BR112019015872A2 - electromagnetic method and device for detecting defects - Google Patents

Abstract

the present invention relates to a device for detecting defects in multilayer structures composed of layers of ferromagnetic bars or wires having different orientations. the device first comprises magnetic means suitable for generating, in the upper layer, a channeled magnetic field following the orientation of the magnetic wires of the upper layer and as many magnetic means as there are lower layers located above the layer to be inspected, each magnetic medium being assigned to a lower layer and being suitable for generating, in said lower layer, a channeled magnetic field following the orientation of the magnetic wires in said assigned layer. the device comprises electromagnetic field emission / reception means arranged above the upper layer, suitable for emitting an electromagnetic field in the layer to be inspected and to receive, in response, signals representative of the state of the magnetic wires in the layer to be inspected.

Description

METHOD AND ELECTROMAGNETIC DEVICE TO DETECT DEFECTS

FIELD OF THE INVENTION [001] The invention relates to the field of non-destructive testing, and in particular to an electromagnetic method and device for detecting defects.

STATE OF THE TECHNIQUE [002] Numerous structures, such as suspension bridge cables (consisting of metal strands wound successively in various orientations), tires (incorporating metallic layers in various orientations, in particular on the tread and side walls), pipes submarines for transporting fluids (incorporating iron bars or helically wound wires in several layers to prevent the tube from being crushed) are subjected to high tensions, which can. affect them negatively. Within this last example, they come. flexible oil tubes, or elevation tubes, which are used at sea, which must withstand multiple stresses, including internal and external pressures, longitudinal flexion or even torsion. It is then necessary to inspect these structures regularly to detect any changes that may have severe consequences.

[003] Among the known inspection techniques, electromagnetic non-destructive testing (NDT) is a technique widely used to inspect flat or tubular metal structures and detect defects, such as complete failures, partial failures, such as cracks or cuts, or wear due to corrosion.

[004] US patent 9,213,018 B2 from Innospection Group Limited features a device for non-testing

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2/18

destructive substantially metallic com.ponent.es ΐ 1. Cf -1. Cl O S f tubular, used in several extraction industries and production of oil and gas. The device is based on technique known eddy current test of s t u r t a c t > partial (PSET). A magnetizing unit

allow a partially saturated magnetic field to be generated in the component to be inspected, and the variation in impedance of an eddy current probe composed of

a wrap makes it possible to determine the presence of defects when the reluctance or conductivity of the material changes in a reference value. 0 device proposed combines the probe with a Hall effect sensor, so the adjust the intensity of the magnetic field

partially saturated in the metal layer of the component

While measurement using eddy current probe and s in i progress. This solution generates a magnetic field in the component : and, the direction of the field lines is fixed

regardless of the orientation of the metal structure to be ionized in spec [005] However, some tubular components, such as the elevation tubes used to connect the seabed to an oil platform and bring the extracted oil or gas to the surface, can be flexible and therefore have a structure provided with metal shielding wires in several layers and in different orientations.

[006] Figure 1 schematically illustrates an internal structure typical of a flexible oil lift tube (100). It is generally composed, from the inside out, of an internal housing (102) to prevent the tube from being crushed under the effect of external pressure, of a pressure sheath

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3/18 (104), a pressure chamber (106), an anti-wear layer (108), of shielding which, depending on the application, consists of. several shielding sheets or metal sheets (Ir 0, 1 .i.2) separated by an anti-wear layer (114) and composed of metal wires wrapped around each layer in different orientations; of an external sheath (116).

