HK1220945B - Process for producing a multilayer pipe having a metallurgical bond by drawing, and multilayer pipe produced by this process - Google Patents

Description

Method for producing a multilayer tube having a metallurgical bond by drawing and a multilayer tube produced by the method

Technical Field

The present invention relates to a method for producing a multilayer tube having a metallurgical bond from at least one inner tube and one outer tube by means of at least one thermomechanical forming step. The tubes produced by this method generally have a corrosion-resistant layer, which enables them to be used in highly corrosive environments and gives them high mechanical strength.

Background Art

Multilayer pipes, such as those with metallurgical bonds (also known as "clad pipes") and mechanical bonds (also known as "lined pipes"), and their production methods are currently the subject of industrial development. These coated pipes are primarily used in the oil industry, where they can be subject to high mechanical stresses and highly corrosive environments. Internally circulating fluids can promote chemical attack on the pipes, necessitating the use of corrosion-resistant alloys.

According to the definitions provided in standards DNV-OS-F101 and API 5LD, composite pipe includes an outer pipe with a corrosion-resistant inner layer, where the bond between these materials is metallurgical. According to the definitions provided in DNV OS F101 and API 5LD, lined pipe includes an outer pipe with a corrosion-resistant inner layer, where the bond between these materials is mechanical.

The prior art comprises several processes for manufacturing composite pipes, generally comprising: a material preparation step, an optional layer step and a cladding step. Two well-known processes used on an industrial scale for large batch production are cladding by rolling and overlay welding.

In the cladding process by plate rolling, two sheets of different materials are rolled simultaneously to form a single clad sheet. This sheet is then processed, formed and longitudinally welded to form a seamed composite pipe.

During the cladding process with weld overlay, the materials are bonded together by depositing fillet welds across the entire inner tube surface. The material used in the fillet welds is typically a corrosion-resistant alloy. The weld deposition process creates a metallurgical bond between the inner and outer materials of the composite tube.

GB2085330 discloses a method for producing a composite tube. The method includes a first cold drawing step to achieve a good mechanical bond between the inner and outer tubes. The intermediate product then undergoes a heating step in a furnace, where the two tubes are bonded together. Subsequently, the intermediate product undergoes a hot working step to form the final product by pressing or rolling. In this document, the composite tube manufacturing process further includes a step of preparing the surfaces to be contacted during the cold drawing step. This step includes cleaning the surfaces to be contacted by polishing. Alternatively, this step may include shot peening the contact surfaces instead of polishing.

Also according to document GB2085330, where the difference in thermal expansion coefficient between the inner and outer tubes is large, the ends of the joined tubes are welded to prevent air from entering between the materials forming the joined tubes, which could affect the quality of the tubes. Typically, a final step of rolling is also required after cold forming and hot forming.

US Pat. No. 3,598,156 discloses a method for producing bimetallic pipe fittings with a joining metal that creates a metallurgical bond between the inner and outer tubes. In the process described in this document, cold expansion of the inner tube is performed using a tapered mandrel, ensuring a secure bond between the three metal layers. The tubes are then heated by electromagnetic coils, causing the inner tube's higher coefficient of expansion to expand more than the outer tube, exerting significant pressure on the joining intermediate layer. Without melting the inner and outer tubes, this joining layer melts and subsequently solidifies again, forming a metallurgical bond between the inner and outer tubes. This document does not mention a subsequent hot drawing step.

Furthermore, this document discloses chemical treatment and/or polishing of the outer and inner surfaces of the inner and outer tubes prior to cold drawing. However, it does not mention shot peening these surfaces to improve surface roughness and contact force. Since this is a composite tube, i.e., two tubes metallurgically bonded together, there is no need to increase the mechanical strength and surface roughness of the bond between the tubes, which would be important for lined tubes. However, improvements in the composite product can be achieved using this treatment.

Methods of composite concentric tubes presented in the prior art have always included preparation steps, steps of forming or depositing the weld material (which forms the metallurgical bond between the tubes), and polishing steps, which are generally between lamination, pressing, rolling, extrusion or cold drawing steps.

