Three-layer stainless steel container inner layer plate thickness transient electromagnetic testing device and method

Abstract

The invention discloses a transient electromagnetic testing device and method for the thickness of an inner plate of a three-layer stainless steel container, and belongs to the technical field of nondestructive testing of special equipment. According to the technical scheme, the transient electromagnetic testing device for the thickness of the inner plate of the three-layer stainless steel container comprises a T-shaped frame, a height adjusting assembly and a fixing assembly; the T-shaped frame is formed by vertically connecting a vertical plate and a bottom plate, the vertical plate is provided with at least one height adjusting groove, and the edge of the height adjusting groove is provided with scale marks; the fixing assembly comprises a bolt and a nut, the bolt can move along the height adjusting groove, and the nut is matched with the bolt to support and fix the outer-layer steel plate and the middle-layer steel plate in the three layers of stainless steel; according to the invention, the distance between three layers of steel plates can be accurately controlled through the height-adjustable structure of the T-shaped frame, multi-layer interference components in transient electromagnetic signals are effectively separated by combining specific time window selection and correction coefficient matching algorithms, and the technical effects of realizing non-contact accurate detection of the thickness of the inner layer and avoiding shutdown and can opening of equipment are achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of non-destructive testing of special equipment, and particularly relates to a three-layer stainless steel container inner layer plate thickness transient electromagnetic testing device and method. BACKGROUND

[0002] In the field of special equipment detection, the transient electromagnetic detection technology has achieved certain application results in single-layer metal structure thickness detection due to its non-contact measurement characteristics. However, the technology has significant limitations when facing multi-layer composite structure containers, especially for stainless steel containers with an outer protective layer, a jacket layer and an inner cylinder layer. The existing technology cannot effectively detect the thickness of the inner layer steel plate. The three-layer stainless steel structure used in medical inactivated containers and other special equipment directly contacts the corrosive medium, and the thickness change directly affects the safety performance of the equipment. However, due to the complexity of the structure, conventional detection methods all have implementation obstacles.

[0003] The traditional ultrasonic detection method can only measure the thickness of the outermost steel plate. If the inner layer needs to be detected, the probe must be inserted into the container, which is completely inoperable in closed containers or equipment containing hazardous media. Although the pulse eddy current technology can penetrate the insulation layer, it has insufficient resolution for the multi-layer structure of the jacket type equipment, and cannot accurately identify the inner layer steel plate signal. The existing transient electromagnetic detection device only considers the single-layer metal detection requirement in the design, and the probe lift-off distance is fixed and the support structure is single, which cannot adapt to the adjustment requirement of different spacings of the three-layer steel plate, resulting in mutual interference of the detection signal and inability to extract effective inner layer thickness characteristic parameters.

[0004] If the medical inactivated container and other industrial equipment use the shutdown and open tank detection method, not only will it cause production interruption and economic loss, but also there is a safety risk of contacting residual toxins. There is a lack of solutions in the current market that can simultaneously meet the three-layer structure adaptability, detection accuracy and operation safety, resulting in a long-term technical blank in the detection of the inner layer thickness of such equipment. The wide application of multi-layer stainless steel containers in the fields of nuclear power, chemical industry and other fields makes it an urgent need to develop special detection devices and methods to ensure the safe operation of the equipment. SUMMARY

[0005] The purpose of the present application is to provide a three-layer stainless steel container inner layer plate thickness transient electromagnetic testing device and method, which has the advantages of realizing accurate adjustment of the spacing of the three-layer steel plate and improving the separation degree and detection accuracy of the transient electromagnetic signal.

[0006] The application provides a three-layer stainless steel container inner layer plate thickness transient electromagnetic testing device, and the technical scheme is as follows: a three-layer stainless steel container inner layer plate thickness transient electromagnetic testing device, comprising a T-shaped frame, a height adjusting assembly and a fixing assembly; the T-shaped frame is composed of a vertical connection of a vertical plate and a bottom plate, at least one height adjusting groove is arranged on the vertical plate, and a scale mark is arranged on the edge of the height adjusting groove; the fixing assembly comprises a bolt and a nut, the bolt is movable along the height adjusting groove, and the nut is matched with the bolt to support and fix the outer layer steel plate and the middle layer steel plate in the three-layer stainless steel; the bottom plate is used for directly supporting the inner layer steel plate in the three-layer stainless steel, so that the inner layer steel plate forms an adjustable spacing with the outer layer steel plate and the middle layer steel plate.

[0007] Further, the application also provides that two parallel height adjusting grooves are arranged on the vertical plate, and the two height adjusting grooves correspond to the bolt mounting positions for supporting the outer layer steel plate and the middle layer steel plate respectively.

[0008] Further, the application also provides that the vertical plate and the bottom plate are connected through an angle weld to form an integrated T-shaped frame structure.

[0009] Further, the application also provides that the nut is a plurality of nuts, and the plurality of nuts are stacked on the bolt to increase the contact support area with the outer layer steel plate or the middle layer steel plate.

[0010] Further, the application also provides that the heat preservation material is filled between the outer layer steel plate and the middle layer steel plate and between the middle layer steel plate and the inner layer steel plate.