[007] The test of these flexible multilayer tubes, in particular the test of metal layers, and magnetic, of shielding wires exhibiting different orientations, presents several problems including that of inspecting buried metal layers. US patent 9,285,345 B2 to Innospection Group Limited proposes a non-destructive testing method and device allowing flexible lift tubes to be. inspected in situ. The device, which is based on the same implementation of the partial saturation eddy current test (PSET) technique as the patent of the same applicant mentioned above, makes it possible to obtain a PSET measurement of a second metallic layer by varying the intensity of the magnetic field generated in the lift tube using one. set of magnetizing units surrounding the lift tube. Here, the magnetic field is generated in a certain direction (according to the Figures, along the axis of the tube to be inspected) instead of following the orientation of the magnetic wires. This results in an increase in the reluctance of the magnetic circuit and, for the same energy supply, a decrease in the intensity of the magnetic field in the layers to be magnetized. The disadvantages of this approach, therefore, lie in the need to have magnets

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4/18 very powerful to produce the partial saturation required for PSET. In addition, it is difficult to guarantee the magnetization of a specific layer.

[008] Thus, there is a need for an adequate solution that allows measurements to be made to detect defects by means of non-destructive tests on multilayer structures.

[009] The present invention addresses that need.

SUMMARY OF THE INVENTION [0010] An object of the present invention is to provide a device and a method for detecting defects in flat, cylindrical or otherwise structures, presenting overlapping sheets of ferromagnetic bars or wires in various orientations.

[0011] The device of the invention will be advantageously applied to the detection of defects in structures such as flexible lifting tubes consisting of wires or bars wound in at least two directions, structures such as twisted cables (for suspended bridges, for example) example) or structures such as tire casings.

[0012] Advantageously, the device of the invention requires less energy than the known devices to effectively magnetize the upper wire layers.

[0013] Again with advantage, by dosing the level of magnetization for each upper layer separately, the device of the invention makes it possible to control the magnetization of the layer to be analyzed. It is possible to keep the layer to be inspected in a non-magnetized manner, thus allowing the magnetic field to be better guided to detect flaws in it.

Petition 870190073594, of 7/31/2019, p. 10/83 [0014] To obtain the results sought, what is proposed is a device to detect defects in a layer to be inspected of a structure having a stack of layers formed from an upper layer and one or more lower layers, each layer being made up of magnetic wires, the wires of each layer being oriented differently. The device comprises:

first magnetic means suitable for generating, in the upper layer, a channeled magnetic field following the orientation of the magnetic wires of the upper layer;

as many magnetic means as there are lower layers located above the layer to be inspected, each magnetic medium being assigned to a lower layer and being suitable to generate, in said lower layer, one. channeled magnetic field following the orientation of the magnetic wires of said assigned layer; and

- means of emission / reception of electromagnetic fields disposed above the upper layer, the means of emission and reception being adequate to emit an electromagnetic field in the. layer to be inspected and to receive, in response, signals representative of the state of the magnetic wires in the layer to be inspected.

[0015] According to different variants of modalities:

magnetic means are suitable to generate, in the upper layer and in each lower layer located above the layer to be inspected, a magnetic field totally or partially saturating in each of said layers;

each of the magnetic means is suitable for separately magnetizing said assigned lower layer;

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6/18 ~ Magnetic media are magnets;

- the magnetic means comprise one or more windings fed by direct current;

- the magnetic means comprise one or more windings supplied with energy for a limited time;

- the magnetic means are orientable circuits;

- magnetic media are U-shaped magnetic circuits;

- the arms of the U are articulated;

- the means of emission / reception of electromagnetic fields are electromagnetic eddy current sensors having coils that emit / receive in the common function mode or in the separate function mode;

- the coil axis can be oriented in the direction of the magnetic wires in the layer to be inspected;

- the means of emission / reception of electromagnetic fields are means of alternating current field measurements (ACFM) or magnetic flux flow (MFL) operating with. DC or at very low frequencies;

- the means of emission / reception of electromagnetic fields can be oriented in the direction of the magnetic wires in the layer to be inspected;

- the means of sending / receiving electromagnetic fields further comprise one. magnetic circuit suitable to induce, in the lower layer to be inspected, a magnetic field for magnetization according to the orientation of the wires in said layer to be inspected;

the device further comprises suitable means for processing and analyzing signals representative of the state of the magnetic wires in the layer to be inspected;

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7/18 ~ the structure is a tubular tube;

- the structure is a flexible lifting tube.