None of the prior art methods discloses producing composite tubes in a single forming step, without a polishing step. Furthermore, none of the prior art methods suggests the possibility of performing all steps on a single production line without moving the tube from one workstation to another between steps or moving the heated tube from inside the furnace to the production line, which burdens the production process, speed, and labor. None of the prior art documents disclose seamless multi-layer tubes with metallurgical bonds.

Summary of the Invention

The object of the present invention is achieved by a method for producing a multilayer tube with metallurgical bonding from a tubular element comprising at least one other tube of metallic material and an inner tube of metallic material arranged inside the outer tube, the inner surface of the outer tube being mechanically bonded to the outer surface of the inner tube, the method comprising the following steps:

On a production line, the tubular element is heated and drawn simultaneously, wherein each portion of the tubular element is subjected to heating by induction and then to hot drawing, and wherein the tubular element is drawn with a mandrel located inside it.

The outer tube comprises a carbon-manganese steel alloy, and the inner tube comprises a corrosion-resistant alloy.

Preferably, each section of the tubular element arranged on the production line is heated at a temperature of at least 900° C. when crossing the electromagnetic coil. Also preferably, in the heating and drawing steps, the tubular element is drawn through the interior of at least one electromagnetic coil, where it is heated to a temperature between 950° C. and 1050° C., and is drawn through drawing dies sequentially arranged in the output of the electromagnetic coil, wherein a mandrel is arranged inside the tubular element and aligned with the drawing die opening.

The drawing step may include reducing the wall thickness of the tubular element by compression of the tubular element between the drawing die and the mandrel.

The method may further include at least one heat treatment step after the drawing step, in which the tubular element is cooled. A cold drawing step may also be performed, with the optional prior lubrication of the inner surface of the inner tube and the outer surface of the outer tube to improve geometric tolerances and surface finish. Furthermore, a further step of bending the tubular element may be performed after the drawing step.

The objects of the present invention are achieved by a metallurgically bonded multilayer tube produced by the method described herein, the multilayer tube comprising at least one outer tube of a metallic material and an inner tube of a metallic material arranged within the outer tube, the inner surface of the outer tube being metallurgically bonded to the outer surface of the inner tube, the outer tube being composed of carbon-manganese steel and the inner tube being composed of a corrosion-resistant alloy.

The inner tube of the metal material may be made of at least one of carbon steel, low alloy steel, high alloy steel, stainless steel, nickel-based alloy, titanium-based alloy, cobalt-based alloy, copper-based alloy, tin-based alloy and zirconium-based alloy. The outer tube and the inner tube are preferably seamless tubes.

The multilayer tube may include at least one intermediate layer of a metallic material disposed between the outer tube and the inner tube. The intermediate layer may have a lower melting point than both the outer and inner tubes. The intermediate layer may include nickel (Ni) or zirconium (Zn). The multilayer tube may include an additional outer layer disposed externally of the outer tube, the outer layer being formed from a second outer tube having an inner diameter greater than the outer diameter of the outer tube and metallurgically bonded to the outer tube. The outer layer is preferably formed from a corrosion-resistant alloy, a wear-resistant alloy, and a fatigue-resistant alloy. In the multilayer tube, a 100% metallurgical bond may be achieved between the outer tube and the inner tube.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further described in more detail based on an example of implementation shown in the accompanying drawings. The drawings show:

1 is a schematic diagram of a first embodiment of a hot drawing step of a method for producing a multilayer tube of the present invention;

FIG2 is a block diagram of the steps according to the present invention;

3 is a schematic diagram of a second embodiment of the hot drawing step of the method for producing a multilayer tube of the present invention;

FIG4 is a photograph of the interface between mechanically bonded tubes produced by the method of the present invention, combined with a graph of the concentrations of iron and nickel elements in the interface between the tubes; and

5 is a photograph of the interface between tubes of an embodiment of a metallurgically bonded drawn multilayer tube produced by the method of the present invention, combined with a graph of the concentrations of iron and nickel elements in the interface between the tubes.