[0011] Further, the application also provides a three-layer stainless steel container inner layer plate thickness transient electromagnetic testing method, comprising the following steps: S1, adjusting the interlayer spacing of the outer layer steel plate, the middle layer steel plate and the inner layer steel plate according to the design parameters of the three-layer stainless steel container through the above testing device; S2, collecting signals of the adjusted three-layer steel plate by using the transient electromagnetic technology, and obtaining a transient electromagnetic attenuation curve; S3, taking a preset point before a third inflection point of the attenuation curve as a starting point of a time window, and selecting a preset number of points as a time window interval; S4, calculating a measured value of the inner layer steel plate thickness based on the signal data in the time window interval, and selecting a corresponding correction coefficient for error correction according to the measured thinning rate of the inner layer steel plate to obtain a final value of the inner layer plate thickness.

[0012] Further, in step 3, the preset point before the third inflection point is two points before the third inflection point, and the time window interval is an interval formed by selecting three points from the starting point.

[0013] Further, the application also proposes that the corresponding relationship between the measured thinning rate and the correction coefficient in step 4 is: when the measured thinning rate is less than or equal to 5%, the correction coefficient is 1.0; when the measured thinning rate is 10%-20%, the correction coefficient is 1.3; when the measured thinning rate is 20%-30%, the correction coefficient is 1.6; and when the measured thinning rate is 30%-40%, the correction coefficient is 1.9.

[0014] Further, the application also proposes that the design parameters in step 1 include the outer layer steel plate thickness, the middle layer steel plate thickness, the inner layer steel plate reference thickness, the outer layer-middle layer spacing, and the middle layer-inner layer spacing.

[0015] Further, the application also proposes that when the testing device is adjusted in step 1, the inner layer steel plate is directly placed on the bottom plate of the T-shaped frame, and the outer layer steel plate and the middle layer steel plate are fixed at the height adjustment groove of the vertical plate through the cooperation of the bolt and the nut.

[0016] As can be seen from the above, the three-layer stainless steel container inner layer plate thickness transient electromagnetic testing device and method provided by the application realizes accurate control of the spacing between the three-layer steel plates through the adjustable height structure of the T-shaped frame, effectively separates the multi-layer interference components in the transient electromagnetic signal by combining the specific time window selection and the correction coefficient matching algorithm, and has the technical effects of realizing non-contact inner layer thickness accurate detection and avoiding equipment downtime and tank opening. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a perspective view of the testing device proposed by the application; Figure 2 It is a side view of the testing device proposed by the application; Figure 3 It is a front view of the testing device proposed by the application; Figure 4 It is one of the test method block diagrams proposed by the application; Figure 5 It is the second test method block diagram proposed by the application.

[0018] The drawings described herein are used to provide further understanding of the application, and form a part of the application. The schematic embodiments of the application and their descriptions are used to explain the application, and do not constitute an improper limitation on the application.

[0019] In the drawings: 1, T-shaped frame; 11, vertical plate; 12, bottom plate; 2, height adjustment groove; 21, scale mark; 3, bolt; 31, nut; 4, inner layer steel plate; 5, middle layer steel plate; 6, outer layer steel plate. DETAILED DESCRIPTION

[0020] In order to more clearly illustrate the overall technical solutions of the present application, the following will be given in detail with reference to the accompanying drawings.

[0021] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced without the specific details. In other instances, well-known methods have not been described in detail in order not to unnecessarily obscure aspects of the present application.

[0022] In addition, in the description of the present application, it should be understood that the terms "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0023] In the present application, unless specifically defined and limited otherwise, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, they can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection, or communication; can be directly connected, or indirectly connected through intermediate medium, or internal communication of two elements or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0024] In the present application, unless specifically defined and limited otherwise, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. In the description of the present application, the description of the terms "embodiment", "example", "one embodiment", "example" or "specific example" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0025] In the prior art, although the transient electromagnetic detection technology can be used for non-invasive thickness measurement of single-layer steel plate, the existing device cannot adjust the spacing between the layers when facing a three-layer stainless steel container, resulting in insufficient thickness detection precision of the inner layer. Medical inactivated containers and other special equipment need to measure the thickness of the inner layer without damaging the structure. The existing detection tools lack the function of adjusting the layer spacing and cannot adapt to the characteristics of multi-layer structure, resulting in increased signal acquisition error.

[0026] In order to solve the above problems, a detection device capable of accurately controlling the spacing of the three-layer steel plate needs to be developed. The existing detection method cannot realize the interlayer spacing adaptation through external adjustment, resulting in the transient electromagnetic signal being disturbed by the adjacent steel plate. Through analysis, it is found that if the spacing of each layer can be kept consistent with the design parameters during detection, the signal superposition effect can be effectively eliminated. Based on this, a support structure with height adjustment function needs to be built, so that the positions of the outer and middle steel plates are adjustable, while the position of the inner steel plate is fixed, forming a stable detection environment.

