipes and their uses, as well as modified metal pipes. Background Technology

[0002] Metal pipes, especially district heating pipes, are typically buried and insulated, and are susceptible to damage due to the combination of high temperatures and humid environments that accelerate corrosion. When these metal pipes are damaged, repair or replacement is usually a time-consuming and costly undertaking. Pipe replacement may require, for example, opening trenches to install new pipes. In addition to the high cost, this work often causes numerous inconveniences, such as road closures, noise pollution, and prolonged network outages. Furthermore, only a short section can be replaced in a single step. Pipes can also be repaired using different lining repair techniques by installing tubular coating materials inside the pipes. These tubular coating materials are typically impregnated with radiation-curable or ultrasonically curable resins, as described in documents such as WO 9220504 A1, US 4,581,247, and US 4,680,066. In addition to retrofitting district heating pipes, it is also necessary to improve their thermal insulation.

[0003] Purpose of the invention Therefore, the object of this invention is to provide an easy-to-implement, rapid, and economical method for retrofitting metal pipes, particularly zone heating pipes. Especially for zone heating pipes, this method allows for the formation of a coating that simultaneously retrofits and improves the thermal insulation of these pipes. Another object of this invention is to provide a retrofit kit that enables easy implementation of this method. Summary of the Invention

[0004] To address the aforementioned problems, the present invention, in its first aspect, proposes a method for modifying a metal pipe by installing a lining inside the pipe, wherein the lining comprises at least one tubular sheath impregnated with a curable resin, or comprises a tubular sheath and a calibration sheath both impregnated with a curable resin, wherein... - The method in the first variant includes the following steps: a) Position the tubular sheath impregnated with curable resin inside the pipe by flipping it over; b) Curing the curable resin; The wall of the tubular sheath comprises stacked layers, which, prior to installation, are arranged from the inside out as follows: layer B-layer C; layer A-layer B-layer C; layer B-layer A-layer C; layer B-layer A-layer B-layer C; layer A-layer B-layer A-layer B-layer C; or, layer A-layer B-layer A-layer C; or - The method in the second variant includes the following steps: a1) Position layer C inside the pipe by flipping or translating it; a) Position the tubular sheath impregnated with curable resin within layer C of the pipe by flipping it over; b) Curing the curable resin; The wall of the tubular sheath comprises stacked layers, which, prior to installation, are arranged from the inside out as follows: layer B-layer C; layer A-layer B-layer C; layer B-layer A-layer C; layer B-layer A-layer B-layer C; layer A-layer B-layer A-layer B-layer C; or layer A-layer B-layer A-layer C; or - The method in the third variant includes the following steps: a) Position the tubular sheath impregnated with curable resin inside the pipe by translation; a2) Position the calibration sleeve impregnated with curable resin inside the tubular sleeve in the pipeline by flipping it over; b) Curing the curable resin; The wall of the tubular sheath comprises a stack of layers, which, before installation, from the inside out, are: layer B-layer C; layer A-layer B-layer C; layer B-layer A-layer C; layer B-layer A-layer B-layer C; layer A-layer B-layer A-layer B-layer C; or, layer A-layer B-layer A-layer B-layer C; and the wall of the calibration sheath comprises a stack of layer C or layers A-layer C from the inside out before installation; or - The method in the fourth variant includes the following steps: a) Position the tubular sheath impregnated with curable resin inside the pipe by flipping or translating; b) Curing the curable resin; The wall of the tubular sheath comprises stacked layers, which, prior to installation, are from the inside out: layer C-layer B-layer C; layer C-layer A-layer B-layer C; layer C-layer B-layer A-layer C; layer C-layer A-layer B-layer A-layer B-layer C; or, layer C-layer A-layer B-layer A-layer C; - Each time layer A appears, it independently represents a layer consisting of k sheets of woven or nonwoven fibers, including synthetic fibers, natural fibers, or mineral fibers or mixtures thereof, where k is an integer from 1 to 20; - Layer B, each time it appears, independently represents a layer comprising n sheets of synthetic, natural, or mineral woven or nonwoven fibers or mixtures thereof, comprising at least 30% by weight of fibers oriented radially to the tubular sheath, preferably at least 70% by weight of fibers oriented radially to the tubular sheath, and even more preferably 100% by weight of fibers oriented radially to the tubular sheath, referred to as reinforcing fibers, wherein the reinforcing fibers are selected from the following fibers: polyester fibers, polyamide fibers, acrylic fibers, phenolic fibers, aramid fibers, glass fibers, carbon fibers, ceramic fibers, basalt fibers, flax fibers, hemp fibers, or mixtures of two or more fibers of these types, and / or, the reinforcing fibers are selected from fibers with a toughness of 30 cN / tex (centineu / detertex) to 500 cN / tex, where n is an integer from 1 to 20; - Layer C, each time it appears, independently represents a fluid-sealed layer that is resistant to temperatures of at least 60°C, comprising or composed of polymers selected from the following: polyurethane, polyethylene, ethylene-propylene-diene polymer (EPDM), silicone, polypropylene, polyimide, polyether ether ketone (PEEK), polybenzimidazole, or mixtures thereof.

[0005] This invention relates to a method for modifying metal pipes, particularly metal pipes used in zone heating, wastewater treatment in the paper and / or chemical industries, offshore platforms, smelters, breweries, etc.

[0006] The proposed method for modifying pipelines has the advantage of being usable via both flip-insertion and translation-insertion methods. The choice of specific variations of the method will be influenced by the configuration of the pipeline to be modified and the requirements it must meet—namely, diameter, length, the presence or direction of curves, pressure, and fluid temperature within the pipeline.

[0007] Within the scope of this invention, the term "lining" refers to a tubular sheath impregnated with resin and positioned within a metal pipe to be modified, or a tubular sheath and calibration sheath impregnated with resin and positioned within a metal pipe to be modified.

[0008] In this invention, the term "sheet" refers to a sheet of woven or nonwoven fibers. These sheets can be overlapped to form a collection called a "layer". The term "layer" in this invention generally refers to a collection of one or more sheets comprising woven or nonwoven fibers, or a collection consisting of one or more sheets of woven or nonwoven fibers. A layer can comprise 1 to 20 sheets, preferably 1 to 5 sheets. Thus, a layer can comprise 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 sheets. The term "layer" can also refer to a layer composed of polymers, in which case the layer can be called a sealing and heat-resistant layer, or simply a sealing layer. Depending on the context, a layer according to the invention may therefore represent a collection of one or more sheets of woven or nonwoven fibers, in this case layer A and / or layer B; or a layer according to the invention may represent a polymer layer, in this case one or more layers C.

[0009] In this context, the term "positioning" refers to the initial insertion and installation of the liner into the pipe in one step by flipping or translating, or in two steps by translating the insertion of the tubular sheath followed by flipping the insertion of the calibration sheath, or in two steps by flipping or translating the tubular sheath (layer C) to insert the sealing layer followed by flipping the insertion of the calibration sheath. Then, after insertion, the liner expands to bring it close to the pipe wall to fit the pipe to be modified. Once the liner is positioned (step a), or step a1) followed by step a), or step a) followed by step a2), i.e., after the liner is installed and expanded, the curable resin is cured (step b), forming a rigid / solid liner that is shape-stable and capable of withstanding pressure (internal loads, external loads) and temperature conditions during the commissioning of the modified metal pipe.

[0010] Flip insertion means that the sheath is allowed to be advanced into the pipe when it is flipped out / reversed from the inside. Flip insertion implies that the layer that was on the outer part of the liner before positioning becomes the layer on the inner part of the liner after installation—that is, after being flipped out from the inside. During flip insertion, the sheath is allowed to be advanced under positive air or water pressure. Translation insertion means that the sheath is pulled into the pipe by translational movement without reversing the initial (pre-installation) order of the layers from the inside to the outside.

