BE1031815B1 - Structuring and temperature-resistant sheath for sheathing pipelines - Google Patents

Abstract

A method of renovating a water pipe, in particular a district heating pipe, by installing a jacket inside the pipe, wherein said jacket comprises at least one tubular sheath impregnated with a hardenable resin or one tubular sheath and one calibration sheath impregnated with a hardenable resin.

Description

STRUCTURING AND TEMPERATURE RESISTANT SHEATH FOR THE

PIPELINE LINERS

Technical field

[0001] The present invention relates to a method for renovating a metal pipe, in particular a district heating pipe, which comprises a jacket comprising a tubular sheath or a tubular and calibration sheath. Another aspect of the invention relates to a kit for renovating a metal pipe and its use as well as a renovated metal pipe.

State of the art

[0002] Metal pipes, and more particularly district heating pipes, are often buried and insulated and can be quickly damaged due to the combination of a hot and humid environment which promotes the corrosion of metal pipes. When these are damaged, their repair or replacement generally requires work that can be long and costly. Replacing a pipe, for example, may require opening a trench to install a new pipe. In addition to the significant costs, this work generally generates many inconveniences, such as road closures, noise pollution and prolonged network outage. In addition, only short sections can be replaced in a single step. In addition to renovating district heating pipes, there is a need to improve the thermal insulation of district heating pipes.

Subject of the invention

[0003] An object of the present invention is therefore to provide an easy-to-implement, rapid and inexpensive method for renovating metal pipes, more particularly district heating pipes. In particular for district heating pipes, the method should make it possible to form a coating capable of simultaneously renovating and improving the thermal insulation of these pipes. Another object of the invention is to provide a renovation kit to be able to easily implement such a method.

General description of the invention

[0004] In order to solve the problem mentioned above, the present invention proposes, in a first aspect, a method for renovating a metal pipe, by installing a jacket inside the pipe, in which said jacket comprises at least one tubular sheath impregnated with a curable resin or a tubular sheath and a calibration sheath impregnated with a curable resin, in which - the method comprises in a first variant the steps: a) positioning in the pipe said tubular sheath impregnated with a curable resin by reversion; b) curing the curable resin; the wall of the tubular sheath comprising, before installation from the inside to the outside, a stack of layers B-C, A-B-C, B-A-C, B-A-B-C, A-B-A-

B-C or A-B-A-C; or - the method comprises in a second variant the steps: a1) positioning in the pipe a layer C by reversion or by translation; a) positioning in the pipe, inside the layer C, said tubular sheath impregnated with a resin curable by reversion; b) curing the curable resin; the wall of the tubular sheath comprising, before installation from the inside to the outside, a stack of layers B-C, A-B-C, B-A-C, B-A-B-C, A-B-A-

B-C or A-B-A-C; or - the method comprises in a third variant the steps: a) positioning in the conduit said tubular sheath impregnated with a resin curable by translation; a2) positioning in the conduit, inside the tubular sheath, said calibration sheath impregnated with resin curable by reversion; b) curing the curable resin;

the wall of said tubular sheath comprising, before installation from the inside to the outside, a stack of layers B-C, A-B-C, B-A-C, B-A-B-C, A-B-

A-B-C or A-B-A-C and the wall of said calibration sheath comprising, before installation, a layer C or from the inside to the outside a stack of layers A-C; or - the method comprises in a fourth variant the steps: a) positioning in the conduit said tubular sheath impregnated with a resin curable by reversion or by translation; b) curing the curable resin; the wall of the tubular sheath comprising, before installation from the inside to the outside, a stack of layers C-B-C, C-A-B-C, C-B-A-C, C-A-B-A-B-C or C-A-B-A-C; - A representing independently at each occurrence a layer comprising a number k of plies of woven or non-woven fibers comprising synthetic, natural or mineral fibers, or a mixture thereof, k being an integer from 1 to 20; - B representing independently at each occurrence a layer comprising a number n of strata of synthetic, natural or mineral woven or non-woven fibers, or a mixture thereof, comprising at least 30%, preferably at least 70%, more preferably 100% by weight of the fibers oriented in the radial direction of the tubular sheath, called reinforcing fibers, in which the reinforcing fibers are chosen from polyester, polyamide, acrylic, phenolic, aramid fibers, glass, carbon, ceramic, basalt, linen, hemp fibers or mixtures of two or more of these types of fibers, and/or from fibers having a tenacity of 30 to 500 cN/tex, n being an integer from 1 to 20; - C representing independently at each occurrence a fluid-tight layer resistant to temperatures of at least 60°C, comprising or consisting of polymers chosen from polyurethanes, polyethylenes, ethylene-propylene-diene polymers (EPDM), silicones, polypropylenes, polyimides, polyetheretherketones (PEEK), polybenzimidazoles or mixtures thereof.

[0005] The present invention relates to a method for renovating metal pipes, more particularly metal pipes for urban heating, effluent treatment in the paper industry and/or in the chemical industry, offshore platforms, refineries, breweries, etc.

[0006] The proposed method for renovating the pipeline has the advantage of being able to be used either by a reversal insertion method or by a translation insertion method. The choice of the particular variant of the method will be influenced for example by the configuration of the pipeline to be renovated and the requirements that it must meet, namely the diameter, the length, the presence of curves or changes in direction, the pressure, the temperature of the fluid inside the pipeline, etc.

[0007] In the context of the present invention, the term “liner” represents the tubular sheath, or the tubular sheath and the calibration sheath, impregnated with a resin and positioned in the metal pipe to be renovated.

[0008] The term “layer” of the present invention represents a sheet of woven or non-woven fibers. The layers can be superimposed on each other forming an assembly called a “layer”. The term “layer” of the present invention generally represents an assembly comprising or consisting of one or more layers of woven or non-woven fibers, a layer being able to comprise from 1 to 20 layers, preferably from 1 to 5 layers. 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 layers. The term layer can also designate a layer being composed of polymers, the layer can in this case be called a waterproof and temperature-resistant layer or simply a waterproof layer. Depending on the context, a layer according to the present invention may therefore represent a set consisting of strata(s) of woven or non-woven fibers, in this case the layers

A and/or B, or a polymer layer, in this case layer(s) C.

[0009] In the present context, the term "position" means that the liner is, in a first step, inserted and installed in the pipe either in one step of insertion by reversion or by translation, or in two steps of insertion by translation of a tubular sheath followed by the insertion of a calibration sheath by reversion, or in two steps of insertion of a waterproof layer by reversion or by translation of a tubular sheath (layer C) followed by the insertion by reversion of a calibration sheath, then, after insertion, said liner is inflated so that it approaches the walls of the pipe in order to adjust to the pipe to be renovated. Once the liner is positioned (step a) or step a1) then a), or a) then a2)), i.e. installed and inflated, the curable resin is hardened (step b)) so as to form a hard/solid liner, of stable shape and capable of withstanding the pressure conditions (internal, external loads) and temperature when the renovated metal pipe is put into service.

[0010] A reversal insertion means that the liner is allowed to advance into the pipe while being inverted/reversed. A reversal insertion implies that the layer on the outer part of the liner before positioning, becomes the layer on the inner part of the liner after installation, i.e. after reversal. In a reversal insertion, the liner is allowed to advance under the effect of a positive air or water pressure.