DETAILED DESCRIPTION

As can be seen in Figures 1 to 5, the present invention relates to a method for producing a multilayer tube 1 with metallurgical bonding from a tubular element comprising at least one outer tube 10 of a metallic material and one inner tube of a metallic material 20, such that the tube produced by the method is a multilayer tube comprising at least one outer layer made of the outer tube 10, which is at least partially metallurgically bonded to an inner layer made of the inner tube 20. The tubular element may alternatively initially comprise more than two tubes, forming one tube 1 with multiple layers at least partially metallurgically bonded to one another.

The multilayer pipe produced by this method can be a composite pipe when the bonding between the layers of the multilayer pipe produced using the method of the present invention meets the minimum requirements of standards ASTM A578 and API 5LD, namely, any unclad area on the surface of the pipe may not exceed a diameter of 25 mm within a 225 mm by 225 mm square scanned area centered on the discontinuity. Furthermore, the pipe should not have any unclad area within a distance of 100 mm from the end of the pipe. According to the present invention, a composite pipe can be produced using the method of the present invention with 100% cladding between the outer pipe 10 and the inner pipe 20.

The tubes constituting the tubular element are preferably seamless tubes. In this case, the multilayer tube produced by the method according to the invention is also seamless. In an alternative embodiment of the invention, the outer tube 10 can be a seamless tube and the inner tube 20 can be a welded tube.

The inner tube 20 is preferably made of a corrosion-resistant alloy (CRA) and is initially placed inside the outer tube 10, forming a coating for the latter. The inner tube can also be made of a wear-resistant alloy (WRA) or a fatigue-resistant alloy. Generally, the outer tube 10 is responsible for providing the final mechanical strength of the multi-layer tube. It is also important that the inner surface of the outer tube 10 is mechanically bonded to the outer surface of the inner tube 20 so that no oxygen is trapped between the two tubes. The presence of oxygen at the interface between the tubes can lead to the formation of oxides, which form corrosion and can prevent good cladding between the tubes. A tubular element comprising mechanically bonded tubes may be referred to as a liner.

The mechanical bond between the tubes can be formed by any method known in the art, such as mechanical forming steps such as expansion, extrusion, cold drawing, and rolling. Preferably, prior to the mechanical bond forming step, a shot peening step is performed on the inner surface of the outer tube 10 and the outer surface of the inner tube 20 to be mechanically bonded together. These surfaces are preferably struck with steel shot to increase their roughness and optimize the contact force between the materials, thereby improving the mechanical bond between the tubes. The use of steel shot in the shot peening process is advantageous because, since the shot is made of steel, it does not add impurities to the surface of the tubes.

FIG4 illustrates the mechanical bond between the outer tube 10 and inner tube 20 of a lined pipe 1, an example of a product according to the present invention. The figure includes a micrograph of a cross-section (unetched) of the interface between the tubes, with the outer tube 10 shown on the left in a darker shade of gray and the inner tube 20 on the right in a lighter shade of gray. The interface between the tubes in the section corresponding to the upper smaller box is represented by the concentrations of the materials of the two tubes in the graph below it. The graph is an enlarged version of the interface section, with the ordinate indicating the concentration of each element in mass percent and the abscissa indicating the position in the lined pipe perpendicular to the interface. The graph shows the concentrations of the elements iron (Fe) and nickel (Ni) in the X-direction in the interface region between the tubes in the lined pipe. The solid line represents the concentration of iron, one of the main components of the outer tube 10 according to one embodiment of the present invention. The dashed line represents the concentration of nickel in this interface region, with nickel being the main element of the inner tube 20 according to this embodiment of the present invention. The sudden change in the concentration of iron and nickel occurs in the same position of the graph representing the interface area between the tubes. This indicates that there is no significant diffusion between the materials of the two tubes, so that there is only a mechanical bond between them and no metallurgical bond, i.e., no cladding.

FIG2 shows a flow chart of a preferred embodiment of the method according to the invention. After the mechanical joining of the tubes and before the hot drawing, the method according to the invention preferably includes a step of lubricating the inner surface of the inner tube 20 (which will contact the mandrel 2 during the hot drawing step) and the outer surface of the outer tube 10 (which will contact the drawing die 4 during the hot drawing step). This lubrication can also be performed during the drawing step. The flow of lubricant 11 is shown in FIG1 and FIG3. The lubricant acts to reduce the friction caused by the contact between the drawing die and the mandrel with the tubular element. The lubricant 11 used is preferably based on a mixture of water and graphite or any lubricant used for high-temperature processes, such as hex-α-BN. This lubricant has the advantage of not changing the surface chemical composition of the tube.

