Method for checking the adhesive thickness between two composite sheets of a liquefied gas tank wall and related apparatus

Abstract

The invention relates to a method for checking the adhesive thickness between two composite sheets of a tank wall for liquefied gas and a related apparatus, in particular to a method for checking the adhesive thickness in a checking zone extending between an upper composite sheet (133) and a lower composite sheet (231) located on at least one tank wall (7, 8), the checking method comprising the steps of: - positioning one end (66) of an electromagnetic field transmitter (65) on the upper composite sheet (133) on a current portion (Pi) of the checking zone, the end of the electromagnetic field transmitter being shaped to fit the upper composite sheet of the current portion; - generating a variable magnetic field by the electromagnetic field transmitter to generate an induced current flowing in the current portion (Pi); - receiving a signal (69) having a magnetic phase difference characterizing the distance (60) between the upper composite sheet and the lower composite sheet; - determining the adhesive thickness in the current portion from the magnetic phase difference.

Description

Technical Field

[0001] This invention relates to the field of tanks for liquid gases (e.g., liquefied natural gas (LNG)), particularly for marine or river transport or for onshore storage. More specifically, this invention relates to an apparatus and method for inspecting the thickness of the adhesive between two composite sheets of the wall of a tank intended to contain liquefied gas. Background Technology

[0002] Each tank used for transporting liquefied gases has a capacity of several thousand cubic meters of liquefied gas, or even tens of thousands of cubic meters. Containers for transporting liquefied gases have cargo holds specially arranged to house these tanks, and the cargo holds of the container are typically divided into multiple tanks. Such tanks can also be manufactured externally for use in onshore storage of liquefied natural gas.

[0003] The gas is stored in these tanks in a liquid state for transport or storage; for example, LNG has a temperature of -163°C at atmospheric pressure. Therefore, the tanks must be sealed and insulated.

[0004] Figure 1 A schematic cross-sectional view of the wall of a prior art tank for transporting and / or storing liquefied gases is shown. The tank includes a support structure 50, and this wall typically consists of two consecutive sealing membranes: a primary membrane 10 designed to contact the product contained within the tank, and a secondary membrane 30 positioned between the primary membrane 10 and the support structure 50 (e.g., an internal partition of the container). Each of these membranes is associated with an insulating barrier. Thus, the primary insulation includes the primary membrane 10, which abuts against a primary insulating barrier 20, which in turn is positioned against the secondary membrane 30, which abuts against a secondary insulating barrier 40 fastened to the support structure 50. The primary membrane 10 is typically made of stainless steel and includes corrugations extending from its surface. These corrugations are intended to impart flexibility to the primary membrane to accommodate the thermal contraction of the steel as the tank cools. Preferably, the insulating blocks forming the insulating barriers 20, 40 are made of reinforced polyurethane foam.

[0005] The secondary membrane 30 includes at least one continuous thin composite sheet, such as aluminum, inserted between two sheets of fiberglass cloth, with an adhesive ensuring cohesion between the fiberglass cloth and the aluminum. This thin composite sheet is also referred to as a rigid secondary barrier (RSB). This sheet will be referred to as a rigid sheet. This sheet covers each of the insulation blocks in the insulation barrier 40, such as blocks 31 and 32 of wall 8 and blocks 33 and 34 of wall 7. Although this sheet is not directly visible, it is... Figure 1 Block 32 is shown to illustrate its positioning on the tank wall. Figure 2Block 32 can be seen in the image. It should be noted that the insulating element 41 (e.g., glass wool) is positioned between the two insulating blocks 31 and 32 and between the two insulating blocks 33 and 34 of the second insulating barrier 40, and is also positioned between insulating blocks 31 and 33 and between 32 and 34 to fill the gaps between the insulating blocks 31, 32, 33, and 34. The insulating element 41 forms an insulating seal between the supporting structure 50 and the secondary sealing membrane 30.

[0006] A continuous thin composite sheet 130 is bonded at the joint between two series of insulation blocks to ensure the continuity of the barrier. This thin composite sheet 130 is made of aluminum sheet inserted between two layers of fiberglass cloth and has a degree of flexibility. Sheet 130 is also referred to as a Flexible Secondary Barrier (FSB). This sheet will be referred to as a flexible sheet. Layers of rigid sheet (RSB) and flexible sheet (FSB) stacked on the flat portion of the wall have been described here. (Refer to...) Figure 2 Describe the details of the components in the angular region between the two walls 7 and 8.

[0007] It should be noted that the arrangement of one or more insulating elements and membranes described above by way of illustration is not, in any way, limiting. The invention relates more specifically to the bonding region of two flexible sheets.

[0008] Figure 2 The diagram schematically illustrates the corner region of the can at the intersection of the two can walls 7, 8 during assembly in the prior art. The two walls 7, 8 form an angle A between the two walls, for example, 90° or 135° (here, angle A is 135°).