[0027] Therefore, with reference to Figures 1-3 , the present application proposes a three-layer stainless steel container inner plate thickness transient electromagnetic testing device including a T-shaped bracket 1, a height adjustment assembly, and a fixing assembly. The T-shaped bracket 1 is composed of a vertical connection of a vertical plate 11 and a bottom plate 12, at least one height adjustment groove 2 is provided on the vertical plate 11, and a scale mark 21 is provided on the edge of the height adjustment groove 2. The fixing assembly includes a bolt 3 and a nut 31, the bolt 3 can move along the height adjustment groove 2, and the nut 31 cooperates with the bolt 3 to support and fix the outer steel plate 6 and the middle steel plate 5. The bottom plate 12 is used to directly support the inner steel plate 4, so that the inner steel plate 4 forms an adjustable spacing with the outer steel plate 6 and the middle steel plate 5.

[0028] Among them, the T-shaped bracket 1 is a support structure formed by the vertical connection of the vertical plate 11 and the bottom plate 12, which can be realized by welding process, for example, through fillet welding to form an integrated structure to ensure overall rigidity. The height adjustment groove 2 is a longitudinal slot opened on the vertical plate 11, which can be formed by machining, for example, milling, to limit the movement range of the bolt 3 by the length of the groove body. The scale mark 21 is a linear scale marked on the edge of the height adjustment groove 2, which can be realized by laser engraving process, for example, marking the value in millimeters, to assist in positioning the installation height of the bolt 3. The bolt 3 and the nut 31 are fasteners for clamping the steel plate, which can be made of stainless steel, for example, the nut 31 is stacked on the rod body of the bolt 3 to increase the contact area with the steel plate. The bottom plate 12 is a horizontal bearing platform, which can be processed from a rectangular steel plate, for example, surface polishing to reduce the frictional resistance with the inner steel plate 4.

[0029] Specifically, during detection, the inner steel plate 4 is first placed flat on the surface of the bottom plate 12, and then the height of the outer and middle steel plates 5 is adjusted according to the design parameters. The operator determines the target position of the bolt 3 in the height adjustment groove 2 through the scale mark 21, moves the bolt 3 to the corresponding scale line, and then tightens the nut 31 to fix the outer and middle steel plates 5 at the specified height. By adjusting the positions of different bolts 3, the spacing of each layer can be accurately controlled to be consistent with the actual structural parameters of the container. The transient electromagnetic probe collects signals above the adjusted multi-layer steel plate, and since the interlayer spacing matches the design value, the interference components in the detection signal are significantly reduced, thereby accurately reflecting the thickness of the inner steel plate 4.

[0030] Compared with the prior art, the existing detection device only supports single-layer steel plate fixation and cannot adapt to multi-layer structure, resulting in signal interference by adjacent layers. The scheme realizes accurate control of the spacing between three layers of steel plates through an adjustable support structure, eliminates the influence of multi-layer superposition effect, and avoids invasive operation, thereby ensuring detection safety.

[0031] Through the above technical scheme, the present application can complete accurate detection of the thickness of the inner layer plate of a three-layer stainless steel container in a non-destructive state, without the need for shutdown or opening of the container, effectively avoiding the risk of toxin leakage. By adjusting the interlayer spacing to be consistent with the design parameters, signal interference is reduced, and the accuracy of thickness calculation is improved, which is particularly suitable for medical inactivated containers and other scenarios that require strict safety and detection accuracy.

[0032] Referring to Figures 1-3 The present application further provides that the vertical plate 11 is provided with two parallel height adjustment grooves 2, and the two height adjustment grooves 2 correspond to the bolt 3 mounting positions of the outer layer steel plate 6 and the middle layer steel plate 5, respectively.

[0033] The height adjustment groove 2 is a strip-shaped through hole provided on the vertical plate 11 for adjusting the bolt 3 mounting position, which can specifically form a longitudinal groove body with scale marks 21 on the surface of the vertical plate 11 by machining, and the lifting displacement of the bolt 3 can be directly read through the scale marks 21. The two parallel height adjustment grooves 2 are two mutually parallel strip grooves provided on the surface of the vertical plate 11, which can specifically maintain the parallelism and spacing accuracy of the two groove bodies through numerical control cutting process, and the two groove bodies correspond to the support positions of the outer layer steel plate 6 and the middle layer steel plate 5, respectively, so that the spacing adjustment between the steel plates has independent operation space. The bolt 3 mounting position is the position where the bolt 3 forms a fixed point with the nut 31 after passing through the height adjustment groove 2, which can specifically be positioned at different heights by moving the bolt 3 in the height adjustment groove 2 and locking the nut 31, and the independent setting of the two height adjustment grooves 2 makes the spacing adjustment of the outer layer steel plate 6 and the middle layer steel plate 5 not interfere with each other.

[0034] Specifically, two parallel height adjustment grooves 2 are machined on the surface of the vertical plate 11, and the two groove bodies correspond to the support requirements of the outer layer steel plate 6 and the middle layer steel plate 5, respectively. During operation, the bolt 3 corresponding to the outer layer steel plate 6 is moved along the first height adjustment groove 2 to the target scale position, and the support point of the outer layer steel plate 6 is formed by locking the nut 31; the bolt 3 corresponding to the middle layer steel plate 5 is independently moved along the second height adjustment groove 2 to another scale position, and the support point of the middle layer steel plate 5 is formed by locking the nut 31. The parallel layout of the two groove bodies makes the spacing adjustment process of the outer layer steel plate 6 and the middle layer steel plate 5 not interfere with each other, and the support points of the outer layer steel plate 6 and the middle layer steel plate 5 can be independently positioned according to the design parameters, respectively, to ensure accurate control of the spacing between the steel plates.