In the method according to the present invention, a metallurgical bond is formed between the outer tube 10 and the inner tube 20, at least one hot drawing step 22 is performed, and the steps of heating and drawing the tube are performed simultaneously on the same production line. Thus, each section of the tubular element is subjected to induction heating and subsequently hot drawing on the same production line. Drawing occurs with the aid of a mandrel 2 located within the tubular element.

The hot drawing step is preferably performed 1 to 5 times, at a speed varying from 0.1-5.0 m/min, and at a temperature varying from 800-1300°C.

Since the opening of the drawing die 4 has a smaller diameter than the tubular element to be drawn through it, before drawing, the tubular element is preferably subjected to a step of sharpening (pointing), in which the end of the tube is shaped to reduce its outer diameter so that it can initially be drawn through the opening of the drawing die 4. In a preferred embodiment of the invention, the tip of the tubular element is heated on the production line or in a furnace and then shaped to take on the diameter and size required for its drawing through the drawing die. The sharpening can also be produced by cold forging.

During the heating step for performing hot drawing, the tubular element is stretched while passing inside at least one electromagnetic coil 7 arranged on the line, so that when crossing the coil, each tube segment is heated by induction through the Joule effect, reaching a minimum temperature of 900° C. at the exit of the coil, and preferably ranging from 950° C. to 1050° C., depending on the geometry of the tube, the length to be produced, the materials used, the reduction applied and other aspects.

The hot tubular element is then drawn through a drawing die 4 arranged continuously on the same production line in the output of the electromagnetic coil 7. As the tubular element passes the drawing die 4, the mandrel 2 is arranged inside the tubular element aligned with the opening of the drawing die 4.

During the drawing step, the wall thickness of the tubular element can be reduced by compressing the tubular element between the drawing die 4 and the mandrel 2. The compression parameters of the tubular element and the thickness of the final tube can be adjusted to the desired end product. If necessary, in the method according to the invention, more than one cold drawing or hot drawing step can be performed to achieve the desired tube dimensions.

In a preferred embodiment of the invention, the hot drawing step is performed on a drawing station shown in FIG1 , wherein the end of the tubular element is stretched in the direction of the arrow F shown in FIG1 by a vehicle, causing the tubular element to pass through an electromagnetic coil 7 and a drawing die 4, wherein a mandrel 2 is fixed to a connecting rod 3 arranged inside the tubular element. The mandrel 2 is located within the drawing die opening, so that the tubular element passes between the mandrel 2 and the drawing die 4. The drawing equipment can be cooled by circulating water 12 between its components, as can be seen in FIG1 and FIG3 .

The use of an electromagnetic induction coil to heat the tube is advantageous because it allows one to verify the uniform temperature of the tube during heating and dynamically control other process parameters, such as the stage speed and coil power, for proper correction. Furthermore, using this coil to heat while performing the drawing step provides higher heating rates than those achieved through other heating methods. These high heating rates prevent possible grain growth, which can occur during conventional heating if the material is exposed to high temperatures for extended periods.

Another advantage of induction heating achieved in the present invention is that the electromagnetic induction coil is easy to install on the production line, and the movable coil eliminates the need to handle the hot tube, which has a direct impact on safety and also increases the speed of tube production because it eliminates the need to transport the tube from the furnace to the production line. In addition, induction heating eliminates the need to burn fuel gas used to heat the tube in the furnace.

After hot drawing, the tube may be subjected to at least one bending step when it is desired to produce a bent tube in a specific format.