[0009] The corner region is comprised of two pre-assembled blocks 70, 80 and a thermal insulation element 41 located between the blocks 70, 80 to provide a thermal seal between the two pre-assembled blocks 70, 80. Each pre-assembled block includes two thermal insulation blocks (pre-assembled block 80 includes two thermal insulation blocks 31, 33, and pre-assembled block 70 includes two thermal insulation blocks 32, 34), each thermal insulation block being positioned on wall 7 or 8 to form the aforementioned angle. For each pre-assembled block, a thermal insulation element, such as one made of glass wool, is typically inserted between the two thermal insulation blocks.

[0010] In this corner region, for each pre-assembled block (e.g., block 80), a rigid sheet (RSB) 131 is bonded to each of the insulation blocks 31, 33 of the two tank walls 7, 8. Similarly, for block 70, a second rigid sheet (RSB) 132 is bonded to each of the two insulation blocks 32, 34 of the two tank walls 7, 8.

[0011] For pre-assembled block 80, a flexible sheet (FSB), referred to as lower composite sheet 231, is bonded to the intersection of the two tank walls 7, 8. The flexible sheet covers the joint between the two walls and extends from both sides of the joint on each of the insulation blocks 31, 33. Thus, the flexible sheet partially covers the rigid sheet 131 in the corner region. The two distal portions 2311 of the flexible sheet are each bonded to a portion of the rigid sheet 131, while the central portion 2312 of the flexible sheet may be unbonded.

[0012] The arrangement described above for the pre-assembled block 80 is similarly applicable to the pre-assembled block 70 having a flexible sheet, which is the lower composite sheet 232.

[0013] The term "composite sheet" can refer to a sheet containing metallic elements. These metallic elements can be either separated and distributed within the composite sheet, or formed into a uniform layer (such as a metal sheet).

[0014] In the remainder of the specification, the term "composite sheet" may refer to either an FSB sheet or an RSB sheet. It should be remembered that, within the context of the invention described herein, the composite sheet is made of an aluminum sheet inserted between two layers of fiberglass cloth. In other words, the composite sheet includes a metal sheet, which may be an FSB sheet or an RSB sheet.

[0015] Pre-assembled blocks 70 and 80 are prefabricated. These pre-assembled components are transported to the site for installation in the tank. Two pre-assembled blocks 70 and 80 are positioned and secured within the tank. An insulation element 41 is inserted between the two pre-assembled blocks. At this stage, the pre-assembled blocks, thus stacked from the supporting structure towards the interior of the tank, comprise a series of layers: insulation blocks (31, 33 and 32, 34), rigid sheets (131 and 132), and flexible sheets (lower composite sheets 231 and 232).

[0016] To ensure the continuity of the secondary barrier, an additional flexible sheet, referred to as the upper composite sheet 133, is bonded across two adjacent flexible sheets (lower composite sheets 231, 232). It should be noted that the lower sheet located below the additional flexible sheet can be a rigid sheet (RSB). The additional flexible sheet allows for the sealing of the secondary sealing membrane between adjacent insulation blocks 31, 32, 33, 34 in the corner region. This bonding step is performed on the pre-assemblies disclosed above. This step is carried out in the field, within the tank. The bonding of the additional flexible sheet is typically done by hand, which can result in variations in the adhesive thickness between the two flexible sheets. Here, it should be understood that the adhesive thickness discussed is the thickness between the flexible sheets of the pre-assembly blocks 70 and 80 and the additional flexible sheet. Furthermore, once applied, due to gravity, the adhesive on wall 7 tends to slide towards the intersection 9 of tank walls 7, 8. This results in a thinner additional adhesive layer at the intersection 9 of the walls, and a lack of adhesive on the upper portion of the additional flexible sheet.

[0017] The corner region is a particularly stressful area due to its location between two tank walls. To withstand the thermomechanical stresses experienced by the corner region, it must be both flexible and robust. The adhesive thickness between the flexible sheet and the additional flexible sheet is a critical condition for ensuring a corner region seal. The adhesive thickness between these two flexible sheets must be between two extreme values, for example, between 0.2 mm and 1.2 mm. If the adhesive thickness does not meet this condition, there is a risk that the additional flexible sheet will rupture, resulting in a lack of seal in the corner region.

[0018] An existing solution for checking the adhesive thickness between a flexible sheet and an additional flexible sheet involves using a measuring wedge, such as a ruler. The operator positions the measuring wedge on either edge 1331 or 1332 of the additional flexible sheet 133 to measure the distance between the flexible sheet of pre-assembled block 80 or pre-assembled block 70 and the additional flexible sheet, along a direction locally perpendicular to the flexible sheet. The distance measured between the flexible sheet and the additional flexible sheet allows the adhesive thickness between the two flexible sheets to be derived. While this is generally satisfactory, the readings obtained in this manual inspection can be biased due to the measuring wedge and the operator's positioning when reading the reading. Furthermore, this measurement only provides information about the adhesive thickness around the perimeter of the additional flexible sheet. The use of this measuring wedge does not provide information about the adhesive thickness beneath the entire surface of the additional sheet (i.e., between the two edges 1331, 1332 of the additional sheet).