[0011] The liner advantageously includes a tubular sheath comprising a collection of layers B and C, or a collection of layers A, B, and C. Layer A comprises one or more sheets of woven or nonwoven fibers, including synthetic fibers, natural fibers, mineral fibers, or mixtures thereof; layer B comprises one or more sheets of woven or nonwoven fibers, including reinforcing fibers or so-called high-performance fibers; sealing layer C comprises a polymer and is located on the outer portion of the tubular sheath before installation. Therefore, layer C will always be positioned on the outer portion of the tubular sheath before installation, that is, sealing layer C will always be positioned on the outer surface of the tubular sheath before installation. When the liner is installed according to a fourth variant of the method, the tubular sheath also includes layer C located in the inner portion of the tubular sheath before installation, i.e., layer C located on the inner surface of the tubular sheath before installation. In other words, in variant 4, layer C is positioned on both the outer and inner portions of the tubular sheath before installation. Advantageously, the tubular sheath may include multiple layers A and / or multiple layers B, which are alternately overlapped to form a collection of layers of the tubular sheath. Prior to installation, the layers, from inside to outside, are: layer A-layer B; layer A-layer B-layer A; layer A-layer B-layer A-layer B; layer B-layer A; layer B-layer A-layer B; layer B-layer A-layer B; layer B-layer A-layer B-layer A. The tubular sheath always includes a sealing layer C located on the outer surface of its wall prior to installation. The polymer sealing layer C may be mechanically or non-mechanically bonded to adjacent layers A or B.

[0012] When the liner is installed according to the first variant of this method, i.e., when the tubular sheath is positioned by flipping, the layers are reversed, thereby the liner comprising either a collection of layers B and C or a collection of layers A, B, and C, with layer C positioned on the inner surface of the liner. Once positioned, layer A or layer B will be positioned against the wall of the pipe, while layer C will be located on the inner portion, thus positioned to contact the fluid within the modified pipe.

[0013] When the tubular sheath is positioned according to the third variant of the method, i.e., by translation in step a) and positioning in step a2), step a2) includes installing the calibration sheath inside the tubular sheath by flipping. In this configuration, the layer C of the tubular sheath, after installation, will be located on the outer portion of the liner, the sealing layer C thus contacting the pipe, while the calibration sheath is located in the inner portion of the liner, the sealing layer C of the calibration sheath located on the inner surface, positioned to contact the fluid within the modified pipe. The tubular sheath and the pipe are thus isolated and protected from the circulating (high-temperature) fluid.

[0014] The liner has a certain degree of flexibility and adaptability to allow it to be inserted into the pipe, especially during the flipping step, that is, when the liner is inserted into the pipe by flipping the inside out, and during the expansion step.

[0015] Depending on the pipe configuration, those skilled in the art will choose to position the liner by flipping or by translating and then flipping, depending on the variation of the method. For pipes including "bends" or changes in orientation, the first variation of the method—i.e., the flipping version (according to step a)—is preferred over the third variation of the method, which is the translation followed by flipping version (according to steps a) and a2). When the distance between the two inlets and outlets of the pipe is large, the liner is preferably installed according to steps a) and a2) of the third variation of the method.

[0016] Within the scope of this invention, the expression "impregnated with curable resin" means that all layers forming the tubular sheath and calibration sheath—except for one or more sealing layers C—are impregnated with curable resin. Impregnation of the tubular sheath and calibration sheath is typically completed before the bushing is installed into the conduit. After impregnation, the resin enters the sheath, and advantageously, the sealing layer located outside the tubular sheath and / or calibration sheath prevents resin flow before the sheath is positioned in the conduit.

[0017] When the tubular sheath is installed by flipping, the resin-impregnated layer will adhere to the pipe wall during the flipping process. In this configuration, the lining can be attached to the wall during the curing step if necessary.

[0018] When the tubular sheath is installed by translation, and then the calibrated sheath is installed by flipping (according to the third variant of the method, step a) then step a2), the sealing layer C of the tubular sheath will adhere to the wall, and the resin, after curing, will generally not adhere to the pipe wall. This configuration can enhance the resistance to pipe movement caused by external factors (such as ground motion, earthquakes, etc.) or by expansion effects caused by pipe operating conditions (such as temperature changes).

[0019] When positioning according to the third variant of the method is not possible, particularly due to size and / or shape limitations of the pipe to be modified, those skilled in the art may choose to install the sealing layer C by step a1) prior to step a). Step a1) can be performed by flipping or pulling the layer C. After the layer C is installed inside the pipe, the tubular sheath is installed according to step a), so that the layer C is located between the pipe and the tubular sheath, serving as a protective and sealing layer. Advantageously, after installation according to step a1) and then step a) (the second variant of the method), the lining is not directly attached to the wall, thus providing better resistance to dimensional changes caused by the expansion / contraction of the metal pipe due to temperature variations during commissioning and use. The lining positioned in this way will not adhere to the metal pipe after expansion, thus reducing the likelihood of breakage or embrittlement depending on external conditions.

[0020] Those skilled in the art can also install the liner according to a fourth variation of the method. In this variation, the tubular sheath comprises two sealing layers surrounding the assembly of layers A and B, or layer B, and can be positioned within the pipe by flipping or pulling. Advantageously, after installation, the tubular sheath will comprise a sealing layer C directly abutting the wall and a sealing layer C on the inner surface of the liner that is in direct contact with the fluid. The liner thus positioned will not adhere to the wall and will be protected from fluid influence by the presence of the inner layer C.

[0021] Liners used for retrofitting and reinforcing pipes also possess tear and abrasion resistance, especially during the positioning step. In fact, when inserted into the pipe to be retrofitted by flipping or translating, the lining must be able to resist roughness and defects such as corrosion in the pipe's interior, and it must also be puncture-resistant during the expansion step, i.e., when close to the pipe wall under air pressure.

[0022] Once the resin has cured, the lining becomes rigid, shape-stable, and strong enough to withstand the internal pressure generated by the flow of fluid. The lining must allow the fluid to pass through efficiently.

[0023] According to a preferred embodiment, layer A comprises k layers of woven or nonwoven fibers. The woven or nonwoven fibers include synthetic fibers, natural fibers, or mineral fibers, or mixtures thereof, where k is an integer from 1 to 20, preferably an integer from 1 to 5. Preferably, layer A comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 layers. The synthetic fibers are preferably selected from: polyester fibers, polyamide fibers, acrylic fibers, phenolic resins, aramid fibers, or mixtures thereof. The mineral fibers are preferably selected from: glass fibers, carbon fibers, ceramic fibers, basalt fibers, etc., or mixtures thereof. The natural fibers are preferably selected from: flax fibers, hemp fibers, fiber, etc., or mixtures thereof. Preferably, layer A comprises one, two, three, four, or five sheets of woven or nonwoven fibers selected from the following fibers: polyester fibers, polyamide fibers, acrylic fibers, natural fibers, or recycled flax fibers or blends thereof.

[0024] According to another preferred embodiment, layer B comprises n sheets of synthetic, natural, or mineral woven or nonwoven fibers. Layer B includes at least 30% by weight of fibers oriented radially along the tubular sheath, preferably at least 70% by weight of fibers oriented radially along the tubular sheath, more preferably 100% by weight of fibers oriented radially along the tubular sheath, the fibers being referred to as reinforcing fibers. The reinforcing fibers are selected from the following fibers: polyester fibers, polyamide fibers, acrylic fibers, phenolic fibers, aramid fibers, glass fibers, carbon fibers, ceramic fibers, basalt fibers, flax fibers, hemp fibers, or mixtures of two or more fibers of these types, and / or, the reinforcing fibers are selected from fibers with a toughness of about 30 cN / tex to about 500 cN / tex, where n is an integer from 1 to 20. Preferably, layer B comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 layers. Within the scope of this invention, the reinforcing fiber is a fiber with resistance to tensile stress and high-pressure deformation, capable of reinforcing the tubular sheath and preventing its deterioration under pressure. The reinforcing fiber according to the invention is a fiber capable of providing good pressure resistance to layer B, resisting deformation caused by pressure. Pressure resistance can be characterized by the toughness of the material, i.e., the material's ability to resist crack propagation. The toughness of a fiber or fabric is defined by the elastic limit of the material, i.e., the force that the material can withstand and then recover its original shape without deformation, measured in centinewtons per tex (cN / tex). Toughness is measured using a dynamometer. The reinforcing fiber forming layer B has a toughness value of approximately 150 cN / tex, preferably approximately 250 cN / tex. Pressure resistance is also defined by flexural modulus. Flexural modulus represents the pressure applied to deform the pipe, expressed in MPa. The resin-impregnated layer B—i.e., a composite comprising woven or nonwoven reinforcing fibers and a curable resin—will have a flexural modulus of about 2,000 MPa to about 50,000 MPa, preferably about 5,000 MPa to 10,000 MPa, and even more preferably about 7,500 MPa to about 20,000 MPa. Depending on the inherent pressure stress of the pipe to be modified, layer B typically comprises one or more layers of reinforcing fibers. The fibers constituting layer B will be selected from glass fibers, carbon fibers, or mixtures thereof that have high pressure resistance. Layer B typically comprises at least 30% reinforcing fibers by weight, preferably at least 70% reinforcing fibers by weight, and even more preferably at least 100% reinforcing fibers by weight. To ensure the correct positioning of the tubular sheath and improve its mechanical properties, layer B is typically positioned between two layers, such as between layer A and sealing layer C, or between two layers A, or between two sealing layers C.More specifically, in the case of small-diameter pipes, layer B will preferably comprise a combination of nonwoven glass fiber sheets and woven glass fiber sheets. Preferably, layer B comprises one, two, three, four, or five sheets of woven or nonwoven reinforcing fibers, which are preferably woven or nonwoven glass fibers. Layer A of the tubular sheath and layer A of the calibration sheath can each independently comprise 20% to 80% by weight of reinforcing fibers, particularly 25% to 50% by weight, and preferably about 30% by weight.