A translational insertion means that the sheath is pulled inside the pipe, in a translational movement and without reversing the initial order (before installation) of the layers in the internal direction towards the exterior.

[0011] Said jacket advantageously comprises a tubular sheath which comprises a set of layers B and C, or a set of layers A, B and

C. Layer A comprising one or more layers of woven or non-woven fibers comprising synthetic, natural, mineral fibers or a mixture thereof, layer B comprising one or more layers of woven or non-woven fibers comprising reinforcing fibers or also called high-performance fibers, and the waterproof layer C comprising polymers and located on the outer part of the tubular sheath before installation. Layer C will therefore necessarily always be positioned on the outer part of the tubular sheath before installation, that is to say that the waterproof layer C will always be positioned on the outer surface of the tubular sheath before installation. When said jacket is installed according to the fourth variant of the method, the tubular sheath further comprises a layer C located in the inner part of the tubular sheath before installation, that is to say on the inner surface of the tubular sheath before installation. In other words, in the case of variant 4, a layer C will be positioned both on the outer part of the tubular sheath before installation and on the inner part. Advantageously, the tubular sheath may comprise several layers A and/or several layers B which are superimposed on each other alternately, forming a set of layers from the inside to the outside of the tubular sheath before installation A-B, A-B-A, A-B-A-

B, B-A, B-A-B, B-A-B-A, the tubular sheath always comprising on the external surface of its wall before installation a waterproof layer C. The waterproof layer

C polymer may be mechanically or non-mechanically bonded to layer A or

B adjacent.

[0012] When the jacket is installed according to the first variant of the method, i.e. according to a positioning by reversion of the tubular sheath, the layers are reversed and the jacket then comprises a set of layers B and C or a set of layers A, B and C, said layer C being positioned on the inner face of said jacket. Once positioned, layer A or layer B will be against the wall of the pipe, while layer C will be located in the internal part, thus finding itself positioned to be in contact with the fluid in the renovated pipe.

[0013] When the tubular sheath is positioned according to the third variant of the method, i.e. by translation in step a) of the method, a step a2), which comprises the installation of a calibration sheath by reversion in the tubular sheath, is provided. In this configuration, the layer C of the tubular sheath will be located, after installation, on the external part of the jacket, said sealed layer C then being in contact with the pipe, while the calibration sheath will be in the internal part of the jacket, the sealed layer C of said calibration sheath being on the internal face, positioned to be in contact with the fluid in the renovated pipe, the tubular sheath and the pipe thus being isolated and protected from the (high temperature) fluid in circulation.

[0014] The liner will have a certain flexibility and suppleness to allow its insertion into the pipe, in particular during the reversion step, that is to say when the liner is inserted by turning over into the pipe, as well as during the swelling step.

[0015] Depending on the configuration of the pipe, the person skilled in the art will choose to position the jacket according to one of the variants of the method, either by reversion or by translation then reversion. In the case of a pipe that includes “elbows”, or changes in direction, the first variant of the method, i.e. the reversed version (according to step a)), will be preferred to the third variant of the method, i.e. the translated then reversed version (according to step a) then a2)). When the distance between two access points of the pipe is large, the jacket will be installed preferentially according to the third variant of the method, according to steps a) and a2).

[0016] In the context of the present invention, the expression "impregnated with curable resin" means that all of the impregnable layers, therefore with the exception of the waterproof layer(s) C, forming the tubular and calibration sheaths are saturated with a curable resin, the impregnation of the tubular and calibration sheaths generally being carried out before the installation of the jacket in the pipe. After impregnation, the resin is found inside the sheath, and, advantageously, the waterproof layer located outside the tubular and/or calibration sheaths prevents the resin from flowing before the sheaths are positioned in the pipe.

[0017] When the tubular sheath is installed by reversion, the resin-impregnated layers will end up against the pipe wall during the reversion process. In this configuration, the jacket may, if necessary, stick to the wall during the curing step.

[0018] When the tubular sheath is installed by translation, then the calibration sheath is installed by reversion (according to the third variant of the method, step a) then a2)), the waterproof layer C of the tubular sheath will be against the wall, and the resin will not in principle stick to the wall of the pipe after hardening. This configuration can allow better resistance to movements of the pipe which could be due to external factors, such as ground movement, earthquakes, etc., or to expansion effects of the pipe due to the conditions of use of the pipe such as temperature variations.

[0019] When positioning according to the third variant of the method is not possible, in particular because of constraints linked to the size and/or shape of the pipe to be renovated, the person skilled in the art may choose to install, before step a), by a step a1), a waterproof layer C. Step a1) may be carried out by reversing or by pulling said layer C into the pipe. After installation of the layer

C in the conduit, the tubular sheath is installed following step a), said layer

C is therefore between the pipe and the tubular sheath, thus acting as a protective and waterproof layer. Advantageously, once installed according to step a1) followed by step a) (second variant of the process), the liner will not stick directly to the wall and will therefore be more resistant to size variations by expansion/contraction of the metal pipe which could be due to temperature variations during commissioning and during use of the metal pipe. The liner thus positioned will not stick to the metal pipe after swelling, and will therefore be less likely to break or become fragile depending on external conditions.

[0020] The person skilled in the art may also choose to install the jacket according to a fourth variant of the method. In this variant, the tubular sheath which comprises two sealed layers surrounding all of the layers A-B or B, may be positioned in the pipe by reversion or by traction.

Advantageously, the tubular sheath once installed will comprise a waterproof C layer directly against the wall and a waterproof C layer on the inner surface of the jacket directly in contact with the fluid. The jacket thus positioned will not stick to the wall and will be protected from the fluid by the presence of the internal C layer.

[0021] The jacket proposed for renovating and reinforcing the pipe also has resistance to tearing and abrasion, in particular during the positioning step. Indeed, during insertion by reversion or translation into the pipe to be renovated, said jacket must be resistant to roughness and defects in the inner part of the pipe, such as corrosion, but it must also be resistant to piercing during the swelling step or it will approach under air pressure against the wall.

[0022] After the resin hardens, the liner becomes hard, shape stable and sufficiently resistant to the internal pressure exerted by the passage of the fluid and the liner must allow the passage of the fluid efficiently.

[0023] According to a preferred embodiment, layer A comprises a number k of plies of woven or non-woven fibers comprising synthetic, natural, mineral fibers or a mixture thereof, k being an integer from 1 to 20, preferably 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 plies. The synthetic fibers are preferably chosen from polyester, polyamide, acrylic, phenolic, aramid fibers or their mixtures. The mineral fibers are preferably chosen from glass, carbon, ceramic, basalt, etc. fibers, or their mixtures. The natural fibers are preferably chosen from flax, hemp, etc. fibers or their mixtures. Preferably, layer A comprises one, two, three, four or five layers of woven or non-woven fibers chosen from polyester, polyamide, acrylic fibers, natural or recycled linen fibers or a mixture thereof.