[0035] The application realizes the separation control of the support points of the outer steel plate 6 and the middle steel plate 5 by arranging two parallel height adjustment grooves 2. The parallel double-groove structure of the application can eliminate the mutual influence of the adjustment actions of different layers of steel plates, and improve the stability and repeatability of the spacing control.

[0036] Through the above technical solution, the application can realize independent adjustment of the support height of the outer steel plate 6 and the middle steel plate 5, avoid the position interference problem in the spacing adjustment process of multiple layers of steel plates, and ensure that the spacing between the layers of steel plates is accurately matched with the design parameters. The separation design of the two parallel height adjustment grooves 2 simplifies the operation process, and the operator can quickly position the outer and middle steel plates 5 respectively, effectively improving the adjustment efficiency and test accuracy of the detection device.

[0037] With reference to Figures 1-3 The application further proposes that the vertical plate 11 and the bottom plate 12 are connected to form an integrated T-shaped frame 1 structure through an angle weld.

[0038] The angle weld is a right-angle weld formed along the connection between the vertical plate 11 and the bottom plate 12, and can be realized by arc welding or laser welding process. A continuous joint surface is formed by continuous welding. The integrated T-shaped frame 1 structure is a whole frame formed by the vertical plate 11 and the bottom plate 12 through welding, which cannot be disassembled. The whole frame can be realized by machining after welding, eliminating the assembly gap of the traditional split structure.

[0039] Specifically, during the manufacturing process of the T-shaped frame 1, the vertical end faces of the vertical plate 11 and the bottom plate 12 are welded through an angle weld around the whole circumference, and the weld covers all edge areas of the contact surface of the vertical plate 11 and the bottom plate 12. After welding, the welding stress is eliminated through a heat treatment process, and then the flatness of the support surface of the bottom plate 12 is corrected. The whole structure formed in this way will not produce relative displacement between the vertical plate 11 and the bottom plate 12 when bearing the support force of the outer steel plate 6 and the middle steel plate 5, avoiding the measurement error of the layer spacing caused by structural deformation.

[0040] The T-shaped frame 1 adopts an integrated structure to eliminate the assembly interface, control the perpendicularity error of the support surface within the process reference range, and reduce the structural deformation caused by vibration. The integrated structure solves the problem of measurement error of the layer spacing caused by unstable connection structure of the traditional split support frame, ensures that the relative position between the inner steel plate 4 and the outer and middle steel plates 5 remains constant during transient electromagnetic signal acquisition, and improves the repeatability precision of the inner plate thickness detection. The integrated structure also reduces the maintenance demand of the support frame due to long-term use, prolonging the service life of the detection device.

[0041] With reference to Figures 1-3The application further provides a three-layer stainless steel container inner layer plate thickness transient electromagnetic testing device, and the plurality of nuts 31 are stacked and arranged on the bolt 3 to increase the contact support area with the outer layer steel plate 6 or the middle layer steel plate 5.

[0042] The two or more standard hexagonal nuts 31 are sequentially assembled along the axial direction of the bolt 3, and specifically, the nuts 31 in the M8 or M10 specification can be stacked and arranged, and a combined support structure is formed through thread engagement. The structure expands the axial contact length by increasing the number of nuts 31, thereby dispersing the pressure of the steel plate stress area. The contact support area is the effective bearing area of the nut 31 group and the steel plate contact surface, and specifically, the contact length can reach 15-20 mm by stacking 3-4 nuts 31, and the continuous support surface formed by the end surface of the plurality of nuts 31 covers the edge area of the steel plate, preventing local deformation of the steel plate during the locking process of the bolt 3.

[0043] Specifically, when the outer layer steel plate 6 and the middle layer steel plate 5 are fixed in the stand plate 11 height adjustment groove 2, the bolt 3 passes through the reserved hole in the edge of the steel plate, and then the operator selects the number of stacked nuts 31 according to the thickness of the steel plate. For example, for a steel plate with a thickness of 4 mm, two nuts 31 can be stacked to form a support section of 8 mm; for a steel plate with a thickness of 6 mm, three nuts 31 can be stacked to form a support section of 12 mm. The nut 31 group after stacking forms a surface contact with the steel plate through the end surface, which effectively reduces the stress concentration phenomenon of the steel plate edge during the locking process compared with the point contact mode of the single nut 31. At the same time, the stepped structure formed by the stacked nuts 31 can adapt to steel plates of different thicknesses, and the length of the support section can be flexibly adjusted by increasing or decreasing the number of nuts 31.

[0044] The combined support structure formed by the stacked nuts 31 uniformly distributes the locking force by expanding the contact area, which not only avoids deformation of the steel plate but also improves the fixing stability. In addition, this structure does not need to be customized with special size support parts, and only by stacking standard nuts 31 can it adapt to steel plates of different thicknesses, significantly enhancing the universality of the device and effectively solving the deformation problem caused by local stress during the fixing of multi-layer steel plates, ensuring that the outer layer steel plate 6 and the middle layer steel plate 5 remain flat during the adjustment process, providing a stable interlayer spacing reference for transient electromagnetic detection. The expanded support surface formed by the stacked nuts 31 can also adapt to the fixing needs of steel plates of different thicknesses, avoiding support failure caused by differences in steel plate thickness, and improving the adaptation ability of the device to three-layer containers of different specifications.