[0025] The inventors unexpectedly observed that layer B, composed of reinforcing fibers, offers a dual advantage. First, layer B allows for reinforcement of the sheath, making it more pressure-resistant and thus enhancing its mechanical properties, while reducing the number of woven or nonwoven fiber layers (layer A) required to achieve the same pressure resistance without high-performance fibers. Second, the presence of layer B allows for a reduction in the number of layers with the same mechanical efficiency, resulting in a thinner lining and consequently lower manufacturing costs, while also reducing the amount of resin required to impregnate the tubular sheath and, where applicable, to calibrate it. The reduced lining thickness facilitates installation within the modified pipe, where the reduction in the pipe's inner diameter is smaller, thus limiting the decrease in fluid flow rate after modification due to the reduced effective diameter.

[0026] According to the present invention, layer C comprises or is composed of a fluid-tight layer resistant to temperature and chemicals. The sealing layer is a polymer layer, preferably selected from polyurethane, polyethylene, ethylene-propylene-diene (EPDM) polymer, silicone, polypropylene, polyimide, polyetheretherketone (PEEK), polybenzimidazole, or mixtures thereof. This sealing layer C can be mechanically or non-mechanically bonded to a sheet (or more sheets) of woven or non-woven fibers of adjacent layer A or layer B by means of extrusion, spraying, or adhesion. Therefore, when the tubular sheath is installed by flipping, the sealing layer C will be located on the inner surface of the lining. The sealing layer C allows for the isolation of layer A and / or layer B from the fluid circulating within the pipe (the fluid may be at high temperatures, such as 60°C to 400°C or even higher), thereby preserving the initial insulation properties of these layers and improving and optimizing the pipe's insulation properties by reducing heat loss of the (high-temperature) fluid during the modification of the pipe's internal circulation. In addition to isolating the layers, one or more sealing layers C also allow the inner surface of the pipe to be isolated and prevent corrosion and abrasion caused by the (high-temperature) fluid passing through.

[0027] Advantageously, the sealing layer C comes into contact with the fluid circulating within the pipe. According to the invention, the metal pipe to be modified involves a pipe in which fluids at high temperatures and with different pH values ​​can be circulated. The sealing layer C will be selected based on fluid-related constraints. Preferably, the sealing layer C is heat-resistant, for example, heat-resistant during commissioning of the modified metal pipe, for example, continuously resistant to temperatures from about 60°C to 200°C, preferably continuously resistant to temperatures from about 150°C, and resistant to peak temperatures of about 180°C, 190°C, 200°C, 300°C, and / or 400°C. Within the scope of the invention, resistance to continuous temperatures means that one or more sealing layers will withstand temperatures from about 60°C to 200°C, that is, the sealing layer will be able to withstand the temperature of the circulating fluid at a constant temperature throughout the entire service life of the lining. During the use of the modified pipe, temperature changes may occur, particularly temporary fluctuations in fluid temperature. Within the scope of the invention, peak temperature refers to the temperature that the fluid may temporarily reach during the use of the modified pipe. Advantageously, one or more sealing layers withstand these temperature changes, more specifically, one or more sealing layers withstand peak temperatures of approximately 180°C, 190°C, 200°C, 300°C, and / or 400°C, meaning that layer C is able to maintain its sealing and temperature resistance properties. Preferably, the sealing layer C withstands pH values ​​from 1 to 14, and the properties of the polymer will be selected according to the intended use of the modified pipe, i.e., the properties of the polymer will be selected based on the properties (physicochemical properties, such as pH value) and temperature of the fluid circulating in the pipe.

[0028] One advantage of the lining described in this invention is its insulating ability. The combination of layers A, B, and C reduces heat loss by adding continuous layers and / or sheets that thermally insulate the pipe from the fluid, thereby reducing energy loss when delivering the fluid to the desired temperature at the target location, thus enabling an improvement and increase in the pipe's insulating ability. Those skilled in the art can adjust the number and thickness of the layers by adjusting the number of fiber sheets according to the diameter of the pipe to be modified and the required mechanical and thermal insulation properties. One advantage of this invention is that the lining thickness can be adjusted by adjusting the number of layers and sheets according to the constraints associated with pipe modification. Increasing the lining thickness inevitably reduces the inner diameter of the modified pipe, i.e., the effective cross-section of the modified pipe. Unexpectedly, this loss of usable cross-section is compensated by the insulating effect of the lining and the improvement in the mechanical properties of the lining.

[0029] The lining will advantageously have 0.0025 Wm -1 .K -1 Up to 0.25 Wm -1 .K -1 The thermal conductivity is preferably 0.2 W / m. -1 .K -1Thermal conductivity. Thermal conductivity represents a material's ability to conduct heat through it and can be measured using the hot wire method. Advantageously, compared to unmodified pipes, linings can reduce energy loss by at least 25% due to the insulating effect of the lining.

[0030] Depending on limitations related to commissioning, pipe size, and / or thermal insulation, those skilled in the art can select the appropriate lining according to variant 1, variant 2, variant 3, or variant 4. Positioning according to step a) of the first variant can provide thermally insulated piping from layers A and / or B and C, while the sealing layer C, in direct contact with the (high-temperature) fluid, isolates the felt sheets from the fluid circulating within the pipe. In the case of installation according to steps a) and a2) of the third variant of the method, the lining will comprise an outer sealing layer C and an inner sealing layer C, the outer sealing layer C being in direct contact with the inner portion of the pipe, and the inner sealing layer C being positioned to contact the (high-temperature) fluid. This additional sealing layer C has the additional advantage of improved thermal performance of the lining. In fact, the fourth layer, on the one hand, allows for the addition of additional fiber sheets, which in principle enhances the thermal insulation effect and improves mechanical properties; on the other hand, it provides a second sealing layer C that directly contacts the inner wall of the modified pipe. Each of the one or more layers C, each occurring independently, has a thickness between about 0.2 mm and about 1.5 mm, preferably about 0.5 mm. Similar to positioning the tubular sheath by flipping, in the positioning process according to the third variant, following steps a) and a2), the sealing layer C—specifically, the sealing layer C of the calibrating sheath—comes into contact with the (high-temperature) fluid circulating inside the pipe, then acts as a conduit for the (high-temperature) fluid, and prevents the (high-temperature) fluid from penetrating the felt sheets of layers A and B, which would reduce the insulation capacity of layers A and B. Furthermore, in this case, the tubular sheath is positioned by traction, with the sealing layer C of the tubular sheath contacting the inner wall of the pipe. The advantage of this method is that it prevents water from penetrating to the outside of the pipe, for example, in the event of pipe damage due to external factors. This external seal allows the insulation and thermal performance of the lining to be maintained even if the outside of the pipe deteriorates. A combination of layers C-B-C or layers C-A-B-C, or possible combinations installed according to the third variant of the method, provides improved thermal insulation even in these cases. Therefore, when thermal insulation is a critical factor, positioning according to steps a) and a2) of the third variant of the method is preferred.