[0024] According to another preferred embodiment, layer B comprises a number n of plies of synthetic, natural or mineral woven or non-woven fibers, or a mixture thereof comprising at least 30%, preferably at least 70%, more preferably 100% by weight of the fibers oriented in the radial direction of the tubular sheath, called reinforcing fibers, in which the reinforcing fibers are chosen from polyester, polyamide, acrylic, phenolic, aramid fibers, glass, carbon, ceramic, basalt, linen, hemp fibers or mixtures of two or more of these types of fibers, and/or from fibers having a tenacity of about 30 to about 500 cN/tex, n being an integer from 1 to 20. Preferably, layer B comprises a number n of plies of synthetic, natural or mineral woven or non-woven fibers, or a mixture thereof comprising at least 30%, preferably at least 70%, more preferably 100% by weight of the fibers oriented in the radial direction of the tubular sheath, called reinforcing fibers, in which the reinforcing fibers are chosen from polyester, polyamide, acrylic, phenolic, aramid fibers, glass, carbon, ceramic, basalt, linen, hemp fibers or mixtures of two or more of these types of fibers, and/or from fibers having a tenacity of about 30 to about 500 cN/tex, n being an integer from 1 to 20.

B comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 layers. In the context of the present invention, the reinforcing fibers are fibers having a high tensile strength and resistance to deformation under pressure, making it possible to reinforce the tubular sheath and prevent it from deteriorating under the effect of pressure. The reinforcing fibers according to the invention are fibers which give layer B good resistance to deformation caused by pressure. The resistance to pressure can be characterized by the toughness of the material, i.e. its ability to resist the propagation of a crack. The toughness of a fiber or textile is defined by the elastic limit of a material, i.e. by the force in centiNewton/tex (cN/tex) that it is able to withstand and then return to its initial shape without deformation. The toughness is measured with a dynamometer. The reinforcing fibers that form layer B will have a toughness value of approximately 150 cN/tex, preferably approximately 250 cN/tex. The resistance to pressure is also defined by the flexural modulus. The flexural modulus represents the pressure to be applied to deform the tube, and is expressed in

MPa. The resin-impregnated layer B, i.e. the composite material comprising the woven or non-woven reinforcing fibers of layer B and the curable resin, will have a flexural modulus of about 2000 to about 50,000 MPa, preferably about 5,000 to about 10,000 MPa, more preferably about 7,500 to about 20,000 MPa. Layer B is generally composed of one or more plies of reinforcing fibers, depending on the pressure constraints inherent in the pipe to be renovated. The fibers composing layer B will be chosen from glass fibers, carbon fibers or their mixtures having a high pressure resistance. Layer B will generally be composed of at least 30%, preferably at least 70% by weight of reinforcing fibers, more preferably at least 100% by weight of reinforcing fibers. In order to ensure its correct positioning and to improve the mechanical properties of the tubular sheath, layer B is generally positioned between two layers, for example between layer A and the sealed layer C, or between two layers A, or between two sealed layers C. More particularly, in the case of small-diameter pipes, layer B will preferably be composed of a combination of a non-woven glass fiber layer and a woven glass fiber layer. Preferably, layer B comprises one, two, three, four or five layers of woven or non-woven reinforcing fibers, the fibers preferably being woven or non-woven glass fibers. Layer A of the tubular sheath and layer A of the calibration sheath may comprise independently at each occurrence from 20 to 80% by weight of reinforcing fibers, in particular from 25 to 50% by weight of reinforcing fibers, preferably approximately % by weight of reinforcing fibers. 30 [0025] The inventors observed, unexpectedly, that layer B composed of reinforcing fibers, has a double advantage. On the one hand, the layer

B allows the sheath to be reinforced by making it more resistant to pressure and thus reinforces its mechanical properties while reducing the number of layers of woven or non-woven fibers (layers A) that would have been necessary to achieve the same pressure resistance properties in the absence of high-performance fibers. On the other hand, the presence of layer B therefore allows, for the same mechanical efficiency, to reduce the thickness of the jacket, inducing a reduction in the number of layers and therefore a reduction in the manufacturing cost, as well as a reduction in the quantity of resin necessary to impregnate the tubular sheath and, where applicable, the calibration sheath. The reduction in the thickness of the jacket facilitates its installation in the pipe to be renovated, the internal diameter of the renovated pipe will be less reduced, therefore making it possible to limit a drop in fluid flow rate after renovation which could be due to a reduction in the useful diameter of the pipe after renovation.

[0026] According to the invention, layer C comprises or consists of a fluid-tight layer that is resistant to temperature and chemicals. The waterproof layer is a polymer layer, the polymers of which are preferably chosen from polyurethanes, polyethylenes, ethylene-propylene-diene polymers (EPDM), silicones, polypropylenes, polyimides, polyetheretherketones (PEEK), polybenzimidazoles or mixtures thereof. This waterproof layer C may be mechanically or non-mechanically bonded (for example by extrusion, sprinkling or bonding) to the layer(s) of woven or non-woven fibers of layer A or B adjacent to it. Said waterproof layer C will therefore be found on the internal surface of the jacket, when the tubular sheath is installed by reversion. Said waterproof layer C, makes it possible to isolate the layer(s) A and/or B from the fluid (which may be at high temperature, for example from 60 to 400 °C, or even more) circulating in the pipe, thus making it possible to maintain the initial insulating properties of said layers, to improve and optimize the insulating properties of the pipe by reducing heat losses during the circulation of the fluid (at high temperature) in the renovated pipe. In addition to insulating said layers, the waterproof layer(s) C make it possible to insulate the interior surface of the pipe and to avoid corrosion and wear phenomena due to the passage of the fluid (at high temperature).

[0027] Advantageously, the waterproof layer C is in contact with the fluid circulating in the pipe. The metal pipes to be renovated according to the present invention relate to pipes in which fluids at high temperatures and at different pHs can circulate. Said waterproof layers C will be chosen according to the constraints linked to the fluid. Preferably, said layers

C tight layers are resistant to high temperatures, for example temperatures of approximately 60 to 200 °C continuously, preferably approximately 150 °C continuously, and temperatures of approximately 180, 190, 200, 300 and/or 400 °C as peak temperatures, for example when the renovated metal pipe is put into service. Resistance to a continuous temperature means, in the context of the invention, that the tight layer(s) will be resistant to temperatures of approximately 60 to 200 °C, i.e. they will be resistant to temperatures of the circulating fluid having a constant temperature over time, throughout the entire period of use of the jacket. During the use of the renovated pipe, temperature variations may occur, more particularly temperature peaks of the temporary fluid. For the purposes of the invention, peak temperatures represent the temperatures that the fluid can temporarily reach during use of the renovated pipe.

Advantageously, the sealing layer(s) are resistant to these temperature variations and more particularly to temperatures of approximately 180, 190, 200, 300 and/or 400°C at peak temperature, i.e. the C layers retain their sealing and temperature resistance properties. Preferably, said sealing C layers are resistant to pH values ranging from 1 to 14, the nature of the polymer will be chosen according to the use of the renovated pipe, i.e. according to the nature (physicochemical properties such as pH) and the temperature of the fluid circulating in the pipe.