[0019] The present invention aims to overcome at least part of the above-mentioned disadvantages by providing an apparatus and method for inspecting the adhesive thickness between two flexible composite sheets of a tank wall, which enables the rapid, accurate and easy inspection of the adhesive thickness. Summary of the Invention

[0020] Therefore, the present invention provides a method for inspecting the adhesive thickness in an inspection area extending between an upper composite sheet and a lower composite sheet located on at least one tank wall, the inspection method comprising: -Step (also known as the first step): Position one end of the electromagnetic field emitter on the upper composite sheet, on the current portion of the inspection area, with the end of the emitter conforming to the shape of the upper composite sheet of the current portion. - Step (also known as the second step): A variable magnetic field is generated by an electromagnetic field emitter to generate an induced current flowing in the current section; - Step (also known as the third step): Receive a signal with a magnetic phase difference, which characterizes the distance between the upper composite sheet and the lower composite sheet; - Step (also known as the fourth step): Determine the adhesive thickness in the current section based on the magnetic phase difference.

[0021] Using these characteristics, the inspection method is based on generating an induced current in two composite sheets separated by the adhesive thickness. A reactive magnetic field is generated in each of the composite sheets. The inspection method uses the magnetic phase difference generated by the spacing between the two composite sheets to determine the distance between them. This distance corresponds to the adhesive thickness that the method is intended to inspect.

[0022] In other words, the use of a magnetic field allows for the non-invasive determination of the adhesive thickness that separates the two FSB sheets. The thickness is determined quickly and accurately, and can be determined in any tank wall area.

[0023] According to an optional feature of the invention, the inspection method includes the steps of: moving an end of the electromagnetic field emitter on an upper composite sheet, on a portion adjacent to the current portion, and for the adjacent portion, performing a generation step, a receiving step, and a determination step to determine the adhesive thickness of the adjacent portion.

[0024] This step allows for continuous determination of the adhesive thickness in the inspection area. In particular, the method of the present invention allows for determination of the adhesive thickness between two composite sheets, under the entire surface of the upper composite sheet, rather than just determining the adhesive thickness around the periphery of the upper composite sheet as in existing solutions.

[0025] According to an optional feature of the invention, the generating step, receiving step, and determining step are performed continuously. This means that the generating step, receiving step, and determining step are also performed during the movement of the end of the electromagnetic field emitter on the upper composite sheet. This is referred to as a linear embodiment, during which the adhesive thickness is also measured during the movement step.

[0026] According to an optional feature of the invention, the upper composite sheet and the lower composite sheet are positioned on two tank walls that intersect each other along an intersecting axis and form a tank angle between the two tank walls, during the positioning step (first step), the end of the electromagnetic field emitter is positioned on the intersecting axis.

[0027] Therefore, the adhesive thickness can be determined at the can angle, i.e., in a very localized area where excess adhesive may exist between the two sheets. As mentioned above, during the bonding step of the FSB sheets, the angle between the two walls causes the adhesive to slip due to gravity. Since this area between the two FSB sheets in the corner region is inaccessible, it is impossible to check the adhesive thickness by conventional means. By means of the method of the present invention, using a magnetic field and retrieving the resulting magnetic phase difference from the two FSB sheets makes this information accessible and allows checking whether the adhesive thickness is within the desired range.

[0028] In one embodiment of the invention, the step of moving the end of the electromagnetic field emitter along an intersecting axis is included. Multiple adhesive thicknesses are obtained by moving the emitter along the intersecting axis. This allows for the inspection of adhesive thickness over a large inspection area.

[0029] According to an optional feature of the invention, the inspection method includes a prior calibration step: designed to calibrate the magnetic phase difference based on a predetermined adhesive thickness. The predetermined adhesive thickness forms part of a database or forms part of a database.

[0030] The calibration procedure involves measuring the adhesive thickness as described above only once. In other words, in a given configuration and for multiple known adhesive thicknesses, the transmitter is positioned on the upper surface of a test inspection area that corresponds in all respects to the inspection area to be subsequently evaluated. For each adhesive thickness, the transmitter generates an electromagnetic field, thereby inducing a current. This results in two reactive magnetic fields with a magnetic phase difference. Each collected magnetic phase difference is associated with a known adhesive thickness of the configuration under test. Thus, a lookup table showing the measured magnetic phase differences and the corresponding adhesive thicknesses is obtained. Therefore, when performing the inspection method, the operator is able to determine the adhesive thickness based on the magnetic phase differences measured using the lookup table.

[0031] According to an optional feature of the invention, the inspection method includes the step of comparing the adhesive thickness determined in the determination step with a range of reference values. This comparison allows identification of whether the determined adhesive thickness meets the required standards for the inspection area.

[0032] According to an optional feature of the invention, the inspection method includes the step of: if the adhesive thickness determined in the determination step is outside the range of reference values, then a warning signal is emitted.