[0031] Another advantage of the sealing layer C, which is in direct contact with the circulating fluid, is its typically smooth surface formed by the polymer layer. In fact, in the case of unprotected and unmodified pipes, deposits can form on the inner wall due to factors such as corrosion, creating roughness and leading to increased pressure loss. The presence of a corrosion-resistant polymer layer on the inner wall of the liner allows for a generally smooth surface that changes very little or not at all over time, maintaining a constant pressure loss over time. Therefore, the pressure loss that might result from a reduction in inner diameter due to the liner can be compensated for by a smoother and less corroded inner surface—an advantage that cannot be achieved, for example, by isolating the pipe from the outside.

[0032] Generally, in addition to the pipe configuration, those skilled in the art will determine the positioning method based on parameters such as pressure, temperature, pipe diameter, and pipe depth, according to the first, second, or third variant of the method.

[0033] The commissioning and use of metal pipelines involve numerous physical and technical limitations, such as corrosion due to fluid properties, high temperatures, and humidity; the presence of water hammer; energy loss; and pipe expansion with temperature. Water hammer is an overpressure phenomenon that occurs when fluid velocity changes abruptly—for example, when a valve is opened or closed. Lining and modification methods must be able to withstand these various limitations. Advantageously, the lining and modification methods of the present invention allow for the optimization of various parameters based on the constraints associated with the pipeline to be modified. In practice, the properties and composition of the lining—particularly the composition and number of layers A and B, and the number of layers A, B, and C in the lining—will be determined based on the limitations associated with the commissioning and use of the modified pipeline. As previously mentioned, a sealing layer C exists between the wall and the tubular sheath to prevent the tubular sheath from adhering to the pipe wall, thus the lining does not follow the movement of the pipe wall. The properties of the polymer of layer C—whether layer C is located on the inner portion of the lining or simultaneously on both the inner and outer portions (against the pipe wall)—will be determined based on the temperature and pH of the fluid in contact with layer C, as well as the potential for water hammer and energy loss. The number and properties of one or more layers A will be determined based on potential water hammer and significant external loads. Adjusting the number of layers A and the number of layers A allows for adjustment of the final lining thickness to compensate for any air voids and to reinforce the lining against external loads. Furthermore, adjusting the number of layers A allows for optimization of energy loss by isolating the pipe from the fluid, thereby reducing heat exchange between the inside and outside of the lining. The presence, properties, and number of reinforcing layers B, as well as the number of layers B, can be determined based on the pressure within the pipe to be modified.

[0034] A sheet (or more sheets) of woven or nonwoven fibers of one or more layers A independently comprises the same material each time it appears, and may include 20% to 80% by weight of reinforcing fibers, preferably 30% by weight of reinforcing fibers.

[0035] According to one embodiment, the tubular sheath may include one or more layers A and B that overlap alternately, and the tubular sheath always has a sealing layer C on its outer portion before installation. Therefore, the tubular sheath may have configurations such as, before installation, layers A-B-A-C, A-B-A-C, B-A-B-C, or even B-A-B-A-C.

[0036] According to another preferred embodiment of the invention, when the liner is installed according to a third variant of the method, i.e., when step a) is performed by pulling, the method further includes a subsequent step a2) of positioning the calibration sleeve. The calibration sleeve comprises a layer or layer C having a combination of layers A and C. The calibration sleeve may comprise one or more layers A of the tubular sleeve made of the same material. When the calibration sleeve comprises layers A and C, the sealing layer C is located on the outer portion of the calibration sleeve before installation. When the liner is installed in this manner, the sealing layer C of the tubular sleeve is positioned against the pipe, the sealing layer C being located on the outer portion in contact with the pipe. The calibration sleeve is positioned within the tubular sleeve by flipping and, after positioning, is located on the inner portion of the liner, forming an additional thermal insulation layer; the sealing layer C of the calibration sleeve is positioned in contact with the (high-temperature) fluid after the flipping installation.

[0037] Another advantage of this invention is that the lining's insulating ability is enhanced regardless of whether it is positioned according to the first, second, or third variant of the method. This increased insulating ability allows for compensation of flow losses caused by the reduction in the inner diameter of the modified pipe, and typically eliminates the need to replace installation components, such as pump systems used to distribute (high-temperature) fluids. Furthermore, when the lining is installed according to the second, third, or fourth variant, the sealing layer C remains in contact with the inner wall of the pipe. Positioning the sealing layer against the wall prevents the felt layer from being penetrated by water originating from outside the pipe in the event of corrosion or damage caused by external factors.

[0038] Advantageously, the liner comprises multiple layers overlapping each other, facilitating its positioning within the pipe. This overlap allows for greater freedom of movement and flexibility in positioning the overlapping layers, and thus the liner itself, during positioning within the pipe (e.g., by flipping). In fact, the overlapping layers can slide against each other during flipping or pulling. Therefore, surprisingly, at the same thickness, a multi-layered liner is easier to install than a single-layered liner. Consequently, the overlap of layers allows for the installation of thicker liners than a single-layered liner while maintaining pressure resistance and thermal insulation properties.

[0039] Advantageously, since internal temperature and humidity affect pipe aging, the modification method according to the present invention can protect the pipe from further premature aging.

[0040] Once positioned, the resin can be cured by any known method, including heat, electromagnetic radiation, room temperature crosslinking, etc. Advantageously, the resin is cured by heating, with the heat source selected from steam, hot water, and / or infrared (IR) radiation. In another embodiment, curing can be carried out by ultraviolet light, microwaves, ultrasound, irradiation, etc. Advantageously, regardless of the previously selected crosslinking method, "post-curing" can occur when the network reopens due to the fluid circulation temperature being higher than the resin crosslinking temperature.

[0041] Preferably, the curable resin comprises or is composed of polymers selected from the following: epoxy resin, polyester, vinyl ester, silicone, polyimide, polyamide, silicate, polybenzimidazole, polymethacrylate, furan, polyetheretherketone (PEEK), and thermoplastic polyurethane (TPU) resin; preferably, the curable resin comprises or is composed of polymers selected from the following: epoxy resin and vinyl ester resin. According to the invention, the curable resin is a resin that can be cured under heat, at room temperature, or by electromagnetic radiation (ultraviolet, infrared, microwave, ultrasonic, etc.). Typically, tubular sheaths and / or calibration sheaths can be impregnated with the curable resin in the field or at the factory. The curable resin can be cured at room temperature. During factory impregnation, tubular sheaths and / or calibration sheaths (whose layers A and / or B have been impregnated) can be stored for extended periods, provided that temperature and light conditions are carefully monitored.

[0042] Preferably, the lining has a thickness between 1.5 mm and 30 mm before installation, particularly between 1.75 mm and 25 mm, and advantageously between 2.0 mm and 20 mm before resin curing. Preferably, the modified pipe reduces its inner diameter by 1% to 8% of the initial inner diameter after installation—that is, after the resin has expanded and cured—preferably by 3% of the initial diameter.

[0043] The lining thickness can be selected based on the pipe's operating parameters (such as internal pressure and temperature) and its degradation state. The thickness must generally conform to the Normalized Dimension Ratio (SDR) constant, which is defined as the ratio between the lining's outer diameter (D) and the minimum thickness (e), and is therefore dimensionless. SDR = D / e.

[0044] Within the scope of this invention, the lining thickness is preferably selected to meet the so-called SDR100 requirement, meaning the SDR value must be at most 100. In other words, for a given pipe diameter, the minimum thickness of the lining after installation must be selected to have an SDR of 100 (SDR100). Therefore, the lining thickness after installation can have a value less than SDR100, with the reduction in the inner diameter of the modified pipe being 1% to 20% of the initial pipe diameter, preferably 1% to 8%, and more preferably 3%.

[0045] The lining thickness can also be determined according to the ASTM-F1216-22 standard published in March 2022, which covers procedures for retrofitting pipes by reversing.

[0046] Generally speaking, the closer the SDR is to 100, the better the lining's resistance to internal pressure.

[0047] Those skilled in the art will select the number of layers, the number of sheets per layer, and the nature of the woven or nonwoven fibers that make up the sheets, based on the characteristics of the thermal insulation, mechanical resistance, thickness, and installation conditions (by tensioning or flipping) of the pipeline to be modified.