[0028] One of the advantages of the jacket as described by the invention is its insulating power. All of the layers, A, B and C, make it possible to improve and increase the insulating power of the pipe, by adding successive layers and/or strata which thermally insulate the pipe from the fluid, reducing heat losses and therefore energy losses to transport the fluid at the desired temperature at its point of arrival. Those skilled in the art will be able to adjust the number and thickness of the layers by adjusting the number of fiber strata according to the diameter of the pipe to be renovated and the desired thermal and mechanical insulation properties. One of the advantages of the present invention is to be able to adjust the thickness of the jacket, by adjusting the number of layers and the number of strata according to the constraints related to the renovation of the pipe. Increasing the thickness of the jacket inevitably reduces the internal diameter of the renovated pipe, i.e. the useful section of the renovated pipe. Unexpectedly, this loss of useful section is compensated by the insulating effect of the jacket as well as by the improvement of the mechanical properties of said jacket.

[0029] The jacket will advantageously have a thermal conductivity of 0.0025 to 0.25 W.m".K*, preferably 0.2 W.m".K*. Thermal conductivity represents the capacity of the material to diffuse heat through the material and can be measured by the hot wire method.

Advantageously, the jacket, due to its insulating effect, reduces energy losses by at least 25%, compared to an unrenovated pipe.

[0030] Depending on the constraints related to the commissioning, the size of the pipe and/or thermal insulation, etc., the person skilled in the art may choose to install the jacket according to variant 1, 2, 3 or 4. The positioning according to step a) of the first variant makes it possible to obtain a thermally insulated pipe from layer A and/or B and C, while the sealed layer C in direct contact with the fluid (at high temperature) will isolate the felt layers from the fluid circulating in the pipe. In the case of an installation according to steps a) then a2) of the third variant of the method, the jacket will comprise an external sealed layer C which is located directly in contact with the internal part of the pipe and an internal sealed layer C, which is positioned to be in contact with the fluid (at high temperature). This additional sealed layer C will have the advantage of making it possible to further improve the thermal properties of the jacket.

In fact, the fourth layer allows on the one hand to add additional layers of fibers increasing a priori the thermal insulation effect and improving the mechanical properties, and on the other hand allows to provide a second waterproof layer C which is in direct contact with the internal wall of the renovated pipe.

The layer(s) C have, independently at each occurrence, a thickness of between approximately 0.2 mm and approximately 1.5 mm, preferably a thickness of approximately 0.5 mm. Similar to the positioning by reversion of the tubular sheath, during the positioning according to the third variant, following step a) then a2), a sealed layer C, in this case the sealed layer C of the calibration sheath, is in contact with the fluid (at high temperature) circulating in the pipe, and will therefore have the role of serving as a conduit for the fluid (at high temperature) and preventing it from infiltrating the felt layers of layers A and/or B, which would reduce their insulating power, but in addition, in this case, the tubular sheath being positioned by traction, the sealed layer C of the tubular sheath is in contact with the internal wall of the pipe. This has the advantage of preventing water infiltration from outside the pipe, for example in the case where said pipe is damaged due to external factors. This sealing of the exterior allows the insulating and thermal properties of the jacket to be preserved, even in the event of external deterioration of the pipe. All of the C-layers

B-C or C-A-B-C, or possible combinations when installing according to the third variant of the process, allows increased thermal insulation, even in these cases. Thus, when thermal insulation is an important factor, the positioning according to the third variant of the process, according to step a) then a2) will be preferred.

[0031] Another advantage of the presence of the waterproof layer C in direct contact with the circulating fluid is the generally smooth surface formed by a polymer layer. Indeed, in the case of an unprotected and unrenovated pipe, deposits may occur on the internal wall of the pipe, due for example to corrosion, creating roughness which induces an increasing pressure loss. The presence of a polymer layer not sensitive to corrosion on the internal wall of the liner makes it possible to obtain a generally smooth surface whose surface will change little or not at all over time, maintaining a constant pressure loss over time. Thus, the pressure loss which could result from the reduction in the internal diameter due to the installation of the liner can be compensated by a generally smoother internal surface not subject to corrosion, an advantage which cannot be obtained by insulating the pipe from the outside for example.

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

[0033] The commissioning and use of a metal pipe involves numerous physical and technical constraints such as the possibility of corrosion due to the nature of the fluid, high temperatures and humidity, the presence of water hammer, energy losses and the expansion of the pipe as a function of temperature. Water hammer is an overpressure phenomenon that occurs during sudden changes in the speed of a fluid, for example when opening or closing a valve. The liner and the renovation method must be able to meet its various constraints. Advantageously, the liner and the renovation method of the present invention make it possible to optimize various parameters as a function of the constraints related to the pipe to be renovated. Indeed, the nature and composition of the liner, in particular the composition and number of layers of layers A and B, as well as the number of layers A, B and C of the liner will be determined as a function of the constraints related to the commissioning and use of the renovated pipe. As explained above, the presence of a watertight layer C between the wall and the tubular sheath will prevent the tubular sheath from sticking to the pipe wall and therefore the liner will not follow the movements of the pipe wall. The nature of the polymer of layer C, regardless of whether it is located in the internal part of the liner or both in the internal part of the liner and on the external part of the liner (against the pipe wall), will be determined according to the temperature and pH of the fluid in contact with layer C, as well as according to the possibility of water hammer and energy losses. The number and nature of the layers of layer(s) A will be determined by the possible presence of water hammer and the presence of significant external loads. Adjusting the number of layers A and the number of layers of each layer A allows the final thickness of the liner to be adjusted to compensate for possible air voids and allows the liner to be reinforced against external loads. In addition, adjusting the number of layers

A allows to optimize energy losses by allowing to isolate the fluid pipe and thus to reduce heat exchanges between the inside and the outside of the jacket. The presence of reinforcement layers B, the nature as well as their number and the number of strata of each layer B can be determined according to the pressure in the pipe to be renovated.

[0034] The layer(s) of woven or non-woven fibers of layer(s) A may independently comprise the same materials at each occurrence and may comprise from 20 to 80%, preferably 30% by weight of reinforcing fibers.

[0035] According to one embodiment, the tubular sheath may comprise one or more layers A and B superimposed on each other alternately, the tubular sheath always having a sealed layer C on its outer part before installation. Thus, the tubular sheath may have the configuration, for example, from the inside to the outside before installation, A-B-A-C, or A-B-A-C, or,

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 the third variant of the method, i.e. when step a) is carried out by traction, the method further comprises a subsequent step a2) of positioning a calibration sheath. Said calibration sheath comprises a layer comprising a set of layers A and C or a layer C. Said calibration sheath may comprise the same materials as the layer(s) A of the tubular sheath. When the calibration sheath comprises a layer A and C, the sealed layer C is, before installation, on the outer part of the calibration sheath. When the liner is installed according to this method, the sealed layer C of the tubular sheath is against the pipe, said sealed layer C being on the outer part in contact with the pipe. The calibration sheath is positioned by reversion in the tubular sheath and therefore is found after positioning in the internal part of the jacket, forming an additional thermally insulating layer, the sealed layer C of the calibration sheath being, after installation by reversion, positioned to be in contact with the fluid (at high temperature).

[0037] Another advantage of the present invention is the increase in the insulating power of the jacket, whether it is positioned according to the first, second or third variant of the method. The increase in the insulating power of the jacket makes it possible to compensate for the loss of flow rate that would be due to the reduction in the internal diameter of the renovated pipe and normally makes it possible to avoid replacing the components of the installation such as for example replacing the pump system for distributing the fluid (at high temperature). In addition, when the jacket is installed according to the second variant or according to the third variant, or the fourth variant, the waterproof layer C is in contact with the internal wall of the pipe. The positioning of a waterproof layer against the wall makes it possible to protect the felt layers from possible infiltration of water that could come from outside the pipe in the event of corrosion or damage due to external factors.