[0045] The application further provides that the heat preservation material can be filled between the outer layer steel plate 6 and the middle layer steel plate 5, and between the middle layer steel plate 5 and the inner layer steel plate 4.

[0046] The heat preservation material is a heat insulation material for filling the interlayer gap and reducing heat conduction, and can be specifically implemented by rock wool, aluminum silicate fiber or aerogel material. Such materials have low thermal conductivity and high temperature resistance, and can effectively block the interference of temperature on transient electromagnetic signal acquisition.

[0047] In the transient electromagnetic test process, the heat preservation material is filled into the interlayer region between the outer steel plate 6 and the middle steel plate 5 and the interlayer region between the middle steel plate 5 and the inner steel plate 4. By filling the heat preservation material, the interlayer gap is uniformly filled, avoiding the deformation or spacing change of the steel plate caused by the temperature gradient, thereby maintaining the relative position stability of the steel plates in the test process. At the same time, the heat preservation material can isolate the influence of external environmental temperature fluctuation on the test area, ensuring that the transient electromagnetic signal acquisition only reflects the change of the steel plate thickness, avoiding the introduction of additional errors caused by environmental temperature interference.

[0048] The present scheme fills the heat preservation material to block the interlayer heat transfer path at the physical level, eliminate the influence of temperature change on the spacing between the steel plates and the electromagnetic characteristics, focus the signal acquisition process only on the thickness change of the steel plate, significantly improve the stability of the test data, solve the signal distortion problem caused by interlayer temperature conduction in the process of testing the thickness of the inner layer plate of the three-layer stainless steel container, and ensure that the test device can still maintain stable interlayer spacing and electromagnetic signal acquisition conditions in a complex temperature environment, thereby improving the accuracy and repeatability of the thickness detection of the inner steel plate 4.

[0049] Referring to Figures 1-5 , the present application further provides a three-layer stainless steel container inner layer plate thickness transient electromagnetic test method, comprising the following steps: adjusting the interlayer spacing of the outer steel plate 6, the middle steel plate 5 and the inner steel plate 4 through the test device according to the design parameters of the three-layer stainless steel container; acquiring the transient electromagnetic decay curve by using the transient electromagnetic technology to collect signals from the adjusted three-layer steel plate; selecting a preset number of points as a time window interval with a preset point before the third inflection point of the decay curve as the starting point of the time window; calculating the measured value of the thickness of the inner steel plate 4 based on the signal data in the time window interval, and selecting a corresponding correction coefficient for error correction according to the measured thinning rate of the inner steel plate 4 to obtain the final value of the inner layer plate thickness.

[0050] The design parameters are the original structure parameters of the steel plates of each layer of the container, which can be obtained from engineering drawings or process documents, and are used to determine the initial spacing adjustment reference of the steel plates of each layer to ensure the effective penetration depth of the transient electromagnetic signal. The transient electromagnetic decay curve is a curve of the secondary field voltage changing with time collected by the receiving coil, which can be generated by the data acquisition module of the transient electromagnetic instrument, and is used to reflect the attenuation characteristics of the electromagnetic field by different steel plate layers. The third pre-set point before the third inflection point is a specific data point before the third obvious turning point of the decay curve, which can be identified by numerical differentiation to determine the starting position of the effective time window for signal analysis. The time window interval is a range of multiple data points selected continuously from the starting point, which can be realized by setting a fixed number of sampling points, and is used to extract the signal feature segment with significant thickness correlation. The measured thinning rate is the reduction ratio of the current thickness of the inner steel plate 4 relative to the initial reference thickness, which can be calculated by the difference between the measured thickness and the reference thickness, and is used to match the corresponding correction coefficient to eliminate the signal interference error caused by the multi-layer structure. The correction coefficient is a numerical adjustment factor set according to the thinning degree, which can be used to compensate for the electromagnetic field distortion error caused by the corrosion thinning of the steel plate.

[0051] Specifically, the test device adjusts the position of the bolt 3 in the height adjustment groove 2 according to the thickness of the outer steel plate 6, the thickness of the middle steel plate 5 and the interlayer spacing requirement in the container design parameters, so that the outer steel plate 6 and the middle steel plate 5 are fixed at the set height respectively, and the inner steel plate 4 is directly placed on the support surface of the bottom plate 12, forming a three-layer spacing structure meeting the detection requirements. The transient electromagnetic probe emits a pulsed magnetic field on the surface of the steel plate, and the receiving coil collects the secondary field signal decaying with time to form a decay curve containing the thickness information of the three-layer steel plate. By identifying the inflection points of the curve, the two points before the third inflection point are selected as the starting points of the time window, and three points are continuously selected backward to form the analysis interval. The signal amplitude data is extracted in this interval, and the initial calculated thickness is compensated for error by combining the correction coefficient, and finally the accurate thickness value of the inner steel plate 4 is obtained.