The method according to the present invention may further include a heat treatment step after the heating and hot drawing steps for the purpose of adjusting material properties. These heat treatment steps depend on the mechanical and metallurgical properties of the multilayer tube 1 that may need to be adjusted. Some materials may lose some of their mechanical, metallurgical, and corrosion properties during the production steps. Therefore, these additional heat treatments may be performed to restore the mechanical, metallurgical, and corrosion properties of the tube, for example, when tubes 10 and 20 are made of X65 steel and Inconel. In a preferred embodiment of the present invention, during the heat treatment step, the multilayer tube undergoes a cooling or quenching and tempering step, which helps adjust the mechanical, metallurgical, and corrosion properties of the tube.

Figure 3 schematically shows an embodiment of the invention in which a tube cooling device 8 is arranged in series at the output of the drawing die 4. The form of cooling is determined according to the final parameters of the multilayer tube to be obtained.

Cooling can be effected, for example, on a table lined with refractory material to maintain the high temperature and allow a long diffusion period, or using industrial fans promoting forced convection cooling to increase the mechanical strength of the outer tube and avoid confinement during processing. Cooling can also be atmospheric air only or any other cooling method used to adjust the material properties.

A cold drawing step can also be performed after hot drawing to improve geometric tolerances and surface finish. If cold drawing is performed, prior lubrication of the inner and outer surfaces of the inner and outer tubes can also be achieved. Otherwise, the remaining graphite from the hot drawing step can be used as a lubricant to reduce friction.

Importantly, unlike prior art methods, no additional subsequent rolling step is required after drawing. Figure 5 contains a microscopic cross-sectional image of the interface at the joint between multilayer tubes of an exemplary product according to the present invention, in a portion of the final multilayer tube 1 that forms a metallurgical bond, wherein the outer tube 10 is shown on the left in a darker shade of gray, while the inner tube 20 is shown on the right in a lighter shade of gray. The interface between the inner and outer tubes is effectively non-existent, characterizing the metallurgical bond at these locations within the tubes. The interface between the tubes in the section corresponding to the upper smaller box is represented by the concentrations of the materials of the two tubes in the graph below it. The graph is an enlarged version of the aforementioned interface section, with the ordinate representing the concentration of each element in mass percent and the abscissa representing the location within the multilayer tube. As in Figure 4, the graph shows the concentrations of the elements iron (Fe) and nickel (Ni) along the X-direction in the interface region between the tubes in the portion that forms the metallurgical bond. According to one embodiment of the present invention, the solid line represents the iron concentration of the outer tube 10, and the dashed line corresponds to the nickel concentration of the inner tube 20. Note that the change in iron and nickel concentrations is smooth, indicating a diffusion zone where the two elements are present and, therefore, the materials of the inner and outer tubes are mixed. This indicates a metallurgical bond, i.e., a cladding, between the tubes. Thicker and more uniform diffusion zones generally result in better cladding.

Alternatively, after the tubes have been cooled, a metallurgical bonding test step may be performed to confirm the presence of cladding. The test may be destructive by cutting sections of the tube, for example, at 90° intervals, to verify that the outer and inner tubes remain attached in all of these sections. The test may also be non-destructive, by inspecting by ultrasonic testing, microstructural analysis, cross-section analysis of the interface, scanning electron microscopy/energy dispersive X-ray detector (SEM/EDX) testing, or glow discharge spectroscopy (GDOES) testing, among other means, to verify that metallurgical cladding has been achieved in at least a portion of the tube produced by the method according to the invention.

Compared to prior art methods, the method according to the present invention offers superior performance, as it does not require any displacement of the tube, or of the inner and outer tubes, within the manufacturing apparatus, other than the drawing equipment itself. Furthermore, given the simplicity of the method and the reduced number of steps, it is possible to produce large quantities of multilayer tubes in a short cycle time, with an estimated production rate exceeding 100 m/h.

The present invention also relates to a multilayer tube having a metallurgical bond produced by the method described herein, comprising at least an outer layer formed from an outer tube 10 and an inner layer formed from an inner tube 20, the outer layer being metallurgically bonded to the inner layer in at least a portion of the interface between the two tubes. Alternatively, the multilayer tube may comprise multiple layers having metallurgical bonds on the exterior and interior of the tube 10 in at least a portion of their surface, which provide mechanical strength to the resulting multilayer tube. These layers are preferably made of seamless tubes that are arranged on the exterior of the outer tube 10 and subjected to the hot drawing process described herein. The inner tube 20 and the outer tube 10 are preferably seamless to prevent the produced multilayer tube from having seams on its surface.