[0033] The present invention also relates to an apparatus for inspecting the thickness of an adhesive in an inspection area extending between an upper composite sheet and a lower composite sheet located on at least one tank wall, the apparatus comprising: - An electromagnetic field emitter, the end of which is adapted to the shape of the upper composite sheet on the current portion of the inspection area; - A current generator designed to power an electromagnetic field emitter to generate a variable magnetic field, thereby producing an induced current flowing in the current section; - An apparatus for processing signals having a magnetic phase difference characterizing the adhesive thickness, the apparatus being configured to determine the adhesive thickness in a current portion based on the magnetic phase difference.

[0034] According to an optional feature of the invention, the upper composite sheet and the lower composite sheet are positioned on two can walls that intersect each other along intersecting axes and form a can angle between the two can walls, and the end of the electromagnetic field emitter has a shape complementary to the can angle.

[0035] The complementary shapes of the transmitter's end and the tank angle ensure complete contact between the transmitter and the inspection area. This prevents measurement deviations that could be related to air located between the transmitter and the inspection area.

[0036] Furthermore, the electromagnetic field emitter may include a boot-shaped portion that forms the end of the emitter. The boot-shaped portion allows the shape of the emitter's end to be adapted to the shape of the inspection area, ensuring that the shapes of the emitter's end and the inspection area are complementary. Depending on the envisioned inspection area, the boot-shaped portion can be interchanged. Therefore, it is not necessary to replace the electromagnetic field emitter for inspection areas of different shapes.

[0037] According to an optional feature of the invention, the electromagnetic field emitter includes a positioning device that extends laterally and is intended to rest against the upper composite sheet of the current portion on both sides of the electromagnetic field emitter.

[0038] The positioning device allows for satisfactory positioning of the transmitter relative to the inspection area and relative to the tank wall. The complementary shapes of the positioning device and the transmitter's ends together ensure that the operator does not introduce measurement deviations. The transmitter remains in a stable reference position. This feature contributes to achieving high-precision and rapid measurements. Attached Figure Description

[0039] Other features and advantages of the invention will become more apparent from the following description and from several exemplary embodiments provided in a non-limiting manner with reference to the accompanying drawings, in which: [ Figure 1 This schematically illustrates a cross-sectional view of the wall of a tank known from the prior art for transporting and / or storing liquefied gases. [ Figure 2 This schematically illustrates the corner region of the can at the intersection of the two can walls during assembly in the prior art. [ Figure 3 A flowchart illustrating the steps of a method for checking adhesive thickness according to the present invention is shown. [ Figure 4 The principle of generating induced current used in the inspection method of the present invention is illustrated schematically. [ Figure 5 An embodiment of an electromagnetic field emitter for an apparatus for inspecting adhesive thickness according to the present invention is schematically shown. [ Figure 6 An exemplary embodiment of a method for checking the adhesive thickness between two FSB sheets is schematically illustrated. [ Figure 7 This schematically illustrates another exemplary embodiment of a method for checking the adhesive thickness between two FSB sheets. Detailed Implementation

[0040] The features, variations, and different embodiments of the invention disclosed above or in the detailed description below can be associated with each other in various combinations, provided that these features, variations, and different embodiments are not incompatible or mutually exclusive. In particular, variations of the invention may be conceived if the selection of features is sufficient to provide a technical advantage and / or distinguish the invention from the prior art; such variations include only the selection of the features described below (independent of the other features described).

[0041] For clarity, the same elements are represented by the same reference numerals in different figures.

[0042] Figure 1 A schematic cross-sectional view of the wall of a tank for transporting and / or storing liquefied gases, as known from the prior art, is shown. Figure 2 The diagram schematically illustrates the corner region of the can at the intersection of two can walls during assembly in the prior art. The walls are described in the background section to provide context for methods used to check the adhesive thickness between two FSB sheets.

[0043] Figure 3 A flowchart illustrating the steps of a method for checking adhesive thickness according to the present invention is shown. Although Figure 3 There are no figure labels in the document, but readers can refer to them. Figures 4 to 7 The reference numerals mentioned in the figures are intended to indicate the thickness 60 of the adhesive. The method for inspecting the adhesive thickness 60 is carried out in an inspection area extending between an upper composite sheet 133 and a lower composite sheet 231 located on at least one tank wall 7, 8. The inspection method of the present invention aims to determine the adhesive thickness 60 between the two composite sheets 231, 133. The upper and lower composite sheets are two FSB sheets as disclosed in the background art.

[0044] According to the present invention, the inspection method includes step 100: positioning one end 66 of the electromagnetic field emitter 65 on the upper composite sheet 133, on the current portion Pi of the inspection area. The inspection area may be, for example, the upper composite sheet 133 ( Figure 2 The width (between edge 1331 and edge 1332 shown in the figure). On the current section Pi, it means that the transmitter 65 is positioned facing the inspection area which is determined to be part of the current section Pi. Therefore, the inspection area can be formed by a series of current sections (which will be represented as Pi-1, Pi, Pi+1).