[0052] Compared with the prior art, the existing pulse eddy current technology can only detect the thickness of a single layer of steel plate and cannot penetrate the multi-layer structure to obtain the inner layer information; the conventional ultrasonic detection needs to invade the inside of the container, which has safety risks and affects the production continuity. The present method optimizes the electromagnetic field penetration path by accurately adjusting the interlayer spacing, combines the time window feature extraction and thinning rate correction algorithm, effectively eliminates the electromagnetic coupling interference between the multi-layer steel plates, and for the first time realizes the non-contact measurement of the inner layer thickness of the three-layer structure, avoiding the safety hazards and production stagnation problems of the open tank detection.

[0053] By the technical scheme, the technical problem that the inner layer plate thickness of the three-layer stainless steel container cannot be detected externally is solved, the safety risk in the detection process and the influence of production interruption are eliminated, the accuracy and reliability of the thickness detection are improved, and the inner layer corrosion monitoring of the three-layer structure equipment with strict safety requirements such as medical inactivation containers is especially suitable.

[0054] With reference to Figures 1-5 In step 3, the third inflection point is further preset to be two points before the third inflection point, and the time window interval is an interval formed by selecting three points after the starting point.

[0055] The third inflection point is a turning point where the third signal attenuation rate in the transient electromagnetic decay curve suddenly changes, and can be realized by finding the extreme point of the second derivative of the curve, and is used to locate the critical position of the signal feature change. The preset point is a discrete data point offset forward from the third inflection point, which can be obtained by using an equal interval sampling method, and is used to determine the starting position of the time window. The time window interval is an analysis range formed by continuously selecting multiple data points from the starting point, which can be set based on the sampling frequency of the data acquisition system, and is used to extract effective signals and suppress noise interference.

[0056] Specifically, in the transient electromagnetic decay curve analysis process, two points before the third inflection point are selected as the starting point of the time window, and the starting point is extended by three points to form a fixed-length analysis interval. By limiting the signal processing range within this interval, high-frequency noise in the initial stage of the decay curve and low signal-to-noise ratio regions in the later stage can be effectively excluded, thereby focusing on the middle section signal reflecting the thickness characteristics of the inner steel plate 4.

[0057] Compared with the prior art, the conventional transient electromagnetic detection method usually uses fixed time window or full section signal analysis, and it is difficult to avoid errors caused by noise interference and signal attenuation. The present scheme realizes accurate control of the signal processing range by positioning the feature inflection point and selecting a specific point interval, which significantly improves the data reliability of the inner steel plate 4 thickness inversion.

[0058] By the technical scheme, the technical problem that the inner layer plate thickness of the three-layer stainless steel container cannot be detected externally is solved, the safety risk in the detection process and the influence of production interruption are eliminated, the accuracy and reliability of the thickness detection are improved, and the inner layer corrosion monitoring of the three-layer structure equipment with strict safety requirements such as medical inactivation containers is especially suitable.

[0059] With reference to Figures 1-5The application further proposes that in step 4, the corresponding relationship between the measured thinning rate and the correction coefficient is: when the measured thinning rate is less than or equal to 5%, the correction coefficient is 1.0; when the measured thinning rate is 10% to 20%, the correction coefficient is 1.3; when the measured thinning rate is 20% to 30%, the correction coefficient is 1.6; and when the measured thinning rate is 30% to 40%, the correction coefficient is 1.9.

[0060] The measured thinning rate is the thickness reduction ratio of the inner layer steel plate 4 calculated by the transient electromagnetic decay curve, which can be calculated by the difference percentage between the measured thickness value and the reference thickness value, and is used to represent the corrosion degree of the inner layer steel plate 4. The correction coefficient is a numerical adjustment factor matched according to the measured thinning rate interval, which can be realized by piecewise linear interpolation or interval mapping, and is used to compensate for the nonlinear attenuation error of the transient electromagnetic signal under different corrosion degrees.

[0061] Specifically, after the measured value of the thickness of the inner layer steel plate 4 is calculated from the time window interval signal data, the measured thinning rate is compared with the preset interval threshold value, and the corresponding correction coefficient is dynamically selected to multiply the measured value. For example, when the measured thinning rate is in the interval of 10% to 20%, the correction coefficient of 1.3 is used to amplify the original calculation result, so as to offset the measurement deviation caused by the abnormal attenuation of the electromagnetic signal due to the accumulation of corrosion products. By establishing the segmented corresponding relationship between the thinning rate and the correction coefficient, the differential error compensation can be implemented according to the thickness change characteristics of the inner layer steel plate 4 in different corrosion stages.

[0062] Compared with the prior art, the traditional transient electromagnetic detection method does not consider the nonlinear influence of the thinning rate of the inner layer steel plate 4 in the multi-layer structure on the signal attenuation, resulting in systematic deviation of the measurement result with the deepening of the corrosion degree. The present scheme effectively solves the nonlinear correlation problem between the corrosion layer thickness change and the electromagnetic signal attenuation by introducing the dynamic matching mechanism of the thinning rate and the correction coefficient.