[0038] Advantageously, the liner is composed of several layers which are superimposed on each other, facilitating its positioning in the pipe. The superposition of the layers allows greater freedom of movement and flexibility of the superimposed layers and therefore of the liner during positioning, by reversion for example, in the pipe. Indeed, the superimposed layers will be able to slide on each other during turning or traction. Thus surprisingly, for equal thickness, a liner composed of several layers will be installed more easily than a liner composed of a single layer. The superposition of the layers therefore makes it possible to install liners of greater thickness than for liners with a single layer while maintaining the properties of pressure resistance and thermal insulation.

[0039] Advantageously, since the internal temperature and humidity have an impact on the aging of the pipe, the renovation method according to the invention makes it possible to protect the pipe from additional premature aging.

[0040] The curing of the resin after positioning can be done by any known means, in particular by heat, by electromagnetic radiation, by crosslinking at room temperature, etc.

Advantageously, the resin is hardened using heat, the heat source being chosen from water vapor, hot water and/or infrared (IR) radiation. In another embodiment, the hardening can be carried out by UV irradiation, microwave, ultrasound, etc. Advantageously, a “post-hardening” can take place when the network is reopened due to the circulation of a fluid at a temperature higher than the crosslinking temperature of the resin, regardless of the crosslinking method chosen previously.

[0041] Preferably, the curable resin comprises or consists of a polymer chosen from epoxy, polyester, vinylester, silicone, polyimide, polyamide, silicate, polybenzimidazole, polymethacrylate, furan, PEEK, TPU resins, in particular chosen from epoxy and vinylester resins. According to the invention, the curable resin is a resin which can harden under the effect of heat, at room temperature or by electromagnetic radiation (UV, IR, microwave, ultrasound, etc.).

Generally, the tubular sheath and/or the calibration sheath can be impregnated with said curable resin on site or in the factory. The curable resin can harden at room temperature. During factory impregnation, the tubular sheath and/or the calibration sheath whose layers A and/or B are impregnated can be stored for a long time, if the temperature and light conditions are respected.

[0042] Preferably, the jacket has a thickness of between 1.5 mm and 30 mm before installation, in particular between 1.75 mm and 25 mm, advantageously between 2.0 mm and 20 mm before hardening of the resin. Preferably, the renovated pipe has a reduction in its internal diameter, after installation, that is to say after swelling and hardening of the resin, of 1 to 8% of the initial internal diameter, preferably a reduction of 3% of the initial internal diameter.

[0043] The thickness of the jacket can be chosen according to the operating parameters of the pipe such as internal pressure and temperature, as well as according to the state of degradation of the pipe. The thickness must most often meet the standardized dimensional ratio constant (SDR, Standard

Dimension Ratio) which is defined by the ratio between the outer diameter (D) of the jacket and the minimum thickness (e), and is therefore unitless:

SDR = D/e.

[0044] In the context of the invention, the thickness of the liner will preferably be chosen so as to meet the so-called SDR100 requirements, that is to say that the SDR value must be at most equal to 100. In other words, for a given pipe diameter, the minimum thickness of the liner, after installation, must be chosen to have an SDR equal to 100 (SDR100).

The thickness of the jacket, after installation, may therefore have a value lower than SDR100, the reduction in the internal diameter of the renovated pipe being 1 to

20%, preferably 1 to 8% of the initial diameter, more preferably 3% of the initial diameter of the pipe.

[0045] The thickness of the liner may also be determined from the ASTM-F1216-22 standard published in March 2022, concerning the procedures for renovation of pipes by inversion.

[0046] Generally, the closer the SDR value is to 100, the better the internal pressure resistance of the liner.

[0047] A person skilled in the art will be able to choose the number of layers, of strata for each layer, as well as the nature of the woven or non-woven fibers making up the strata, depending on the thermal insulation properties, mechanical resistance, thickness and installation constraints (by traction or by reversion) in the pipe to be renovated.

[0048] According to a particularly preferred embodiment, the metal pipe is renovated by installing a jacket inside the pipe, in which said jacket comprises at least one tubular sheath impregnated with a hardenable resin or a tubular sheath and a calibration sheath impregnated with a hardenable resin, according to the first variant of the method and in which the tubular sheath comprises, before installation from the inside to the outside, a stack of layers A-B-A-C. In this embodiment, layer B is between two layers A. It has been observed that in this configuration, the reinforcing layer B makes it possible to improve the mechanical properties of all the layers, i.e. layers A and C, improving the properties of the tubular sheath.

[0049] When installation according to the third variant of the method is not possible, in particular due to constraints related to the size and/or shape of the pipe to be renovated, the person skilled in the art may choose to install the jacket according to the second variant of the method, installing before step a) a waterproof layer C according to step a1) which may be carried out by reversion or by traction. The tubular sheath is then installed according to step a), the waterproof layer C is therefore between the pipe and the tubular sheath, thus acting as a protective and waterproof layer. Advantageously, once installed according to step a1) followed by step a), the tubular sheath will not stick directly to the wall, and will therefore be more resistant to variations in size by expansion/contraction of the metal pipe which could be due to temperature variations during commissioning and during use of the metal pipe. The liner thus positioned will not stick to the metal pipe after swelling and will therefore be less likely to break or become brittle depending on external conditions.

[0050] Another advantage of the method is that it allows the installation variant to be selected according to the configuration of the pipeline to be renovated and therefore allows all buried and overhead pipelines to be renovated over lengths of approximately 150 to approximately 200 m or more in one operation. In addition, the method allows pipelines that have changes in direction to be renovated, without it being necessary to dismantle the elbows.

[0051] In the context of the present invention, layers A, B and C are as defined above.

[0052] According to a second aspect of the invention, the present invention relates to a renovation kit for a metal pipe, comprising at least one tubular sheath and a hardenable resin, in which the wall of said tubular sheath comprises from the inside to the outside a stack of layers B-C, A-B-C, B-

A-C, B-A-B-C, A-B-A-B-C or A-B-A-C.

[0053] According to another preferred embodiment, the renovation kit for metal pipes comprises a waterproof layer C, a tubular sheath and a hardenable resin in which the wall of said tubular sheath comprises from the inside to the outside a stack of layers B-C, A-B-C, B-A-C, B-A-B-C,

A-B-A-B-C or A-B-A-C. According to another preferred embodiment, the renovation kit further comprises a calibration sheath, in which the wall of said calibration sheath comprises, before installation, a layer C or from the inside to the outside a stack of layers A-C.

[0054] According to another embodiment, the renovation kit comprises a tubular sheath and a curable resin in which the wall of said tubular sheath comprises, before installation from the inside to the outside, a stack of layers C-B-C, C-A-B-C, C-B-A-C, C-A-B-A-B-C or C-A-B-A-C. According to a third aspect of the invention, the present invention relates to a renovated metal pipe, which comprises a cured jacket comprising from the outside to the inside a stack of layers B-C, A-B-C, B-A-C, B-A-B-C, A-B-A-B-C,

A-B-A-C, C-B-C, C-A-B-C, C-B-A-C, C-B-A-B-C, C-B-A-B-A-C, C-A-B-A-B-C, C-A-

B-A-C, C-A-A-B-C, C-B-A-A-C, C-B-A-B-A-A-C, or C-A-B-A-A-C.