[0045] The end 66 of the transmitter 65 is shaped to fit the upper composite sheet 133 of the current section. This allows the transmitter to adapt to the tank angle when an inspection is performed at the joint between the two walls.

[0046] The inspection method includes step 200: generating a variable magnetic field via an electromagnetic field emitter 65 to produce induced currents flowing in the current portion Pi. These induced currents generate a reactive magnetic field, which serves as the basis for determining the adhesive thickness. This aspect will be described in detail below.

[0047] Then, the inspection method includes step 300: receiving a signal 69 having a magnetic phase difference 61, which characterizes the distance 60 between the upper composite sheet 133 and the lower composite sheet 231.

[0048] The inspection method also includes step 400: determining the adhesive thickness 60 in the current portion Pi based on the magnetic phase difference 61.

[0049] This invention is based on generating a current induced by an external current in a conductive material. The inspection method according to the invention utilizes the presence of two FSB sheets 133, 231, each FSB sheet containing a metal layer, particularly an aluminum layer. Therefore, when a sinusoidal voltage is supplied to an electromagnetic field transmitter 65, the transmitter 65 generates an electromagnetic field. An induced current forms and flows in the current portion Pi, in each metal layer of the FSB sheets 133, 231. A reactive magnetic field is generated for each metal layer. The difference between the reactive magnetic fields is generated by the two layers (i.e., the metal layer of FSB sheet 231 and the metal layer of FSB sheet 133). This difference, or magnetic phase difference, depends on the distance between the two FSB sheets 231, 133. In other words, the distance between the two FSB sheets 133, 231, i.e., the adhesive thickness 60 between the two FSB sheets, can be determined by means of the magnetic phase difference received in step 300. The thickness is determined by compiling a database of the corresponding magnetic phase differences and distances between the two composite sheets.

[0050] The phenomena that occur in the inspection method of the present invention are described in detail below.

[0051] Figure 4 The principle of generating induced current used in this invention is schematically illustrated to determine the adhesive thickness between two FSB sheets 231, 133. Allowing induced current to flow through a conductive material is a non-destructive inspection technique. This technique involves using an electromagnetic field emitter 65, such as a coil or magnetic rod, to which a sinusoidal voltage U is supplied by a voltage generator 67.

[0052] Near the object to be inspected, an electromagnetic field emitter emits a magnetic field Bi. This induces eddy currents in the conductive material and generates a reactive magnetic field within the material.

[0053] In the context of this invention, the inspection area comprises two FSB sheets 133 and 231, one on top of the other and spaced apart from each other by a determined distance. In other words, two layers of conductive material are stacked together at a given distance 60. An electromagnetic field emitter 65 emits a magnetic field Bi, inducing eddy currents in the two FSB sheets 133 and 231. For each of the FSB sheets 133 and 231, a reactive magnetic field is generated (Br1 for the upper FSB sheet 133 and Br2 for the lower FSB sheet 231). A processing device 68 retrieves signals 69 from the two magnetic fields Br1 and Br2. These signals 69 have a magnetic phase difference characteristic of the adhesive thickness 60. In a variation, the electromagnetic field emitter can be used as an electromagnetic field sensor by measuring the magnetic field.

[0054] As is well known, the distribution of induced current depends on several parameters, such as the frequency of the sinusoidal voltage supplied to the electromagnetic transmitter, the geometry of the object, the characteristics of the electromagnetic transmitter (e.g., the geometry and number of turns of the electromagnetic transmitter), the amplitude of the supplied voltage, and the distance between the transmitter and the object under inspection.

[0055] During the inspection method of the present invention, all these parameters remain constant. The only difference is the distance between the electromagnetic emitter and the FSB sheet: the electromagnetic field emitter 65 is arranged to contact the upper FSB sheet 133, and the electromagnetic field emitter 65 is located at a given distance from the lower FSB sheet 231, which corresponds to the adhesive thickness 60 to be inspected. Due to this distance between the two FSB sheets, a magnetic phase difference is observed. This magnetic phase difference is directly related to the distance between the two FSB sheets 231, 133.

[0056] Therefore, the present invention can determine the distance between two composite sheets by reading the magnetic phase difference.

[0057] Advantageously, the inspection method of the present invention includes a prior calibration step 90: designed to calibrate the magnetic phase difference according to a predetermined adhesive thickness.

[0058] During this calibration step, steps 100, 200, and 300 are performed on the wall of the so-called test tank. All operating conditions are identical to the actual scenario in which the inspection method will subsequently be implemented. The FSB sheets in the so-called test tank are the same as sheets 133 and 231, and the adhesive used between the two FSB sheets is the same adhesive that will be applied between sheets 133 and 231 under the actual conditions in the tank. With all parameters identical, a series of measurements are performed on the different known adhesive thicknesses between the two FSB sheets 133 and 231. Preferably, the reference value for the adhesive thickness ranges from 0.2 mm to 1.2 mm. For each adhesive thickness, the resulting magnetic phase difference is stored. Thus, calibration step 90 can obtain a table of magnetic phase differences based on the adhesive thickness between the two FSB sheets. This calibration step is performed only once, such that the adhesive thickness separating the two FSB sheets 231 and 133 can be correlated with the measured magnetic phase difference.