[0063] Through the above technical scheme, the application can automatically adapt the error correction parameter according to the actual corrosion degree of the inner layer steel plate 4, significantly improve the accuracy of the thickness detection result, and especially avoid misjudgment caused by signal distortion under high thinning rate conditions, and ensure the reliability of the inner layer plate thickness detection data of safety sensitive equipment such as medical inactivation containers.

[0064] Reference Figures 1-5 The application further proposes that in step 1, the design parameters include the thickness of the outer layer steel plate 6, the thickness of the middle layer steel plate 5, the reference thickness of the inner layer steel plate 4, the outer layer-middle layer spacing, and the middle layer-inner layer spacing.

[0065] The thickness of the outer layer steel plate 6 is the thickness of the steel plate constituting the outermost protective layer of the container, which can be measured by an ultrasonic thickness gauge to ensure the structural integrity of the outer layer steel plate 6. The thickness of the middle layer steel plate 5 is the thickness of the jacket layer, which can be obtained by presetting calibration data or offline detection, and is used to calculate the energy attenuation of the electromagnetic signal penetrating the jacket layer. The reference thickness of the inner layer steel plate 4 is the original thickness of the inner cylinder layer in the non-corrosion state, which can be determined according to the factory parameters or historical detection records of the equipment, and is used as the calculation basis for the thickness reduction rate. The outer layer-middle layer spacing is the air gap or the thickness of the filler layer between the outer protective layer and the jacket layer, and the middle layer-inner layer spacing is the gap between the jacket layer and the inner cylinder layer, which can be controlled by adjusting the position of the bolt 3 of the test device to match the propagation characteristics of the transient electromagnetic signal.

[0066] Specifically, when adjusting the test device, the initial positioning point of the bolt 3 in the height adjustment groove 2 needs to be calculated according to the thickness of the outer layer steel plate 6 and the thickness of the middle layer steel plate 5 to ensure the stability of the support of the outer layer steel plate 6 and the middle layer steel plate 5. The setting of the outer layer-middle layer spacing and the middle layer-inner layer spacing needs to be combined with the effective penetration depth of the transient electromagnetic signal. For example, when the thickness of the outer layer steel plate 6 is 4 mm, the outer layer-middle layer spacing can be adjusted to 5-8 mm to avoid signal shielding. The reference thickness of the inner layer steel plate 4 is used as the comparison basis for the measured thickness reduction rate. For example, when the reference thickness is 10 mm, if the measured value is 8 mm, the thickness reduction rate is 20%. By inputting the above design parameters into the test device, the relative positions of the steel plates can be accurately controlled to ensure that the transient electromagnetic signal can penetrate the outer layer and the middle layer and accurately reflect the thickness of the inner layer.

[0067] In some embodiments, the adjustment of the outer layer-middle layer spacing and the middle layer-inner layer spacing can be achieved by stacking multiple nuts 31, for example, two stacked nuts 31 are installed on the bolt 3 to increase the contact area. The reference thickness of the inner layer steel plate 4 can be obtained in combination with the equipment nameplate information or historical detection report, for example, the reference thickness of the inner layer of a certain medical inactivation container is recorded as 12 mm.

[0068] Compared with the prior art, the existing detection method only sets parameters for single-layer steel plate structure, for example, the pulse eddy current technology only considers the thickness of the outer layer and ignores the interaction between the jacket layer and the inner layer. The present scheme introduces the thickness of the multi-layer steel plate and the layer spacing parameters to establish a transient electromagnetic signal propagation model suitable for three-layer structure, for example, the electromagnetic interference of the outer layer and the middle layer steel plate 5 is compensated simultaneously during signal acquisition, solving the limitation that the existing technology cannot penetrate multi-layer structure.

[0069] By the technical scheme, the application can realize accurate adjustment of layer spacing based on design parameters of a multi-layer structure. For example, in medical inactivation container detection, by inputting thickness parameters of 4 mm for the outer layer and 6 mm for the middle layer, the positioning height of the bolt 3 is automatically calculated and the spacing is locked at 7 mm. The scheme effectively avoids signal distortion caused by layer spacing deviation, reduces the calculation error of the actual thickness of the inner layer steel plate 4 to within 5%, and completes the detection without opening the container, thereby ensuring the safety and continuity of the detection process.

[0070] With reference to Figures 1-5 The application further provides a three-layer stainless steel container inner plate thickness transient electromagnetic testing method. When adjusting the testing device, the inner layer steel plate 4 is directly placed on the bottom plate 12 of the T-shaped bracket 1, and the outer layer steel plate 6 and the middle layer steel plate 5 are fixed at the height adjustment groove 2 of the vertical plate 11 by cooperating with the bolt 3 and the nut 31.

[0071] The bottom plate 12 of the T-shaped bracket 1 is a support structure formed by the vertical connection of the vertical plate 11 and the bottom plate 12, which can be realized by welding or integrated forming process, and is used for directly bearing the inner layer steel plate 4 and ensuring that the inner layer steel plate 4 and the vertical plate 11 maintain a vertical positioning relationship. The bolt 3 cooperates with the nut 31 to adjust the position of the bolt 3 in the height adjustment groove 2 by a threaded connection mode, which can be realized by combining a standard hexagonal bolt 3 with a matching nut 31, and the clamping and fixing of the outer layer steel plate 6 and the middle layer steel plate 5 are realized by tightening the nut 31. The height adjustment groove 2 is a strip-shaped through hole opened along the vertical plate 11, which can be formed by laser cutting or milling processing, and the edge is provided with a scale mark 21 to assist positioning, and the height adjustment of the outer layer steel plate 6 and the middle layer steel plate 5 is realized by moving the position of the bolt 3 in the groove.