[0048] According to a particularly preferred embodiment, the metal pipe is modified by installing a liner inside the pipe, wherein, according to a first variant of the method, the liner comprises at least one tubular sheath impregnated with a curable resin, or comprises a tubular sheath impregnated with a curable resin and a calibration sheath impregnated with a curable resin, wherein the tubular sheath comprises a stack of layers A-B-A-C from the inside out before installation. In this embodiment, layer B is located between two layers A. It can be observed that, in this configuration, reinforcing layer B allows for improved mechanical properties of the assembly of layers (i.e., layers A and C), thereby improving the properties of the tubular sheath.

[0049] When installation according to the third variant of the method is not feasible, particularly due to limitations related to the size and / or shape of the pipe to be modified, those skilled in the art may choose to install the liner according to the second variant of the method, installing the sealing layer C according to step a1) before step a), which can be done by flipping or pulling. Then, the tubular sheath is installed according to step a). Thus, the sealing layer C is positioned between the pipe and the tubular sheath, serving as both a protective and sealing layer. Advantageously, after installation according to step a1 followed by step a), the tubular sheath is not directly attached to the wall, thus providing greater resistance to dimensional changes in the metal pipe caused by expansion / contraction due to temperature variations during commissioning and use. The liner, thus positioned, does not adhere to the metal pipe after expansion, therefore reducing the likelihood of breakage or embrittlement depending on external conditions.

[0050] Another advantage of this method is that it allows for the selection of installation variants based on the configuration of the pipeline to be modified, thereby enabling the modification of all buried and overhead pipelines with lengths ranging from approximately 150 meters to 200 meters or longer in a single operation. Furthermore, this method allows for the modification of pipelines with directional changes without removing bends.

[0051] Within the scope of this invention, layers A, B, and C are as described above.

[0052] According to a second aspect of the invention, the present invention relates to a modification kit for metal pipes, the modification kit comprising at least one tubular sheath and a curable resin, wherein the wall of the tubular sheath comprises a stack of layers, the layers being, from the inside out, prior to installation: layer B-layer C; layer A-layer B-layer C; layer B-layer A-layer C; layer B-layer A-layer B-layer C; layer A-layer B-layer A-layer B-layer C; or, layer A-layer B-layer A-layer C.

[0053] According to another preferred embodiment, the retrofit kit for metal pipes includes a sealing layer C, a tubular sheath, and a curable resin, wherein the wall of the tubular sheath comprises a stack of layers, the layers from the inside out being: layer B-layer C; layer A-layer B-layer C; layer B-layer A-layer C; layer B-layer A-layer B-layer C; layer A-layer B-layer A-layer B-layer C; or, layer A-layer B-layer A-layer C. According to another preferred embodiment, the retrofit kit further includes a calibration sheath, wherein the wall of the calibration sheath comprises a stack of layers C before installation or layers A-layer C from the inside out.

[0054] According to another embodiment, the modification kit includes a tubular sheath and a curable resin, the wall of which comprises stacked layers, the layers being, from the inside out, as follows before installation: layer C-layer B-layer C; layer C-layer A-layer B-layer C; layer C-layer B-layer A-layer C; layer C-layer A-layer B-layer A-layer B-layer C; or, layer C-layer A-layer B-layer A-layer C. According to a third aspect of the invention, the present invention relates to a modified metal pipe, the modified metal pipe comprising a cured lining comprising a stack of layers, the layers from the outside to the inside being: layer B-layer C; layer A-layer B-layer C; layer B-layer A-layer C; layer B-layer A-layer B-layer C; layer A-layer B-layer A-layer B-layer C; layer A-layer B-layer A-layer C; layer C-layer B-layer C; layer C-layer A-layer B-layer C; layer C-layer A-layer B-layer C; Layer C-Layer B-Layer A-Layer C; is Layer C-Layer B-Layer A-Layer B-Layer C; is Layer C-Layer B-Layer A-Layer B-Layer A-Layer C; is Layer C-Layer A-Layer B-Layer A-Layer B-Layer C; is Layer C-Layer A-Layer A-Layer B-Layer C; is Layer C-Layer B-Layer A-Layer A-Layer C; is Layer C-Layer B-Layer A-Layer B-Layer A-Layer A-Layer C; or, is Layer C-Layer A-Layer B-Layer A-Layer A-Layer C.

[0055] Within the scope of this invention, layers A, B, and C are defined as described above after curing.

[0056] According to another aspect of the invention, the present invention relates to the use of a retrofit kit for modifying the internal coating of water pipes, particularly for district heating pipes.

[0057] In the context of this invention, all referenced numerical values, whether or not explicitly preceded by the term "about", represent a range of values ​​from -10% to +10%, preferably from -5% to +5%, and particularly from -2.5% to +2.5%. Attached Figure Description

[0058] Other features and characteristics of the invention will become apparent from the following detailed description of some advantageous embodiments presented by way of example, with reference to the accompanying drawings. These drawings illustrate: Figure 1 : This is the cross-section of the tubular sheath before installation; Figure 2 : is the cross section of the lining after installation, performed by pulling in step a) and then step a2). Detailed Implementation

[0059] Figure 1A cross-section of a non-flipped tubular sheath 10, designed for the retrofitting of metal pipes, is shown. The tubular sheath 10 comprises, from the inside out, layers A 11, B 12, A 13.b, and C 13.a. Layer C 13.a, located in the inner portion after flipping installation, is composed of a polymer and is mechanically or non-mechanically bonded to layer A 13.b, which consists of one or more woven or non-woven fiber sheets. Layer A 13.b is typically composed of a flexible woven or non-woven material (sheets), such as synthetic fiber felt or a mixture of synthetic fibers and / or mineral fibers and / or natural fibers. Sealing layer C 13.a generally comprises or is composed of polymers selected from the following: polyurethane, polyethylene, ethylene-propylene-diene (EPDM) polymer, silicone, polypropylene, polyimide, polyetheretherketone (PEEK), polybenzimidazole, or mixtures thereof. Sealing layer C 13.a is designed to isolate the structural sheath from the conduit and fluid. The tubular sheath is designed such that layer 13.a is located on the outer surface of the tubular sheath to facilitate handling of the tubular sheath. Furthermore, the tubular sheath is also designed to be impregnated with a curable resin. Therefore, the impregnable layer of the tubular sheath—i.e., the layers of the tubular sheath other than sealing layer C—is impregnated with the resin, and sealing layer C 13.a allows the impregnating resin to be isolated before installation into the conduit, thereby preventing the impregnating resin from flowing out of the tubular sheath during handling.

[0060] Layer B 12 of the tubular sheath, comprising or composed of reinforcing fibers, is placed between layers 11 and 13 to form the tubular sheath. The layers of reinforcing fibers may include or consist of glass fibers, carbon fibers, or aramid fibers, or mixtures thereof. This intermediate layer enhances resistance to internal pressure, preventing deterioration of the tubular sheath. The thickness and number of reinforcing fiber layers are determined based on the characteristics of the pipe to be modified—i.e., pipe size, fluid temperature, and pressure.

[0061] Layer A 11 will be located on the outside after being installed by flipping. Layer A 11 generally comprises or is composed of the same (or similar) material as layer 13.b, or layer A 11 generally comprises or is composed of one or more sheets of synthetic woven or nonwoven fibers and / or mineral fibers and / or natural fibers or mixtures thereof.

[0062] Figure 2A cross-section of a liner 20 installed by translation during step a) according to a third variant of the method is shown, the liner 20 also including a calibration sleeve 14 installed by flipping during step a2). The calibration sleeve comprises a set of layers AC, layers A and C being 14.b and 14.a, respectively. For clarity, the curable resin and the tubular conduit are not shown in the figure. The tubular conduit, positioned by translation, comprises, from the outside to the inside, a sealing layer C 13.a, layer A 13.b, a reinforcing layer B 12, and layer A 11. The tubular conduit is positioned by translation, with the sealing layer C 13.a located on the outer portion of the liner, that is, the sealing layer C 13.a in contact with the conduit. One advantage of this embodiment is that the liner can remain non-adhesive to the conduit, thereby allowing the liner to generate greater resistance to the movement of the conduit. The calibration sleeve 14 is then installed inside the tubular conduit by flipping during step a2). The calibration sleeve is installed by flipping it over, with the sealing layer C 14.a located on the inner surface of the liner, meaning that the sealing layer C 14.a is in contact with the (high-temperature) fluid.