[0059] exist Figure 4 In this invention, the underlying principle is applied to flat walls. However, as explained in the background section, the inspection area that is particularly important for inspection is the corner region between two walls, which forms an angle A between the two walls, which can be, in particular, 90° or 135°. In the intersecting region, the two walls 7, 8 are along the intersecting axis 9 (e.g., Figure 5The two walls (as shown) intersect each other, forming a can angle A between them. Each FSB sheet has a fold in this intersection region, which sends a different response in terms of the reactive magnetic field than the flat FSB sheet. Therefore, calibration step 90 must also be performed when checking the adhesive thickness at can angle A. Thus, if the adhesive thickness between the two FSB sheets is to be checked on the flat wall and in the can angle region (e.g., 90°) between the two walls, calibration step 90 must first be performed once on the flat wall and once at the 90° can angle. For each wall configuration (flat or forming an angle between the two walls), calibration step 90 can obtain a series of magnetic phase difference values, each corresponding to the distance between the two FSB sheets (i.e., the adhesive thickness between the two FSB sheets).

[0060] Figure 5 An embodiment of an electromagnetic field emitter 65 of an apparatus 1000 for inspecting adhesive thickness 60 according to the present invention is schematically illustrated. In this illustration, the can angle (i.e., the angle formed by the two walls 7, 8 at their intersection) is 135°. The inspection area is located at the intersection 9 of the two walls 7, 8. Therefore, the purpose is to inspect the adhesive thickness between the two FSB sheets 231, 133 at the intersection 9. Two current sections (Pi-1 and Pi) are shown. It can be seen that the end 66 of the emitter 65 is adapted to the shape of the upper composite sheet 133 of the current section. This means that the end 66 of the emitter 65 forms a 135° angle to adapt to the can angle between the walls 7, 8. The complementary shapes of the end 66 of the emitter 65 and the upper surface of the inspection area allow the end 66 to make full contact with the upper surface of the inspection area. This makes it possible to avoid measurement drift, which could be caused by airflow between the end 66 of the emitter 65 and the upper surface of the area to be inspected.

[0061] According to an optional feature of the invention, the electromagnetic field emitter 65 includes a boot-shaped portion forming an end 66 of the emitter 65. The boot-shaped portion 661 has two ends. A first end of the boot-shaped portion 661 is connected to the lower end of the emitter 65. A second end of the boot-shaped portion 661 has a shape complementary to the upper surface of the inspection area. The second end of the boot-shaped portion 661 is flat to inspect the adhesive thickness between two FSB sheets of a flat wall. The second end of the boot-shaped portion 661 has a shape complementary to angle A to inspect the adhesive thickness between two FSB sheets forming an angular region. Therefore, the second end of the boot-shaped portion 661 is securely positioned within the can angle. The second end of the boot-shaped portion 661 is coplanar with two planes formed by the two walls 7 and 8.

[0062] In addition to ensuring accurate measurements, the complementary shape of the end 66 of the transmitter 65 helps facilitate the movement of the transmitter 65 along the inspection area.

[0063] The boot-shaped part 661 can be made of plastic (such as polytetrafluoroethylene (often abbreviated as PTFE)), steel, or any other alloy or composite material.

[0064] It should be noted that calibration step 90 must be performed in the envisioned measurement configuration. This means that in order to check the adhesive thickness between two FSB sheets at can angle A using a transmitter including a PTFE boot, a calibration step must first be performed in the same configuration (with the same can angle A and the same PTFE boot).

[0065] According to an optional feature of the invention, the electromagnetic field emitter 65 includes positioning devices 662 that extend laterally and are intended to rest against the upper composite sheet 133 of the current portion Pi on both sides of the electromagnetic field emitter 65. The positioning devices 662 may be a pair of rods extending from the central body 663 of the emitter, located on both sides of the central body 663, advantageously symmetrical with respect to the central body 663, with the ends of the rods resting against the upper surface of the inspection area. Therefore, it should be understood that the length of the rods depends on the can angle A. Depending on the shape of the emitter 65, the emitter may include multiple pairs of rods distributed on both sides of the central body 663 of the emitter 65.

[0066] The positioning device 662 facilitates the positioning of the transmitter 65 relative to the walls 7, 8 and maintains that position during measurement. Therefore, the positioning device defines a stable reference position for the transmitter 65. Furthermore, the positioning device 662 prevents any risk of the transmitter 65 tilting during manipulation. This positioning device forms a guide for the transmitter 65 along the inspection area. Combined with the complementary shape of the end 66 of the transmitter 65, the positioning device 662 allows the transmitter 65 to be securely positioned on the inspection area in a single orientation relative to the walls. The complementary shapes of the positioning device 662 and the end 66 of the transmitter 65 eliminate the influence of the operator, as the transmitter 65 is always positioned in its stable reference position. This results in high-precision measurements, in addition to the speed of moving and positioning the transmitter 65.