[0016] The invention also encompasses a non-destructive test system including any of the variants of the device of the invention.

[0017] The invention also covers a method to detect defects in a layer to be inspected of a structure having a stack of layers formed by an upper layer and one or more lower layers, cacia camacia being constituted by magnetic wires, the wires of each layer being oriented differently. The method comprises the steps of:

- generate, in the upper layer, a channeled magnetic field following the orientation of the magnetic wires of the upper layer by means of first magnetic means and by means of as many magnetic means as they are. the lower layers located above the layer to be inspected, where each magnetic medium is assigned to a lower layer, one. channeled magnetic field following the orientation of the magnetic wires of said assigned layer;

emit an electromagnetic field in the layer to be inspected by means arranged above the upper layer; and

- receiving, in response, signals representative of the state of the magnetic wires in the layer to be inspected.

[0018] Various aspects and advantages of the invention will appear in support of the description of a 'preferred, but not limiting, mode of implementation of the invention, with reference to the Figures below:

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[0019] A Figure 1 2.1 u s schematically s the estr uture internal · a tube petr ó 1 and f 1 e x í v e 1; [0020] A Figure P illustrates schema ..cently an mo d a 11. d a α e variant of i device nvention for. inspect a structure ture two-layer;

[0021] Figures 3a and 3b show, in section along XZ and YZ, the device according to Figure 2;

[0022] Figure 4 schematically illustrates another variant embodiment of the device of the invention for inspecting a two-layer structure;

[0023] Figures 5a and 5b illustrate, in section along XZ and YZ, the device according to Figure 4;

[0024] Figure 6 schematically illustrates a variant embodiment of the device of the invention for inspecting a three-layer structure;

[0025] Figure 7 illustrates the device according to. Figure 6 in a top view;

[0026] Figures 8a and 8b show an embodiment of a non-destructive test system including the device of the invention according to Figure 2 in. perspective from the side and from above;

[0027] Figure 9 illustrates the articulations of the arms of a magnetic U;

[0028] Figures 10a and 10b show an embodiment of a non-destructive test system including the device of the invention according to Figure 6 in perspective from the side and from above.

DETAILED DESCRIPTION OF THE INVENTION [0029] In general, to detect a defect in a given layer (or sheet), the principle is based on

Petition 870190073594, of 7/31/2019, p. 14/83 locally saturate each of the layers located above the layer to be inspected. Using a magnetic circuit assigned to each layer above the layer to be inspected, a permanent magnetic field in the determined direction of each layer is generated. The magnetic circuit assigned to each layer is oriented in the direction of the shielding wires of the layer. The saturation of each layer is controlled independently and can be complete or partial for each layer.

[0030] According to the variant modalities, the permanent magnetic field can be generated in each layer by means of magnets or by means of one or more windings fed by DC current or windings that are supplied with energy for a limited time around the measurement time in order to decrease heating or to prevent the sensor from being attracted to the magnetic parts. Alternatively, the power supply can vary over a cycle, at various positions on the device for making measurements. A person skilled in the art can derive variants, such as applying pulsed or alternating cycles by position, in order to. demagnetize the materials by suppressing or attenuating the residual magnetic fields, then providing a pulse of DC voltage in order to make the measurement.

[0031] To perform the measurement by means of non-destructive tests, an electromagnetic sensor is positioned on the surface of the structure to be inspected, above the zone that is magnetized through the various layers, and is oriented in the direction of the wires of the layer to be inspected and moved along a wire or transferred over the surface of the

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10/18 structure, in order to produce a map of the tube to be p ried out.