The outer tube 10 , which generally provides mechanical strength, comprises a carbon-manganese steel alloy, and the inner tube 20 comprises a corrosion-resistant alloy, a wear-resistant alloy, or a fatigue-resistant alloy.

According to one embodiment of the present invention, the outer tube 10 may have the following chemical composition:

C≤0.30

Mn≤1.40

P≤0.030

S≤0.030

Cu≤0.5

Cr≤0.5

Ni≤0.5

Mo≤0.15

Nb+V+Ti≤0.15

and the following mechanical properties, before and after the method according to the invention (YS=yield strength and UTS=tensile strength):

360MPa<YS<830MPa

455MPa<UTS<935MPa

Minimum elongation εmin = 15%.

The corrosion environment of the corrosion-resistant alloy used for the inner tube 20 corresponds to the environmental levels I to VII of the international standard NACE MR0175.

As described above, other tubes of corrosion resistant alloy (CRA) or wear resistant alloy (WRA) or fatigue resistant alloy may be applied to the outer tube to form an additional outer layer. The inner tube 20 and/or the tube for the outer cladding may be made of a material including at least one of carbon steel, low alloy steel, high alloy steel, stainless steel, nickel-based alloy, titanium-based alloy, cobalt-based alloy, copper-based alloy, tin-based alloy, zirconium-based alloy, and Inconel.

In an alternative embodiment of the present invention, prior to hot drawing, the tubular element includes at least one intermediate layer of metallic material at the interface between the outer tube 10 and the inner tube 20. This intermediate layer of metallic material may have a melting point lower than the melting points of the metallic materials comprising the outer tube 10 and the inner tube 20, but it is not a primary component that ensures a metallurgical bond between the tubes. Therefore, in this embodiment with a hot drawing process, the tubes may be heated to a temperature significantly lower than the reported range of 950°C to 1050°C. The intermediate layer of metallic material may also be formed from a material that has an affinity for the outer tube 10 and the inner tube 20, thereby avoiding the formation of deleterious phases that could weaken the interface between the materials. The intermediate layer may include nickel (Ni), zirconium (Zn), or other metals or metal alloys.

The multilayer pipe produced by this method is a composite pipe when the bonding between the layers forming the multilayer pipe meets the minimum requirements of standards ASTM A578 and API 5LD as described above. According to the present invention, the composite pipe can achieve up to 100% cladding between the outer pipe 10 and the inner pipe 20.

The dimensions of the multilayer tube produced by the method of the present invention will depend on its application. According to one embodiment of the present invention, the tube may have an outer diameter dext ranging from 50.80 mm < dext < 355.6 mm, and a wall thickness WT ranging from 5.0 mm < WT < 30.0 mm, wherein the minimum wall thickness of a tube of a corrosion-resistant alloy for pipeline applications is WTmin-CRA = 2.50 mm.

When compared to the initially assembled tube prior to the production method according to the invention, the total deformation values of the final tube are as follows:

Outer diameter deformation: 0.1 to 20%

Wall thickness deformation: 0.1 to 40%

Wall cross-sectional area deformation: 0.1 to 40%

The examples described above represent preferred embodiments; however, it should be understood that the scope of the present invention encompasses other possible variations and is limited only by the content of the appended claims, which include all possible equivalents.

Claims (15)