[0055] In the context of the present invention, layers A, B and C are as defined above, after their hardening.

[0056] According to another aspect of the invention, the invention relates to the use of a renovation kit for the renovation by internal coating of a water pipe, in particular a district heating pipe.

[0057] In the context of the invention, all the numerical values cited, whether explicitly preceded by the term “approximately” or not, represent a range of values from “10% to +10%, preferably from -5% to +5%, in particular from -2.5% to +2.5% of said numerical value.

Brief description of the drawings

[0058] Other features and characteristics of the invention will emerge from the detailed description of some advantageous embodiments presented below, by way of illustration, with reference to the attached drawings. These show:

Fig. 1: is a cross-section of the tubular sheath before installation;

Fig. 2: is a cross-section of the liner after installation when step a) is performed by traction followed by step a2);

Description of a favorite execution

[0059] Fig. 1 shows a cross-section of a non-reversed tubular sheath 10, designed for the renovation of metal pipes, and which comprises from the inside to the outside, a layer A 11, a layer B 12, a layer A 13.b and a layer C 13.a. The layer C 13.a, which after installation by reversion will be located in the internal part, is composed of polymers and is mechanically or not bonded to a layer A composed of one or more layers of woven or non-woven fibers 13.b. The layer A 13.b is generally composed of (layers of) flexible woven or non-woven materials such as synthetic fiber felts or a mixture of synthetic fibers and/or mineral fibers and/or natural fibers. The impermeable layer C 13.a generally comprises or consists of polymers selected from polyurethanes, polyethylenes, ethylene-propylene-diene polymers (EPDM), silicones, polypropylenes, polyimides, polyetheretherketones (PEEK), polybenzimidazoles or mixtures thereof, and is designed to isolate the structural sheath from the pipe and the fluid. The tubular sheath is designed to have the layer 13.a on its outer surface, in order to allow easier handling of the tubular sheath. In addition, the tubular sheath is also designed to be impregnated with a curable resin. All of the impregnable layers of the tubular sheath, i.e. all of the layers of the tubular sheath with the exception of the layer

C waterproof, are therefore impregnated with said resin, the waterproof C layer 13.a making it possible to isolate the impregnated resin before installation in the pipe, thus preventing it from flowing outside the tubular sheath during handling.

[0060] Layer B 12 of the tubular sheath comprises or is made of reinforcing fibers and is placed between layers 11 and 13, the assembly forming the tubular sheath. The layers of reinforcing fibers may comprise or be made of glass, carbon or aramid fibers or mixtures thereof. The intermediate layer makes it possible to improve the resistance to internal pressure in order to prevent the tubular sheath from deteriorating. The thickness and the number of layers of reinforcing fibers are determined according to the characteristics of the pipe to be renovated, namely the size of the pipe, the temperature and pressure of the fluid, etc.

[0061] Layer A 11, which after installation by reversion will be on the outside, generally comprises or consists of the same material (or similar) as layer 13.b, or generally comprises or consists of one or more layers of synthetic woven or non-woven fibers and/or mineral fibers and/or natural fibers or a mixture thereof.

[0062] Fig. 2 shows a cross-section of a jacket 20 installed according to the third variant of the method, by translation during step a) and which further comprises a calibration sheath 14 installed by reversion during step a2).

The calibration sheath comprises a set of layers A-C, respectively 14.b and 14a. For the sake of clarity, the curable resin and the pipe are not reproduced in the figure. The tubular sheath being positioned by translation, comprises from the outside to the inside, a sealed layer C 13.a, a layer A 13.b, a reinforcing layer B 12 and a layer A 11. The tubular sheath being positioned by translation, the sealed layer C 13.a is on the external part of the jacket, that is to say in contact with the pipe. An advantage of this embodiment is the possibility for the jacket not to adhere to the pipe, allowing said jacket to have better resistance to movements of the pipe. Inside the tubular sheath is then installed during step a2) by reversion, the calibration sheath 14. The calibration sheath being installed by reversion, the sealed layer C 14.a is found on the internal face of the jacket, that is to say in contact with the fluid (at high temperature).

[0063] Example A:

[0064] Example A describes liners for the renovation of a pipeline having an internal diameter before renovation of 150 mm. The parameters of the pipeline are summarized in Table 1.

[0065] Table 2 describes the final minimum thicknesses, after installation, of liners 1, 2 and 3, to renovate the pipe of Table 1, as well as the corresponding initial thicknesses (before installation). The thickness is defined by the constant SDR100 (SDR = 150/1.5 = 100) for liner 1, by the ASTM-

F1216-22 for shirts 2 and 3.

[0066] Table 3 describes the composition and thicknesses of each layer (before installation) of the liners 1, 2 and 3. The liner 1 is installed according to the second variant of the method, i.e. according to step a1) then a) by reversion, the liner 2 is installed according to the first variant of the method, i.e. according to step a) by reversion, the liner 3 is installed according to the third variant of the method, i.e. according to step a) by traction followed by step a2).

The final thickness after installation corresponds to the value of the thickness of the installed, inflated and resin-cured liner. The initial thickness corresponds to the thickness of the liner before installation, the liner impregnated with curable resin.

Table 1: parameters of the pipe to be renovated pes

Table 2:

OD

Final thickness, after installation [mm] 1.6-4.2 5.9-7.2 9.1-11.7 mL ET 1

Table 3: bi A ea A not ES

Who

[0067] Example B:

[0068] Example B describes liners for the renovation of a pipeline having an internal diameter before renovation of 600 mm. The parameters of the pipeline are summarized in Table 4.

[0069] Table 5 describes the final minimum thicknesses, after installation, of liners 4, 5 and 6, to renovate the pipe of Table 1, as well as the corresponding initial thicknesses (before installation). The thickness is defined by the constant SDR100 (SDR = 600/6 = 100) for liner 4, by the ASTM-

F1216-22 for shirts 5 and 6.

[0070] Table 6 describes the composition and thicknesses of each layer (before installation) of the liners 4, 5 and 6. The liner 4 is installed according to the second variant of the method, i.e. following step a1) then a) by reversion, the liner 5 is installed according to the first variant of the method, i.e. following step a) by reversion, the liner 6 is installed according to the third variant of the method, i.e. following step a) by traction followed by step a2). The final thickness after installation corresponds to the value of the thickness of the installed, inflated liner whose resin has been hardened. The initial thickness corresponds to the thickness of the liner before installation, the liner impregnated with hardenable resin.

[0071] Table 4:

Pipe diameter [mm] <0

Internal pressure [bar]

Depression [bar] 08

Pipe depth [m]

Hydrostatic level [m]

[0072] Table 5:

DT

Final thickness, after installation [mm] 6.4 10.1-11.4 17.8-20.4 (ASTM- (ASTM- (SDR100) | 1216-22) | F1216-22)

Initial thickness, before installation [mm] 6.7-9.3 13.7-15 21.4-24

[0073] Table 6: pee TEA IE am [EE am [EE am OO

[0074] Examples A and B describe a method of renovating metal pipes having different diameters. The installation method can be adapted depending on the thickness of the jacket and the configuration of the pipeline.