[0063] Example A: Example A describes a liner used for retrofitting a pipe that previously had an inner diameter of 150 mm. Pipe parameters are summarized in Table 1.

[0064] Table 2 describes the final minimum thickness after installation of liners 1, 2, and 3 for modifying the pipes in Table 1, along with their corresponding initial (before installation) thicknesses. For liner 1, the thickness is defined by the SDR100 constant (SDR = 150 / 1.5 = 100), and for liners 2 and 3, the thickness is defined by the ASTM-F1216-22 standard.

[0065] Table 3 describes the composition and thickness (before installation) of each layer of liners 1, 2, and 3. Liner 1 is installed according to a second variation of the method, i.e., installed by flipping following step a1) and then step a). Liner 2 is installed according to a first variation of the method, i.e., installed by flipping following step a). Liner 3 is installed according to a third variation of the method, i.e., installed by pulling following step a) and then step a2). The final thickness after installation corresponds to the thickness of the installed liner after expansion and resin curing. The initial thickness corresponds to the thickness of the liner before installation, with the liner impregnated with curable resin.

[0066] Table 1: Parameters of the pipeline to be modified

[0067] Table 2:

[0068] Table 3:

[0069] Example B: Example B describes a lining used to modify a pipe that originally had an inner diameter of 600 mm. The pipe parameters are summarized in Table 4.

[0070] Table 5 describes the final minimum thickness after installation of liners 4, 5, and 6 for the modification of the pipes in Table 1, along with their corresponding initial (before installation) thicknesses. For liner 4, the thickness is defined by the SDR100 constant (SDR=600 / 6=100), and for liners 5 and 6, the thickness is defined by the ASTM F1216-22 standard.

[0071] Table 6 describes the composition and thickness (before installation) of each layer of liners 4, 5, and 6. Liner 4 is installed according to a second variant of the method, i.e., by flipping following step a1), liner 5 is installed according to a first variant of the method, i.e., by flipping following step a), and liner 6 is installed according to a third variant of the method, i.e., by pulling following step a1), followed by step a2). The final thickness after installation corresponds to the thickness of the installed liner after expansion and resin curing. The initial thickness corresponds to the thickness of the liner before installation, with the liner impregnated with curable resin.

[0072] Table 4:

[0073] Table 5:

[0074] Table 6:

[0075] Examples A and B describe a method for modifying metal pipes of different diameters. The installation method can be adjusted according to the lining thickness and the pipe configuration.

[0076] Figure label: 10 tubular sheaths 11th floor A 12th Floor B 13.a Sealing layer C 13.b layer A 14 Calibration Sheath 14.a Sealing layer C 14.b layer A 20. Lining according to the third variant of the method.

Claims

1. A method for modifying a metal pipe by installing a lining inside the pipe, wherein, The lining comprises at least one tubular sheath (10) impregnated with a curable resin, or comprises a tubular sheath (10) impregnated with a curable resin and a calibration sheath (14) impregnated with a curable resin, wherein... -The method in the first variant includes the following steps: a) Position the tubular sheath (10) impregnated with curable resin inside the pipe by flipping it over; b) Curing the curable resin; The wall of the tubular sheath (10) comprises stacked layers, which, before installation, are arranged from the inside out as follows: layer B-layer C; layer A-layer B-layer C; layer B-layer A-layer C-layer B-layer A-layer B-layer C; layer A-layer B-layer A-layer B-layer C; or, layer A-layer B-layer A-layer C; or -The method in the second variant includes the following steps: a1) Position layer C (13.a, 14.a) within the pipe by flipping or translating it; a) Position the tubular sheath (10) impregnated with curable resin within the layer C (13.a, 14.a) inside the pipe by flipping it over; b) Curing the curable resin; The wall of the tubular sheath comprises stacked layers, which, before installation, from the inside out, are: layer B-layer C; layer A-layer B-layer C; layer B-layer A-layer C; layer B-layer A-layer B-layer C; layer A-layer B-layer A-layer B-layer C; or, layer A-layer B-layer A-layer C; or - The method in the third variant includes the following steps: a) Position the tubular sheath (10) impregnated with curable resin inside the pipe by translation; a2) Position the calibration sleeve (14) impregnated with curable resin inside the tubular sleeve (10) inside the pipe by flipping it over; b) Curing the curable resin; The wall of the tubular sheath (10) comprises a stack of layers, which, before installation, from the inside out, are: layer B-layer C; layer A-layer B-layer C; layer B-layer A-layer C; layer B-layer A-layer B-layer C; layer A-layer B-layer A-layer B-layer C; or, layer A-layer B-layer A-layer C; and the wall of the calibration sheath (10) comprises layer C (13.a) before installation or comprises a stack of layers A-layer C from the inside out before installation; or - The method in the fourth variant includes the following steps: a) Position the tubular sheath (10) impregnated with curable resin inside the pipe by flipping or translating; b) Curing the curable resin; The wall of the tubular sheath (10) includes stacked layers, which, before installation, are from the inside out: layer C-layer B-layer C; layer C-layer A-layer B-layer C; layer C-layer B-layer A-layer C; layer C-layer A-layer B-layer A-layer B-layer C; or, layer C-layer A-layer B-layer A-layer C; - Layer A (11, 13.b, 14.b) each time it appears independently represents a layer comprising k sheets of woven or nonwoven fibers, the woven or nonwoven fibers including synthetic fibers, natural fibers or mineral fibers or mixtures thereof, where k is an integer from 1 to 20; - Layer B (12) each time it appears independently represents a layer comprising n sheets of synthetic, natural or mineral woven or nonwoven fibers or mixtures thereof, layer B (12) comprising at least 30% by weight of fibers oriented radially in the tubular sheath, preferably at least 70% by weight of fibers oriented radially in the tubular sheath, more preferably 100% by weight of fibers oriented radially in the tubular sheath, the fibers being referred to as reinforcing fibers, wherein the reinforcing fibers are selected from the following fibers: polyester fibers, polyamide fibers, acrylic fibers, phenolic fibers, aramid fibers, glass fibers, carbon fibers, ceramic fibers, basalt fibers, flax fibers, hemp fibers or mixtures of two or more of these types of fibers, and / or, the reinforcing fibers are selected from fibers with a toughness of 30 cN / tex to 500 cN / tex, where n is an integer from 1 to 20; - Layer C (13.a, 14.a) each time it appears independently represents a fluid-sealed layer with a temperature resistance of at least 60°C, the fluid-sealed layer comprising or consisting of a polymer selected from the following polymers: polyurethane, polyethylene, ethylene-propylene-diene polymer (EPDM), silicone, polypropylene, polyimide, polyetheretherketone (PEEK), polybenzimidazole or mixtures thereof.

2. The modification method according to claim 1, wherein, Each layer A (11, 13.b, 14.b) or each layer A (11, 13.b, 14.b) independently comprises k layers of woven or nonwoven fibers each time it appears, where k is an integer from 1 to 20. The woven or nonwoven fibers include synthetic fibers, natural fibers, or mineral fibers or combinations thereof selected from the following fibers: polyester fibers, polyamide fibers, acrylic fibers, phenolic fibers, aramid fibers, glass fibers, carbon fibers, ceramic fibers, basalt fibers, flax fibers, hemp fibers, and mixtures of two or more fibers of these types.

3. The method for modifying a pipeline according to any one of the preceding claims, wherein, Each fluid-sealed layer C (13.a, 14.a) or each fluid-sealed layer C (13.a, 14.a) independently withstands temperatures ranging from 60°C to 200°C each time it occurs; preferably, each fluid-sealed layer C (13.a, 14.a) independently and continuously withstands temperatures of 150°C each time it occurs; and / or, each fluid-sealed layer C (13.a, 14.a) independently withstands peak temperatures of 180°C, 190°C, 200°C, 300°C and / or 400°C each time it occurs; and / or, each fluid-sealed layer C (13.a, 14.a) independently withstands pH values ​​ranging from 1 to 14 each time it occurs.