[0032] According to. a variant modality, the electromagnetic sensor is a eddy current sensor (CE), which is well known. An EC sensor generally comprises at least one thermal circuit supplied with AC to produce a local electromagnetic shell and at least one receiver that is sensitive to this electromagnetic field. The electromagnetic receiver generally consists of a receiving coil (possibly several connected together, for example, in differential mode), through the terminals from which an electromotive force of the radius is generated at the frequency that the alternating supply current is induced. Thus, the EC sensor of the device of the invention may have coils that emit / receive, in the common function mode or in the separate function mode. They can allow absolute or differential measurement. As the sensor is moved over the surface of a structure to be inspected, the emitter circuit is provided with a sinusoidal signal. An electromagnetic field of the same frequency is then emitted into the air and the structure to be inspected. This results, through the terminals of the receiving coil, in an induced electromotive force that arises both from the coupling between the emitting circuit and the receiving coil and from the magnetic field radiated by the currents induced in the structure (eddy currents). The frequency range can be from a few tens of kilohertz to a few megahertz, typically from 10 kilohertz to 1 megahertz.

[0033] In the event that a non-uniformity is present in the inspected material (typically a crack or a

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11/18 local variation in the properties of the material), the flow of the induced currents is modified. The magnetic field receiver measures the magnetic field resulting from this change in the path of the induced currents.

[0034] According to another variant, the electromagnetic sensor is an alternating current field measurement sensor, or ACFM, operating over a wide range of frequencies, from a few kilohertz to several hundred kilohertz, typically from 1 kilohertz to 300 kilohertz.

[0035] In another variant, the sensor is a magnetic flow flow sensor, or MFL, operating conventionally with DC, or operating in very low fractions between a few hertz and a few tens of hertz, the receiver being a magnetoresistive sensor or a sensor Hall effect. In these customers, the effect of the induced currents is insignificant and only the magnetic properties of the wires are involved.

[0036] The sensor emitter can be formed by means of circular or rectangular windings or by means of a magnetic circuit typically U-shaped (with an air gap), conventionally manufactured from ferrite or laminated iron, potentially laminated , around which windings are wound. The axis of this U is oriented in the direction of the wires of the. buried layer where defect detection is performed.

[0037] The sensor receiver can include windings or field sensors, such as Hall effect sensors or magneto-resistive (MR) sensors. This last family of sensors groups, in particular, anisotropic magnetoresistance (AMR.), Giant magnetoresistance (GMR),

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12/18 tunnel magnetoresistance (TMR) and magnetoimpedance. giant (GMI).

[0038] Optionally, the electromagnetic sensor can also include a magnetic circuit to induce a static magnetic field (in particular along the wire axis) in the layer to be inspected and allow this layer to be inspected to be partially or completely saturated, for example introduce a direct current into the windings.

[0039] Although not illustrated, the device of the invention is coupled (by wire or otherwise) to an electronic circuit comprising a unit suitable for processing and analyzing the measurement signals by the electromagnetic sensor, in order to determine the presence or not of defects in an inspected layer.

[0040] For the sake of clarity of the description and not to limit it, the device of the invention as described in the Figures is for inspecting a structure that has two or three layers of armor. In addition, although the magnetic circuits that generate magnetic fields along the wire axis of the shield layers are illustrated as a circuit with. an. air gap, typically taking a U-shaped geometry, a person skilled in the art is able to derive operational variants of this, geometry. Thus, the U can be with or without shoes (as shown in Figure 9 at the end of the arm). The purpose of these portions is to minimize the air gap (for example, they can be molded to the outside diameter of the pipe to be inspected) or else they can be more complex in shape (beveled feet in particular) in order to increase the flow of the field magnetic

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13/18 through the lios.

[0041] Figures 2 to 5 schematically illustrate variant modalities of the device of the invention for inspecting a two-layer structure. In a simplified way, the structure is composed of a first layer or top shield sheet (201, 301, 401, 501) and a second layer or bottom shield sheet (202, 302, 402, 502), below, which is, for example, the layer to be inspected. The other layers that possibly form the structure, such as those illustrated in Figure 1, are not shown. Again, for the sake of simplicity and clarity, the wire mesh of each shield layer is shown with the wires of each layer being oriented at 90 ° each. relation to others.