Legend :

Tubular sheath 11 Layer A 12 Layer B 13a Waterproof C layer 13.0 Layer A 14 Calibration sheath 14a Waterproof C layer 14b Layer A

Claims (1)

Claims 1. A method of renovating a metal pipe, by installing a jacket inside the pipe, in which said jacket comprises at least one tubular sheath impregnated with a curable resin or a tubular sheath and a calibration sheath impregnated with a curable resin, in which - the method comprises in a first variant the steps: a) positioning in the pipe said tubular sheath impregnated with a curable resin by reversion; b) curing the curable resin; the wall of the tubular sheath comprising, before installation from the inside to the outside, a stack of layers B-C, A-B-C, B-A-C, B-A-B-C, A-B-A-B-C or A-B-A-C; or - the method comprises in a second variant the steps: a1) positioning in the pipe a layer C by reversion or by translation; a) positioning in the pipe, inside layer C, said tubular sheath impregnated with a resin curable by reversion; b) curing the curable resin; the wall of the tubular sheath comprising, before installation from the inside to the outside, a stack of layers B-C, A-B-C, B-A-C, B-A-B-C, A-B-A-B-C or A-B-A-C; or - the method comprises in a third variant the steps: a) positioning in the pipe said tubular sheath impregnated with a resin curable by translation; a2) positioning in the pipe, inside the tubular sheath, said calibration sheath impregnated with resin curable by reversion; b) curing the curable resin; the wall of said tubular sheath comprising, before installation from the inside to the outside, a stack of layers B-C, A-B-C, B-A-C, B-A-B-C, A-B- A-B-C or A-B-A-C and the wall of said calibration sheath comprising, before installation, a layer C or from the inside to the outside a stack of layers A-C; or - the method comprises in a fourth variant the steps: a) positioning in the conduit said tubular sheath impregnated with a resin which can be hardened by reversion or translation; b) hardening the hardenable resin; the wall of the tubular sheath comprising, before installation from the inside to the outside, a stack of layers C-B-C, C-A-B-C, C-B-A-C, C-A-B-A-B-C or C-A-B-A-C; - A representing independently at each occurrence a layer comprising a number k of strata of woven or non-woven fibers comprising synthetic, natural or mineral fibers, or a mixture thereof, k being an integer from 1 to 20; - B representing independently at each occurrence a layer comprising a number n of strata of woven or non-woven synthetic, natural or mineral fibers, or a mixture thereof, comprising at least 30%, preferably at least 70%, more preferably 100% by weight of the radially oriented fibers of the tubular sheath, called reinforcing fibers, wherein the reinforcing fibers are chosen from polyester, polyamide, acrylic, phenolic, aramid fibers, glass, carbon, ceramic, basalt, linen, hemp fibers or mixtures of two or more of these types of fibers, and/or from fibers having a tenacity of 30 to 500 cN/tex, n being an integer from 1 to 20; - C representing independently at each occurrence a fluid-tight layer resistant to temperatures of at least 60°C, comprising or consisting of polymers chosen from polyurethanes, polyethylenes, ethylene-propylene-diene polymers (EPDM), silicones, polypropylenes, polyimides, polyetheretherketones (PEEK), polybenzimidazoles or mixtures thereof. 2. Renovation method according to claim 1, in which the or each layer A comprises independently at each occurrence a number k of layers of woven or non-woven fibers comprising synthetic, natural or mineral fibers or a mixture thereof, chosen from polyester, polyamide, acrylic, phenolic, aramid fibers, glass, carbon, ceramic, basalt, linen, hemp fibers and mixtures of two or more of these types of fibers, k being an integer from 1 to 20. 3. Method for renovating a pipe according to any one of the preceding claims, in which the or each fluid-tight layer C independently at each occurrence is resistant to temperatures ranging from 60 to 200 °C, preferably 150 °C continuously; and/or resistant to temperatures of 180, 190, 200, 300 and/or 400 °C at peak temperature; and/or resistant to pH ranging from 1 to 14. 4. Method for renovating a pipe according to any one of the preceding claims, in which the or each layer A independently at each occurrence comprises from 20 to 80% by weight of reinforcing fibers, preferably from 25 to 50% by weight of reinforcing fibers, more preferably 30% by weight of reinforcing fibers. 5. Method for renovating a pipe according to any one of the preceding claims, in which the or each layer B independently at each occurrence comprises fibers having a tenacity of 30 to 500 cN/tex, preferably of 150 to 250 cN/tex. 6. Method for renovating a pipe according to any one of the preceding claims, in which the composite formed by the reinforcing fibers of the or each layer B with the hardenable resin, independently at each occurrence has a flexural modulus of 2,000 to 000 MPa, preferably of 5,000 to 10,000 MPa, more preferably of 7,500 to 20,000 MPa. 7. Method for renovating a pipe according to any one of the preceding claims, in which the curable resin comprises or consists of a polymer chosen from epoxies, polyesters, vinylesters, silicones, polyimides, polyamides, silicates, polybenzimidazoles, polymethacrylates, furans, PEEK, TPU, preferably chosen from epoxies and vinylesters. 8. A method of renovating a pipe according to any one of the preceding claims, in which the curable resin is cured using heat, the heat source being chosen from water vapour, hot water and/or infrared radiation. 9. A method of renovating a pipe according to any preceding claim, wherein the curable resin is cured at room temperature. 10. A method of renovating a pipe according to any one of claims 1 to 8, in which the curable resin is cured by electromagnetic radiation, such as UV, microwave or ultrasound radiation. 11. A method of renovating a pipe according to any one of the preceding claims, wherein the liner has a thickness of between 1.5 mm and 30 mm before hardening, preferably from 1.75 to 25 mm, more preferably from 2.0 to 20 mm; and/or wherein the reduction in the internal diameter of the renovated pipe is from 1 to 20%, preferably from 1 to 8% of the initial diameter, more preferably from 3% of the initial diameter. 12. Method for renovating a pipe according to any one of the claims, in which the or each layer C independently at each occurrence is mechanically linked, preferably by extrusion, to the adjacent layer. 13. A renovation kit for a metal pipe, comprising at least one tubular sheath and a curable resin, in which the wall of said tubular sheath comprises, before installation from the inside to the outside, a stack of layers B-C, A-B-C, B-A-C, B-A-B-C, A-B-A-B-C or A-B-A-C; - A representing independently at each occurrence a layer comprising a number k of plies of woven or non-woven fibers comprising synthetic, natural or mineral fibers, or a mixture thereof, k being an integer from 1 to 20; - B representing independently at each occurrence a layer comprising a number n of strata of synthetic, natural or mineral woven or non-woven fibers, or a mixture thereof, comprising at least 30%, preferably at least 70%, more preferably 100% by weight of the fibers oriented in the radial direction of the tubular sheath, called reinforcing fibers, in which the reinforcing fibers are chosen from polyester, polyamide, acrylic, phenolic, aramid fibers, glass, carbon, ceramic, basalt, linen, hemp fibers or mixtures of two or more of these types of fibers, and/or from fibers having a tenacity of 30 to 500 cN/tex, n being an integer from 1 to 20; - C representing independently at each occurrence a fluid-tight layer resistant to temperatures of at least 60°C, comprising or consisting of polymers chosen from polyurethanes, polyethylenes, ethylene-propylene-diene polymers (EPDM), silicones, polypropylenes, polyimides, polyetheretherketones (PEEK), polybenzimidazoles or mixtures thereof. 