[0067] Figure 6An exemplary embodiment of a method for inspecting the adhesive thickness between two FSB sheets is schematically illustrated. In this stage of the inspection method, calibration step 90 is first performed once on a test inspection area having the same can angle (135° in this case), the same transmitter 65, and operating conditions identical to the actual inspection scenario. Therefore, the operator can access a lookup table indicating the magnetic phase difference observed during the calibration step and the corresponding adhesive thickness between the two FSB sheets.

[0068] The transmitter end 66 is positioned on the upper FSB sheet 133, on the current portion Pi in the inspection area. The current portion Pi is located at the intersection 9 between the two walls 7 and 8. The end 66 of the transmitter 65 matches the shape of the upper composite sheet 133 of the current portion. It should be understood that, Figure 6 In the example, the transmitter 65 has an end 66 tilted at an angle of 135°.

[0069] Figure 7 Another exemplary embodiment of a method for checking the adhesive thickness between two FSB sheets is schematically illustrated. In this example, the emitter 65 is U-shaped, wherein two portions contact the upper surface of the FSB sheet 133. In effect, these two portions form the ends of the emitter, which are adapted to the shape of the FSB sheet 133.

[0070] It should be noted that this is a non-limiting example. The invention is applicable to electromagnetic transmitters of any shape, wherein one end of the transmitter has a shape complementary to the inspection area to be inspected.

[0071] The inspection device 1000 of the present invention also includes a current generator 67 for supplying power to the electromagnetic field emitter 65. After current is supplied to the emitter 65, a variable magnetic field is generated, and an induced current flows in the current portion Pi.

[0072] Below the transmitter 65, two FSB sheets 133 and 231 are positioned one on top of the other and separated by adhesive thickness. Since each FSB sheet includes a thin metal layer, induced current flows in a portion Pi of each of the two FSB sheets. For each FSB sheet 133 and 231, a reactive magnetic field is generated. Sheet 231 is further away from the transmitter 65 than sheet 133. Sheet 231 observes the magnetic field generated by the transmitter 65 with an offset compared to sheet 133. This results in a phase difference between the two generated magnetic fields, based on which the distance between the two sheets 133 and 231 is determined.

[0073] The inspection apparatus 1000 of the present invention includes means 68 for processing a signal 69 having a magnetic phase difference 61 characterizing an adhesive thickness 60. The processing means 68 can determine the adhesive thickness 60 in a current portion Pi based on the measured magnetic phase difference 61. As an example, the processing means 68 may include an oscilloscope that directly displays the measured magnetic phase difference corresponding to the adhesive thickness between two FSB sheets. Alternatively, the processing means 68 may include a display screen that displays the adhesive thickness value after reading a lookup table showing the adhesive thickness and the corresponding magnetic phase difference established in calibration step 90.

[0074] Following steps 100, 200, 300, and 400, i.e., after the adhesive thickness for portion Pi has been determined, the inspection method of the present invention may include step 500: moving the end 66 of the electromagnetic field emitter 65 on the upper composite sheet 133, on portion Pi+1 adjacent to the current portion Pi. By means of the specific shape of the emitter end 66 and the positioning device 662 (if applicable), the emitter 65 can be easily translated along the inspection area to assess the adhesive thickness in the portion adjacent to the portion just assessed.

[0075] It should be noted that, Figure 7 In the diagram, portion Pi+1 is offset from portion Pi. The portion adjacent to portion Pi (the portion between portion Pi and Pi+1 in the figure) does not have two FSB sheets. Insulation block 41 is located below sheet 133. Adhesive thickness measurement is not required for this portion.

[0076] Once the transmitter 65 is positioned on the new current portion Pi+1, for that portion Pi+1, a second step 200, a third step 300, and a fourth step 400 are performed, namely a positioning step, a generating step, a receiving step, and a determining step, to determine the adhesive thickness 60 of that portion Pi+1. By proceeding stepwise in this manner, the adhesive thickness between the two FSB sheets 133, 231 can be determined along the inspection area. As mentioned above, the inspection area relates to the width of sheet 133. However, the same principle of the invention can be applied to the length of sheet 133, in which case the transmitter 65 is positioned on a flat wall (it will be understood that, in this configuration, the end 66 of the transmitter 65 is flat).

[0077] According to an optional feature of the invention, the generating step 200, the receiving step 300, and the determining step 400 are performed sequentially, regardless of the positioning of the transmitter 65 on the sheet. This means that steps 200, 300, and 400 are also performed during the moving step 500. Steps 200, 300, and 400 are performed sequentially during the movement of the transmitter 65. This allows the adhesive thickness to be determined linearly.