4. The method for modifying a pipeline according to any one of the preceding claims, wherein, Each layer A (11, 13.b, 14.b) or each layer A (11, 13.b, 14.b) independently comprises 20% to 80% by weight of reinforcing fibers each time it appears, preferably, each layer A (11, 13.b, 14.b) or each layer A (11, 13.b, 14.b) independently comprises 25% to 50% by weight of reinforcing fibers each time it appears, more preferably, each layer A (11, 13.b, 14.b) or each layer A (11, 13.b, 14.b) independently comprises 30% by weight of reinforcing fibers each time it appears.

5. The method for modifying a pipeline according to any one of the preceding claims, wherein, Each layer B (12) or each layer B (12) independently comprises fibers having a toughness of 30 cN / tex to 500 cN / tex each time it appears, preferably, each layer B (12) or each layer B (12) independently comprises fibers having a toughness of 150 cN / tex to 250 cN / tex each time it appears.

6. The method for modifying a pipeline according to any one of the preceding claims, wherein, The composite formed from the layer B (12) having the curable resin or the reinforcing fibers of each layer B (12) has an independent flexural modulus of 2,000 MPa to 50,000 MPa each time it is formed, preferably, the composite formed from the layer B (12) having the curable resin or the reinforcing fibers of each layer B (12) has an independent flexural modulus of 5,000 MPa to 10,000 MPa each time it is formed, more preferably, the composite formed from the layer B (12) having the curable resin or the reinforcing fibers of each layer B (12) has an independent flexural modulus of 7,500 MPa to 20,000 MPa each time it is formed.

7. The method for modifying a pipeline according to any one of the preceding claims, wherein, The curable resin comprises polymers selected from the following or is composed of polymers selected from the following: epoxides, polyesters, vinyl esters, silicone, polyimides, polyamides, silicates, polybenzimidazoles, polymethyl methacrylates, furans, PEEK, and TPU; preferably, the curable resin comprises polymers selected from the following or is composed of polymers selected from the following: epoxy resins and vinyl esters.

8. The method for modifying a pipeline according to any one of the preceding claims, wherein, The curable resin is cured using heat, with the heat source selected from water vapor, hot water, and / or infrared radiation.

9. The method for modifying a pipeline according to any one of the preceding claims, wherein, The curable resin is cured at room temperature.

10. The method for modifying a pipeline according to any one of claims 1 to 8, wherein, The curable resin is cured by electromagnetic radiation, for example, by ultraviolet radiation, microwave radiation or ultrasonic radiation.

11. The method for modifying a pipeline according to any one of the preceding claims, wherein, The lining has a thickness between 1.5 mm and 30 mm before curing; preferably, the lining has a thickness between 1.75 mm and 25 mm before curing; more preferably, the lining has a thickness between 2.0 mm and 20 mm before curing; and / or wherein, The reduction in the inner diameter of the modified pipe is 1% to 20% of the initial diameter, preferably 1% to 8% of the initial diameter, and more preferably 3% of the initial diameter.

12. The method for modifying a pipeline according to any one of the preceding claims, wherein, Each layer C (13.a, 14.a) or each layer C (13.a, 14.a) is independently mechanically bonded to the adjacent layer each time it appears. Preferably, each layer C (13.a, 14.a) or each layer C (13.a, 14.a) is independently bonded to the adjacent layer by extrusion each time it appears.

13. A retrofit kit for metal pipes, the retrofit kit comprising at least one tubular sheath (10) and a curable resin, wherein, The wall of the tubular sheath comprises stacked layers, which, before installation, are arranged from the inside out as follows: layer B-layer C; layer A-layer B-layer C; layer B-layer A-layer C; layer B-layer A-layer B-layer C; layer A-layer B-layer A-layer B-layer C; or, layer A-layer B-layer A-layer C. Each occurrence of layer A (11, 13.b, 14.b) independently represents a layer comprising k sheets of woven or nonwoven fibers, wherein the woven or nonwoven fibers include synthetic fibers, natural fibers, or mineral fibers or mixtures thereof, and k is an integer from 1 to 20; - Layer B (12) each time it appears independently represents a layer comprising n sheets of synthetic, natural or mineral woven or nonwoven fibers or mixtures thereof, wherein layer B (12) comprises at least 30% by weight of fibers oriented radially to the tubular sheath, preferably at least 70% by weight of fibers oriented radially to the tubular sheath, and even more preferably 100% by weight of fibers oriented radially to the tubular sheath, the fibers being referred to as reinforcing fibers, wherein the reinforcing fibers are selected from the following fibers: polyester fibers, polyamide fibers, acrylic fibers, phenolic fibers, aramid fibers, glass fibers, carbon fibers, ceramic fibers, basalt fibers, flax fibers, hemp fibers or mixtures of two or more of these types of fibers, and / or, the reinforcing fibers are selected from fibers with a toughness of 30 cN / tex to 500 cN / tex, where n is an integer from 1 to 20; Layer C (13.a, 14.a) each time it appears independently represents a fluid-sealed layer with a temperature resistance of at least 60°C, the fluid-sealed layer comprising or consisting of a polymer selected from the following polymers: polyurethane, polyethylene, ethylene-propylene-diene polymer (EPDM), silicone, polypropylene, polyimide, polyether ether ketone (PEEK), polybenzimidazole or mixtures thereof.

14. The modification kit according to claim 13, further comprising a calibration sleeve (14), wherein, The wall of the calibration sheath includes layer C (13.a, 14.a) before installation or a stack of layers A-C from the inside out before installation.

15. The modification kit according to claim 13, wherein, The wall of the tubular sheath comprises stacked layers, which, before installation, are arranged from the inside out as follows: layer C-layer B-layer C; layer C-layer A-layer B-layer C; layer C-layer B-layer A-layer C. It can be layer C-layer A-layer B-layer A-layer B-layer C; or, it can be layer C-layer A-layer B-layer A-layer C.

16. The modification kit according to any one of claims 13 to 15, wherein, Each layer A (11, 13.b, 14.b) or each layer A (11, 13.b, 14.b) independently comprises k layers of woven or nonwoven fibers each time it appears, where k is an integer from 1 to 20. The woven or nonwoven fibers include synthetic fibers, natural fibers, or mineral fibers or combinations thereof selected from the following fibers: polyester fibers, polyamide fibers, acrylic fibers, phenolic fibers, aramid fibers, glass fibers, carbon fibers, ceramic fibers, basalt fibers, flax fibers, hemp fibers, and mixtures of two or more fibers of these types.

17. The modification kit according to any one of claims 13 and 14, wherein, Each layer B (12) or each layer B (12) independently comprises fibers having a toughness of 30 cN / tex to 500 cN / tex each time it appears, preferably, each layer B (12) or each layer B (12) independently comprises fibers having a toughness of 150 cN / tex to 250 cN / tex each time it appears.

18. The modification kit according to any one of claims 13 to 17, wherein, The composite formed from the layer B (12) having the curable resin or the reinforcing fibers of each layer B (12) has an independent flexural modulus of 2,000 MPa to 50,000 MPa each time it is formed, preferably, the composite formed from the layer B (12) having the curable resin or the reinforcing fibers of each layer B (12) has an independent flexural modulus of 5,000 MPa to 10,000 MPa each time it is formed, more preferably, the composite formed from the layer B (12) having the curable resin or the reinforcing fibers of each layer B (12) has an independent flexural modulus of 7,500 MPa to 20,000 MPa each time it is formed.

19. The modification kit according to any one of claims 13 to 18, wherein, Each fluid-sealed layer C (13.a, 14.a) or each fluid-sealed layer C (13.a, 14.a) independently withstands temperatures ranging from 60°C to 200°C each time it occurs; preferably, each fluid-sealed layer C (13.a, 14.a) independently and continuously withstands temperatures of 150°C each time it occurs; and / or, each fluid-sealed layer C (13.a, 14.a) independently withstands peak temperatures of 180°C, 190°C, 200°C, 300°C and / or 400°C each time it occurs; and / or, each fluid-sealed layer C (13.a, 14.a) independently withstands pH values ​​ranging from 1 to 14 each time it occurs.