14. A renovation kit according to claim 13, further comprising a calibration sheath in which the wall of said calibration sheath comprises, before installation, a layer C or from the inside to the outside a stack of layers A-C. 15. Renovation kit according to claim 13, in which the wall of said tubular sheath comprises, before installation from the inside to the outside, a stack of layers C-B-C, C-A-B-C, C-B-A-C, C-A-B-A-B-C or C-A-B-A- C. 16. Renovation kit according to any one of claims 13 to 15, in which the or each layer A comprises independently at each occurrence a number k of layers of woven or non-woven fibers comprising synthetic, natural or mineral fibers, or a mixture thereof, chosen from polyester, polyamide, acrylic, phenolic, aramid fibers, glass, carbon, ceramic, basalt, linen, hemp fibers and mixtures of two or more of these types of fibers, k being an integer from 1 to 20. 17. Renovation kit according to any one of claims 13 to 14, in which the or each layer B independently at each occurrence comprises fibers having a tenacity of 30 to 500 cN/tex, preferably of 150 to 250 cN/tex. 18. A renovation kit according to any one of claims 13 to 17, wherein the composite formed by the reinforcing fibers of the or each layer B with the curable resin, independently at each occurrence has a flexural modulus of 2,000 to 50,000 MPa, preferably of 5,000 to 10,000 MPa, more preferably of 7,500 to 20,000 MPa. 19. Renovation kit according to any one of claims 13 to 18, in which the or each fluid-tight layer C independently at each occurrence is resistant to temperatures ranging from 60 to 200°C, preferably 150°C continuously; and/or resistant to temperatures of 180, 190, 200, 300 and/or 400°C at peak temperature; and/or resistant to pH ranging from 1 to 14. 20. A renovation kit according to any one of claims 13 to 19, wherein the or each layer A independently at each occurrence comprises from 20 to 80% by weight of reinforcing fibers, preferably from 25 to 50% by weight of reinforcing fibers, more preferably 30% by weight of reinforcing fibers. 21. A renovation kit according to any one of claims 13 to 20, in which the curable resin comprises or consists of a polymer chosen from epoxies, polyesters, vinylesters, silicones, polyimides, polyamides, silicates, polybenzimidazoles, polymethacrylates, furans, PEEK, TPU, preferably chosen from epoxides and vinylesters. 22. Renovation kit according to any one of claims 13 to 21, in which the tubular sheath, and/or calibration sheath and hardenable resin assembly has a thickness of between 1.5 mm and 30 mm before hardening, preferably from 1.75 to 25 mm, more preferably from 2.0 to 20 mm. 23. Renovation kit according to any one of claims 13 to 22, in which the layer(s) C are mechanically bonded, preferably by extrusion, to the adjacent layer. 24. Renovated metal conduit which comprises a hardened liner in which the wall of said hardened liner comprises from the outside to the inside a stack of layers B-C, A-B-C, B-A-C, B-A-B-C, A-B-A-B-C, A-B-A-C, C- B-C, C-A-B-C, C-B-A-C, C-B-A-B-C, C-B-A-B-A-C, C-A-B-A-B-C, C-A-B-A-C, C-A-A-B-C, C-B-A-A-C, C-B-A-B-A-A-C, or C-A-B-A-AC; - A representing independently at each occurrence a layer comprising a number k of strata of woven or non-woven fibers comprising synthetic, natural or mineral fibers, or a mixture thereof, k being an integer from 1 to 20; - B representing independently at each occurrence a layer comprising a number n of strata of synthetic, natural or mineral woven or non-woven fibers, or a mixture thereof, comprising at least 30%, preferably at least 70%, more preferably 100% by weight of the fibers oriented in the radial direction of the tubular sheath, called reinforcing fibers, in which the reinforcing fibers are chosen from polyester, polyamide, acrylic, phenolic, aramid fibers, glass, carbon, ceramic, basalt, linen, hemp fibers or mixtures of two or more of these types of fibers, and/or from fibers having a tenacity of 30 to 500 cN/tex, n being an integer from 1 to 20; - C representing independently at each occurrence a fluid-tight layer resistant to temperatures of at least 60°C, comprising or consisting of polymers chosen from polyurethanes, polyethylenes, ethylene-propylene-diene polymers (EPDM), silicones, polypropylenes, polyimides, polyetheretherketones (PEEK), polybenzimidazoles or mixtures thereof. 25. Renovated metal pipe according to claim 24, in which the or each layer A independently at each occurrence comprises a number k of plies of woven or non-woven fibers comprising synthetic, or natural, or mineral fibers or a mixture thereof, chosen from polyester, polyamide, acrylic, phenolic, aramid fibers, glass, carbon, ceramic, basalt, linen, hemp fibers and mixtures of two or more of these types of fibers, k being an integer from 1 to 20. 26. Renovated metal conduit according to any one of claims 24 or 25, in which the or each layer B independently at each occurrence comprises fibers having a tenacity of 30 to 500 cN/tex, preferably of 150 to 250 cN/tex. 27. Renovated metal pipe according to any one of claims 24 to 26, in which the composite formed by the reinforcing fibers of the or each layer B with the curable resin, independently at each occurrence has a flexural modulus of 2,000 to 50,000 MPa, preferably of 5,000 to 10,000 MPa, more preferably of 7,500 to 20,000 MPa. 28. Renovated metal pipe according to any one of claims 24 or 27, in which the or each fluid-tight layer C independently at each occurrence is resistant to temperatures ranging from 60 to 200 °C, preferably 150 °C continuously; and/or resistant to temperatures of 180, 190, 200, 300 and/or 400 °C at peak temperature; and/or resistant to pH ranging from 1 to 14. 29. A refurbished metal conduit according to any one of claims 24 to 28, wherein the or each layer A independently at each occurrence comprises from 20 to 80% by weight of reinforcing fibers, preferably from 25 to 50% by weight of reinforcing fibers, more preferably 30% by weight of reinforcing fibers. 30. Renovated metal pipe according to any one of claims 24 to 29, in which the curable resin comprises or consists of a polymer chosen from epoxies, polyesters, vinylesters, silicones, polyimides, polyamides, silicates, polybenzimidazoles, polymethacrylates, furans, PEEK, TPU, preferably chosen from epoxies and vinylesters. 31. Renovated metal pipe according to any one of claims 24 to 30, in which the reduction in the internal diameter of the renovated pipe is from 1 to 20%, preferably from 1 to 8% of the initial diameter, more preferably from 3% of the initial diameter of the pipe. 232. Use of a renovation kit according to any one of claims 13 to 23, for the renovation by internal coating of a metal pipe, in particular a district heating pipe, an effluent treatment pipe in the paper industry and/or the chemical industry, an offshore platform pipe, a refinery pipe, a brewery pipe.