[0078] According to an optional feature of the invention, the inspection method may include step 450: comparing the adhesive thickness determined in step 400 (or the fourth step) with a range of reference values. For example, the range of reference values ​​may be set between 0.2 mm and 1.2 mm. The operator checks whether the determined adhesive thickness is within the range. This value may be displayed by the processing device 68, in which case the operator directly compares these values. Alternatively, if the processing device 68 indicates a magnetic phase difference value, the operator may compare this value with a value shown in a lookup table generated by the calibration step to identify whether the determined adhesive thickness is within the desired range.

[0079] According to an optional feature of the invention, the inspection method may include step 460: if the adhesive thickness 60 determined in step 400 is outside the range of a reference value, then a warning signal is emitted. The warning signal may be a visual or audible signal that draws the operator's attention to the lack or excess of adhesive in the inspection area.

[0080] Of course, the present invention is not limited to the examples just described, and many changes can be made to these examples without departing from the scope of the invention. In particular, features of different variations of the invention can be combined to implement the invention, provided that these variations are not incompatible with each other.

Claims

1. A method for inspecting the thickness (60) of an adhesive in an inspection area extending between an upper composite sheet (133) and a lower composite sheet (231) located on at least one tank wall (7, 8), the inspection method comprising: - Step (100): Position one end (66) of the electromagnetic field emitter (65) on the upper composite sheet (133) and on the current portion (Pi) of the inspection area, wherein the end (66) of the electromagnetic field emitter (65) is adapted to the shape of the upper composite sheet (133) of the current portion; - Step (200): A variable magnetic field is generated by the electromagnetic field emitter (65) to generate an induced current flowing in the current section (Pi); - Step (300): Receive a signal (69) having a magnetic phase difference (61), the magnetic phase difference representing the distance (60) between the upper composite sheet (133) and the lower composite sheet (231). - Step (400): Determine the adhesive thickness (60) in the current portion (Pi) based on the magnetic phase difference (61).

2. The inspection method according to claim 1, comprising the steps (500): moving the end (66) of the electromagnetic field emitter (65) on the upper composite sheet (133) on a portion (Pi+1) adjacent to the current portion (Pi), and for the adjacent portion (Pi+1), performing a generation step (200), a receiving step (300), and a determination step (400) to determine the adhesive thickness (60) of the adjacent portion (Pi+1).

3. The inspection method according to claim 2, wherein, The generation step (200), the receiving step (300), and the determination step (400) are performed consecutively.

4. The inspection method according to any one of claims 1 to 3, wherein, The upper composite sheet (133) and the lower composite sheet (231) are positioned on two tank walls (7, 8) that intersect each other along an intersecting axis (9) and form a tank angle (A) between the two tank walls. During the positioning step (100), the end (66) of the electromagnetic field emitter (65) is positioned on the intersecting axis (9).

5. The inspection method according to claim 4 in conjunction with claim 2 or 3, wherein, The step (500) involves moving the end (66) of the electromagnetic field emitter (65) along the intersecting axis (9).

6. The inspection method according to any one of claims 1 to 5, comprising a prior calibration step (90): designed to calibrate the magnetic phase difference according to a predetermined adhesive thickness.

7. The inspection method according to any one of claims 1 to 6, comprising the step (450): comparing the adhesive thickness determined in step (400) with a range of reference values.

8. The inspection method according to claim 7, comprising the step (460): if the adhesive thickness (60) determined in the determining step (400) is outside the range of a reference value, then a warning signal is emitted.

9. An apparatus (1000) for inspecting the thickness (60) of an adhesive in an inspection area extending between an upper composite sheet (133) and a lower composite sheet (231) located on at least one tank wall (7, 8), the inspection apparatus comprising: - Electromagnetic field emitter (65), the end (66) of which is adapted to the shape of the upper composite sheet (133) on the current portion (Pi) of the inspection area; - Current generator (67), which is designed to power the electromagnetic field emitter (65) to generate a variable magnetic field, thereby generating an induced current flowing in the current section (Pi); - A device (68) for processing a signal (69) having a magnetic phase difference (61) characterizing an adhesive thickness (60), the device (68) being configured to determine the adhesive thickness (60) in the current portion (Pi) based on the magnetic phase difference (61).

10. The inspection device (1000) according to claim 9, wherein the upper composite sheet (133) and the lower composite sheet (231) are positioned on two tank walls (7, 8), the two tank walls intersecting each other along intersecting axes (9) and forming a tank angle (A) between the two tank walls, wherein, The end (66) of the electromagnetic field emitter (65) has a shape complementary to the tank angle (A).

11. The inspection device (1000) according to claim 9 or 10, wherein, The electromagnetic field emitter (65) includes a boot-shaped portion (661) that forms the end portion (66) of the electromagnetic field emitter (65).

12. The inspection device (1000) according to any one of claims 9 to 11, wherein, The electromagnetic field emitter (65) includes a positioning device (662) that extends laterally and is intended to rest on the upper composite sheet (133) of the current portion (Pi) on both sides of the electromagnetic field emitter (65).

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