[0042] The device of the invention comprises a first magnetic circuit (204, 304, 404, 504), shown in the form of a U, whose axis runs parallel to the wires of the top sheet, allowing them to be magnetized through the application of a direct current. Preferably, the applied current allows the layer to be completely magnetized; however, the magnetization can be partial. The device also comprises an electromagnetic sensor (206, 306, 406, 506) arranged on the surface of the structure. The sensor in the example is shown with two windings operating in a separate emitter / receiver (E / R) mode, whose axis is oriented along the wires of the layer to be inspected. Figures 3a and 3b show, in section along XZ and YZ, the device shown in Figure 2. For the sake of simplicity, a two-layer structure is illustrated; however, a person skilled in the art can apply the

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14/18 example configuration to inspect the second layer in a structure having three or more layers.

[0043] To perform the measurements, the device is preferably moved along the wire axis of the layer to be inspected (as illustrated by arrow D). However, the device can be moved along any axis.

[0 04 4] Figure 4 schematically illustrates another modal i da d < and variant of the device of the invention for

inspect a two-layer structure, and in which one

circuit Additional magnetic (408, 508) is added so the induce a magnetic field in the layer to be

inspected. The additional magnetic circuit is shown in the

form of a U, whose axis runs parallel to the wires of the in layer ferior. Figures 5a and 5b illustrate, in section at the long of XZ and YZ, the device shown in Figure 4. By s imp 1 i c i d the example is based on a structure of two layers; however, one person, expert in the. technique can apply to example configuration to the second inspection C 3 ITi ci Cl 3 d Θ an. structure having three or more layers. [0045] Figures 6 and 7 illustrate schematically

variant modalities of the device of the invention to inject the last layer of a structure of three

Cl 3 m 3. Cl 3 S · In a simplified way, the structure and composed by a first layer or shielding sheet

upper (601, 701), a second layer or upper shield sheet (602, 702) and a third lower layer or shield sheet (603, 703), lower, which must be inspected. The other layers that possibly form the structure, such as those illustrated in Figure 1, are not

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15/18 .shown. Again, for the sake of simplicity and clarity, the yarn mesh of the first and second upper layers is shown with the yarns oriented at 90 ° to each other, and the yarn mesh of the lower third layer is shown with the yarns oriented differently in relation to the two upper layers. Figure 7 shows a view from above of the device shown in Figure 6 and the mesh of the three layers.

[0046] The device of the invention comprises, in this implementation, a first magnetic circuit (604, 704), shown in the shape of a U ”, whose axis runs parallel to the wires of the first upper layer (601, 701), and a second circuit magnetic (610, 710), shown in the shape of a U, whose axis runs parallel to the wires of the second upper layer (602, 702). Each magnetic circuit allows the wires of the corresponding layer to be magnetized by applying a direct current. Preferably, the current applied to the first magnetic circuit allows the first layer to be completely magnetized; however, the magnetization can be partial. Regardless, the current applied to the second magnetic circuit preferably allows the second layer to be completely magnetized; however, the magnetization can be partial. The device further comprises an electromagnetic sensor (606, 706) disposed on the surface of the structure. The sensor is shown with two windings operating in separate I / R (emitter / receiver) mode, whose axis is oriented along the wires of the lower layer to be inspected (603, 703). To make the measurements, the device is preferably moved along the axis of the

Petition 870190073594, of 7/31/2019, p. 21/83 wires of the third layer to be inspected (as illustrated by the arrow Dj.