20. The modification kit according to any one of claims 13 to 19, wherein, Each layer A (11, 13.b, 14.b) or each layer A (11, 13.b, 14.b) independently comprises 20% to 80% by weight of reinforcing fibers each time it appears, preferably, each layer A (11, 13.b, 14.b) or each layer A (11, 13.b, 14.b) independently comprises 25% to 50% by weight of reinforcing fibers each time it appears, more preferably, each layer A (11, 13.b, 14.b) or each layer A (11, 13.b, 14.b) independently comprises 30% by weight of reinforcing fibers each time it appears.

21. The modification kit according to any one of claims 13 to 20, wherein, The curable resin comprises polymers selected from the following or is composed of polymers selected from the following: epoxides, polyesters, vinyl esters, silicone, polyimides, polyamides, silicates, polybenzimidazoles, polymethyl methacrylates, furans, PEEK, and TPU; preferably, the curable resin comprises polymers selected from the following or is composed of polymers selected from the following: epoxy resins and vinyl esters.

22. The modification kit according to any one of claims 13 to 21, wherein, The tubular sheath (10) has a thickness between 1.5 mm and 30 mm before curing, and / or the calibration sheath (14) together with the curable resin has a thickness between 1.5 mm and 30 mm before curing. Preferably, the tubular sheath (10) has a thickness between 1.75 mm and 25 mm before curing, and / or the calibration sheath (14) together with the curable resin has a thickness between 1.75 mm and 25 mm before curing. More preferably, the tubular sheath (10) has a thickness between 2.0 mm and 20 mm before curing, and / or the calibration sheath (14) together with the curable resin has a thickness between 2.0 mm and 20 mm before curing.

23. The modification kit according to any one of claims 13 to 22, wherein, One or more of the layers C (13.a, 14.a) are mechanically bonded to adjacent layers, preferably, one or more of the layers C (13.a, 14.a) are bonded to adjacent layers by extrusion.

24. A modified metal pipe, said modified metal pipe comprising a hardened lining, wherein, The wall of the cured lining comprises a stack of layers, the layers from the outside to the inside being: layer B-layer C; layer A-layer B-layer C; layer B-layer A-layer C; For layer B-layer A-layer B-layer C; For layer A-layer B-layer A-layer B-layer C; For layer A-layer B-layer A-layer C; For layer C-layer B-layer C; For layer C-layer A-layer B-layer C; For layer C-layer B-layer A-layer C; For layer C-layer B-layer A-layer B-layer C; For layer C-layer B-layer A-layer B-layer A-layer C; The layers are: C-A-B-A-B-C; The layers are: C-A-B-A-C; The layers are: C-A-B-C; The layers are: C-B-A-A-C; It can be layer C-layer B-layer A-layer B-layer A-layer A-layer C; or, it can be layer C-layer A-layer B-layer A-layer A-layer C. Each occurrence of layer A (11, 13.b, 14.b) independently represents a layer comprising k sheets of woven or nonwoven fibers, wherein the woven or nonwoven fibers include synthetic fibers, natural fibers, or mineral fibers or mixtures thereof, and k is an integer from 1 to 20; - Layer B (12) each time it appears independently represents a layer comprising n sheets of synthetic, natural or mineral woven or nonwoven fibers or mixtures thereof, layer B (12) comprising at least 30% by weight of fibers oriented radially in the tubular sheath, preferably at least 70% by weight of fibers oriented radially in the tubular sheath, and even more preferably 100% by weight of fibers oriented radially in the tubular sheath, the fibers being referred to as reinforcing fibers, wherein the reinforcing fibers are selected from the following fibers: polyester fibers, polyamide fibers, acrylic fibers, phenolic fibers, aramid fibers, glass fibers, carbon fibers, ceramic fibers, basalt fibers, flax fibers, hemp fibers or mixtures of two or more of these types of fibers, and / or, the reinforcing fibers are selected from fibers with a toughness of 30 cN / tex to 500 cN / tex, where n is an integer from 1 to 20; Layer C (13.a, 14.a) each time it appears independently represents a fluid-sealed layer with a temperature resistance of at least 60°C, the fluid-sealed layer comprising or consisting of a polymer selected from the following polymers: polyurethane, polyethylene, ethylene-propylene-diene polymer (EPDM), silicone, polypropylene, polyimide, polyether ether ketone (PEEK), polybenzimidazole or mixtures thereof.

25. The modified metal pipe according to claim 24, wherein, Each layer A (11, 13.b, 14.b) or each layer A (11, 13.b, 14.b) independently comprises k layers of woven or nonwoven fibers each time it appears, where k is an integer from 1 to 20. The woven or nonwoven fibers include synthetic fibers, natural fibers, or mineral fibers or combinations thereof selected from the following fibers: polyester fibers, polyamide fibers, acrylic fibers, phenolic fibers, aramid fibers, glass fibers, carbon fibers, ceramic fibers, basalt fibers, flax fibers, hemp fibers, and mixtures of two or more fibers of these types.

26. The modified metal pipe according to any one of claim 24 or 25, wherein, Each layer B (12) or each layer B (12) independently comprises fibers having a toughness of 30 cN / tex to 500 cN / tex each time it appears, preferably, each layer B (12) or each layer B (12) independently comprises fibers having a toughness of 150 cN / tex to 250 cN / tex each time it appears.

27. The modified metal pipe according to any one of claims 24 to 26, wherein, The composite formed from the layer B (12) having the curable resin or the reinforcing fibers of each layer B (12) has an independent flexural modulus of 2,000 MPa to 50,000 MPa each time it is formed, preferably, the composite formed from the layer B (12) having the curable resin or the reinforcing fibers of each layer B (12) has an independent flexural modulus of 5,000 MPa to 10,000 MPa each time it is formed, more preferably, the composite formed from the layer B (12) having the curable resin or the reinforcing fibers of each layer B (12) has an independent flexural modulus of 7,500 MPa to 20,000 MPa each time it is formed.

28. The modified metal pipe according to any one of claims 24 or 27, wherein, Each fluid-sealed layer C (13.a, 14.a) or each fluid-sealed layer C (13.a, 14.a) independently withstands temperatures ranging from 60°C to 200°C each time it occurs; preferably, each fluid-sealed layer C (13.a, 14.a) independently and continuously withstands temperatures of 150°C each time it occurs; and / or, each fluid-sealed layer C (13.a, 14.a) independently withstands peak temperatures of 180°C, 190°C, 200°C, 300°C and / or 400°C each time it occurs; and / or, each fluid-sealed layer C (13.a, 14.a) independently withstands pH values ​​ranging from 1 to 14 each time it occurs.

29. The modified metal pipe according to any one of claims 24 to 28, wherein, Each layer A (11, 13.b, 14.b) or each layer A (11, 13.b, 14.b) independently comprises 20% to 80% by weight of reinforcing fibers each time it appears, preferably, each layer A (11, 13.b, 14.b) or each layer A (11, 13.b, 14.b) independently comprises 25% to 50% by weight of reinforcing fibers each time it appears, more preferably, each layer A (11, 13.b, 14.b) or each layer A (11, 13.b, 14.b) independently comprises 30% by weight of reinforcing fibers each time it appears.

30. The modified metal pipe according to any one of claims 24 to 29, wherein, The curable resin comprises polymers selected from the following or is composed of polymers selected from the following: epoxides, polyesters, vinyl esters, silicone, polyimides, polyamides, silicates, polybenzimidazoles, polymethyl methacrylates, furans, PEEK, and TPU; preferably, the curable resin comprises polymers selected from the following or is composed of polymers selected from the following: epoxy resins and vinyl esters.

31. The modified metal pipe according to any one of claims 24 to 30, wherein, The reduction in the inner diameter of the modified pipe is 1% to 20% of the initial diameter of the pipe. Preferably, the reduction in the inner diameter of the modified pipe is 1% to 8% of the initial diameter of the pipe. More preferably, the reduction in the inner diameter of the modified pipe is 3% of the initial diameter of the pipe.

32. The use of the retrofit kit according to any one of claims 13 to 23 for the internal coating retrofit of metal pipes, particularly, said metal pipes being zone heating pipes, wastewater treatment pipes in the paper and / or chemical industries, offshore platform pipes, smelting pipes, or brewery pipes.

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