1. A method for producing a multilayer tube (1) with metallurgical bonding from a tubular element, said tubular element comprising at least one outer tube (10) of metallic material and an inner tube (20) of metallic material disposed within said outer tube, wherein at least some portions of the interface between said outer tube and said inner tube, the inner surface of said outer tube (10) is mechanically bonded to the outer surface of said inner tube (20), characterized in that the method comprises the following steps: The tubular element is formed by arranging the outer tube (10) of metal material and the inner tube (20) of metal material inside the outer tube, and the inner tube (20) and the outer tube (10) are subjected to mechanical expansion, thereby creating a mechanical bond between the inner surface of the outer tube and the outer surface of the inner tube along the entire interface of the tubular element. On the production line, the tubular element is simultaneously heated and drawn to change its diameter from a first diameter to a smaller second diameter, wherein each portion of the tubular element is heated by induction and then thermally drawn, and wherein the tubular element is drawn using a mandrel located within the tubular element. In the step of simultaneously heating and drawing the tubular element, a metallurgical bond is directly formed between the inner surface of the outer tube and the outer surface of the inner tube in the diffusion region where the materials of the inner tube and the outer tube are mixed. Following the steps of simultaneously heating and drawing, the method further includes a step of forced convection cooling of the tubular element. 2. The method according to claim 1, wherein the outer tube (10) is made of carbon manganese steel alloy and the inner tube (20) is made of corrosion-resistant alloy. 3. The method according to claim 1 or 2, characterized in that each segment of the tubular element is heated at a temperature of at least 900°C when intersecting with an electromagnetic coil (7) arranged on the production line. 4. The method according to claim 1 or 2, characterized in that, in the heating and drawing steps, the tubular element is drawn through the interior of at least one electromagnetic coil (7), wherein the tubular element is heated to a temperature between 950°C and 1050°C, and the tubular element is drawn through a drawing die continuously arranged at the outlet of the electromagnetic coil (7), wherein the mandrel (2) is disposed inside the tubular element and aligned with the opening of the drawing die (4). 5. The method according to claim 4, wherein the drawing step comprises reducing the wall thickness of the tubular element by compressing the tubular element between the drawing die (4) and the mandrel (2). 6. The method according to claim 1 or 2, characterized in that, after the hot drawing step, the method includes: a subsequent cold drawing step, and a pre-lubrication step of the inner surface of the inner tube (20) and the outer surface of the outer tube (10). 7. The method according to claim 1 or 2, characterized in that, after drawing, the method includes a bending step of the tubular element. 8. The method according to claim 1 or 2, characterized in that, when producing the multilayer tube, 0.1% to 20% of the outer diameter deformation, 0.1% to 40% of the wall thickness deformation and 0.1% to 40% of the wall cross-sectional area deformation are provided together to the installed outer tube and the inner tube. 9. A multilayer tube (1) having a metallurgically bonded structure produced by the method according to any one of claims 1 to 8, characterized in that the multilayer tube comprises at least one outer tube (10) of metallic material and an inner tube (20) of metallic material disposed within the outer tube, wherein at at least some portions of the interface between the outer tube and the inner tube, the inner surface of the outer tube (10) is metallurgically bonded to the outer surface of the inner tube (20), the outer tube (10) being made of carbon manganese steel, and the inner tube (20) being made of a corrosion-resistant alloy. The multilayer tube includes a metallurgical bond between the inner surface of the outer tube and the outer surface of the inner tube in a diffusion region where the materials of the inner tube and the outer tube are mixed. 10. The multilayer tube (1) according to claim 9, characterized in that the inner tube (20) of the metal material is made of at least one material including carbon steel, low alloy steel, high alloy steel, stainless steel, nickel-based alloy, titanium-based alloy, cobalt-based alloy, copper-based alloy, tin-based alloy, zirconium-based alloy and. 11. The multilayer tube (1) according to claim 9 or 10, characterized in that the outer tube (10) and the inner tube (20) are seamless tubes. 12. The multilayer tube (1) according to claim 9 or 10, characterized in that the outer tube (10) is a seamless tube and the inner tube (20) has a weld. 13. The multilayer tube (1) according to claim 9 or 10, characterized in that the multilayer tube further includes an outer layer disposed outside the outer tube, the outer layer being made of a second outer tube having an inner diameter greater than the outer diameter of the outer tube (10), and the outer layer being metallurgically bonded to the outer tube (10). 14. The multilayer tube (1) according to claim 13, wherein the outer layer is composed of one of a corrosion-resistant alloy, a wear-resistant alloy, and a fatigue-resistant alloy. 15. The multilayer tube (1) according to claim 9 or 10, characterized in that 100% metallurgical bonding is achieved between the outer tube (10) and the inner tube (20).