[0047] Figures 8a and 8b show an embodiment of a non-destructive test system including the device of the invention according to Figure 2 in perspective from the side (Figure 8a) and from above (Figure 8b). It should be noted that the wires are not shown in these figures for the sake of clarity, the wires of the upper layer being oriented in the same direction as that of the U and the wires of the lower layer being oriented symmetrically with respect to those of the upper layer in relation to the axis the flexible tube. The system comprises a conveyor (802) in which a U-shaped magnetic circuit, composed of two

arms (8 04-1, 804-2) and a winding central (805), is mounted. 0 obj e : tivo d .the magnetic circuit is magnetize the s wires from layer super: or to decrease su The permeability relative. 0 si s t ema understands means to jC a position O hey sensor .etroma gnetic i (806) on the surface d the structure. 0 dimension forgive and the coil position: s emitter θ

sensor receiver are optimized for the structure to be inspected. The sensor is preferably located in the center of the magnetic circuit with a minimal air gap in. relative to the cylinder a. be inspected. In an implementation, the coils are in. a thin, adaptable conveyor, such as a PCB, that is thin enough to be flexible and that matches the curvature of the flexible tube.

[0048] The conveyor comprises fixing means that allow it to be combined with the diameter of any tube to which it is connected, be it rigid or flexible. The pistons allow the conveyor to be kept in

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17/18 contact with the flexible tube, in order to avoid variations in the air gap as it moves. It is also orientable, in such a way that the electromagnetic sensor it supports is oriented following the orientation of the magnetic wires of the layer to be inspected.

[0049] Advantageously, the magnetic circuit is orientable so as to be positioned along the wire axis of the upper shield layer. The arms of the magnetic circuit are articulated as shown in Figure 9. The articulation of the arms allows the orientation of the U to be adjusted according to the wire orientation of the structure to be inspected and the magnetic circuit to be matched for various pipe diameters. Advantageously, the same sensor device can be used to inspect tubes with different structures.

[0050] Figures 10a and 10b show, a variant m.modality of the non-destructive test system of Figure 8 including the device of the invention according to Figure 6 in perspective from the side (Figure 10a) and from above (Figure 10b). In this implementation, the system comprises one. general carrier (1002) similar to that of Figure 8, in. that two magnetic circuits (604 and 610 of Figure 6), the purpose of which is to magnetize each of the two layers of upper shield (601 and 602 of Figure 6), will be mounted. In this modality, the magnetic circuits take the form of a U. Each circuit consists of two arms (10 04--1, 1004-2) and (1008-1, 100 8-2) and a central winding ( 1005, 1007). The system also comprises means for positioning the electromagnetic sensor (1006) on the surface of the structure. Advantageously, each circuit

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18/18 .magnetic is orientable in order to. be positioned along the wire axis of the upper shield layer that is to be saturated, the U arms being articulated so that the magnetic circuit can be positioned as close as possible to the structure to be inspected. This decrease in air space promotes the penetration of the magnetic field in the layer to be saturated and the same sensor can be used for various pipe diameters.

[0051] Thus, the present description illustrates a preferred implementation of the invention, but is non-limiting. An exemplary application for flexible tubes has been chosen to allow a good understanding of the principles of the invention, but it is by no means exhaustive, and should allow one. expert in the art. provide modifications and implementation variants for other applications. In particular, the device can be adapted to inspect multilayer structures, while maintaining the same principles.

Claims (19)

1. Electromagnetic device to detect defects in a layer to be inspected in a structure having a stack of layers formed by an upper layer and one or more lower layers, each layer being made up of magnetic wires, the wires of each layer being oriented in a different, the device FEATURED by the fact that it comprises: first magnetic means suitable for generating, in the upper layer, a channeled magnetic field following the orientation of the magnetic wires of the upper layer; - as many magnetic media as there are lower layers located above the layer to be inspected, each magnetic medium being assigned to a lower layer and being suitable to generate, in said lower layer, a channeled magnetic field following the orientation of the magnetic wires of said assigned layer ; and - means of emission / reception of electromagnetic fields disposed above the upper layer, the means of emission and reception being adequate to emit an electromagnetic field in the. layer to be inspected and to receive, in response, signals representative of the state of the magnetic wires in the layer to be inspected. 2. Device, according to. claim 1, CHARACTERIZED by the fact that the magnetic means are suitable to generate, in the upper layer and in each lower layer located above the layer to be inspected, a magnetic field totally or partially saturating in each of said layers. 3. Device according to claim 1 or 2, Petition 870190073594, of 7/31/2019, p. 25/83 z / CHARACTERIZED by the fact that each of the magnetic media is suitable for, separately magnetizing a. said bottom layer assigned. 4. Device according to any one of claims 1 to 3, CHARACTERIZED by the fact that the magnetic media are magnets. 5. Device according to any one of claims 1 to 3, CHARACTERIZED by the fact that the magnetic means comprise one or more of the direct current fed. Device according to claim CHARACTERIZED fact that the magnetic means comprise one or more windings fed with energy for one. limited time. 7. Device according to any one of claims 1 to 6, CARAC TE RI ZADO by the fact that the magnetic means are orientable circuits. 8. Device according to any one of claims 1 to 7, CARAC TE RI ZADO by the fact that the magnetic media are U-shaped magnetic circuits. 9. Device, according to. claim 8, CHARACTERIZED by the fact that the arms of the U are articulated. 10. Device according to any one of claims 1 to 9, CHARACTERIZED by the fact that the means of emission / reception of electromagnetic fields are eddy current electromagnetic sensors having coils that emit / receive in the common function mode or in the mode separate function. 11. Device according to claim 10, Petition 870190073594, of 7/31/2019, p. 26/83 CHARACTERIZED by the fact that the coil axis can be oriented in the. direction of the magnetic wires in the layer to be i n s p e c i o n a d. 12. Device according to any one of claims 1 to 9, CHARACTERIZED by the fact that the means of emission / reception of electromagnetic fields are means of measurement of alternating current field (ACFM) or means of flow of magnetic flux (MFL) ), operating with DC or at very low frequencies. 13. Device, according to claim 12, CHARACTERIZED by the fact that the means of emission / reception of electromagnetic fields can be oriented in the direction of the magnetic wires of the layer to be inspected. 14. Device according to any one of claims 1 to 13, CARAC TE RI ZADO by the fact that the means of emission / reception of electromagnetic fields further comprise one. magnetic circuit suitable to induce, in the lower layer to be inspected, a. magnetic field to magnetize according to. the orientation of the wires in said layer to be inspected. Device according to any one of claims 1 to 14, CHARACTERIZED by the fact that it further comprises suitable means for processing and analyzing the signals representative of the state of the magnetic wires in the layer to be inspected. 16. Use of the device as claimed in any of claims 1 to 15 CHARACTERIZED by the fact that it is to inspect a tubular tube. 17. Use of the device as claimed in any of claims 1 to 15 CARAC TE RI ΖΑΡΑ due to the fact that Petition 870190073594, of 7/31/2019, p. 27/83 which is for inspecting a flexible lift tube. 18. Non-destructive testing system CHARACTERIZED by the fact that it comprises a device as claimed in any one of claims 1 to 15. 19. Method for detecting defects in a layer to be inspected in a structure having a stack of layers formed from an upper layer and one or more lower layers, each layer being made up of magnetic wires, the wires of each layer being oriented differently , the CARAC TE RI ZADO method because it comprises the steps of: generate, in the upper layer, a channeled magnetic field following the orientation of the magnetic wires of the upper layer by means of first magnetic means and by means of as many magnetic means as there are lower layers located above the. layer to be inspected, where each magnetic medium is assigned to a lower layer, a channeled magnetic field following the. orientation of the magnetic wires of said assigned layer; emit an electromagnetic field in the layer to be inspected by means arranged above the layer s up θ Γ. -1- Ο -Γ- J Θ - receiving, in response, signals representative of the state of the magnetic wires in the layer to be inspected. 20. Method according to claim 19, CHARACTERIZED by the fact that it is implemented by a device according to any one of claims 1 to 17.