[0072] Specifically, when the testing method is implemented, the inner layer steel plate 4 is directly placed on the bottom plate 12 of the T-shaped bracket 1 and is kept stable by the horizontal bearing surface of the bottom plate 12; the outer layer steel plate 6 and the middle layer steel plate 5 pass through the height adjustment groove 2 on the vertical plate 11 through the bolt 3, and are fixed by the locking force of the nut 31 on the bolt 3. By adjusting the installation position of the bolt 3 in the height adjustment groove 2, the spacing between the outer layer steel plate 6 and the middle layer steel plate 5 and the spacing between the middle layer steel plate 5 and the inner layer steel plate 4 can be changed, and the layer distance meeting the design parameter requirements is formed. The adjustment process does not need to disassemble the container or intrude into the interior, and only needs to operate the bolt 3 and the nut 31 externally to complete the spacing configuration of the multi-layer steel plate, thereby providing accurate testing conditions for subsequent transient electromagnetic signal acquisition.

[0073] Compared with the prior art, the traditional method needs to detect the inner layer steel plate 4 through an invasive probe or disassemble the container, and there are operation risks and production interruption problems. The scheme directly supports the inner layer steel plate 4 through the bottom plate 12 of the T-shaped frame 1, and realizes the non-contact positioning of the outer layer and the middle layer steel plate 5 in combination with the adjustable bolt 3 fixing structure on the vertical plate 11, avoids the damage to the container structure, and can accurately control the spacing between the multiple layers through external adjustment, and ensures the collection accuracy of the transient electromagnetic signal.

[0074] Through the above technical scheme, the non-invasive detection of the thickness of the inner layer steel plate 4 of the three-layer stainless steel container is realized, the spacing adjustment between the outer layer and the middle layer steel plate 5 is completed through the external bolt 3 and the height adjustment groove 2, the surface of the inner layer steel plate 4 does not need to be opened or contacted, the risk of toxin leakage in the detection process is effectively avoided, the production continuity is maintained, and the scheme is especially suitable for medical inactivation containers and other scenes with strict requirements for safety and operation convenience.

[0075] The places not mentioned in the application can be realized by using or referring to the existing technology.

[0076] Each embodiment in the specification is described in a progressive manner, and the same and similar parts between each embodiment can be referred to each other, and each embodiment mainly describes the difference from other embodiments.

[0077] The above only describes the embodiments of the application and is not used to limit the application. The application can have various changes and modifications for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the application should be included in the scope of the claims of the application.

Claims

1. A transient electromagnetic testing device for the thickness of the inner layer plate of a three-layer stainless steel container, characterized in that, Includes T-shaped frame and fixing components; The T-shaped frame is composed of a vertically connected upright plate and a base plate. The upright plate is provided with at least one height adjustment groove, and the edge of the height adjustment groove is provided with scale markings. The fixing assembly includes a bolt and a nut, the bolt being movable along the height adjustment groove, and the nut cooperating with the bolt to support and fix the outer and middle steel plates of the three layers of stainless steel. The base plate is used to directly support the inner steel plate of the three layers of stainless steel, so that the inner steel plate, outer steel plate, and middle steel plate form an adjustable spacing.

2. The transient electromagnetic testing device for the thickness of the inner layer plate of a three-layer stainless steel container according to claim 1, characterized in that, The upright plate is provided with two parallel height adjustment slots, which correspond to the bolt installation positions supporting the outer steel plate and the middle steel plate, respectively.

3. The transient electromagnetic testing device for the thickness of the inner layer plate of a three-layer stainless steel container according to claim 1, characterized in that, The upright plate and the base plate are connected by fillet welds to form an integrated T-shaped frame structure.

4. The transient electromagnetic testing device for the thickness of the inner layer plate of a three-layer stainless steel container according to claim 1, characterized in that, The nuts are multiple, and the multiple nuts are stacked and sleeved on the bolt to increase the contact support area with the outer or middle steel plate.

5. The transient electromagnetic testing device for the thickness of the inner layer plate of a three-layer stainless steel container according to claim 3, characterized in that, It also includes thermal insulation material, which can be filled between the outer steel plate and the middle steel plate, and between the middle steel plate and the inner steel plate.

6. A transient electromagnetic testing method for the thickness of the inner layer plate of a three-layer stainless steel container, characterized in that, Includes the following steps: Step 1: Based on the design parameters of the three-layer stainless steel container, adjust the interlayer spacing of the outer, middle and inner steel plates using a testing device. Step 2: Use transient electromagnetic technology to acquire signals from the adjusted three-layer steel plate and obtain the transient electromagnetic attenuation curve; Step 3: Using the preset point before the third inflection point of the attenuation curve as the starting point of the time window, select a preset number of points as the time window interval; Step 4: Calculate the measured value of the inner layer steel plate thickness based on the signal data within the time window interval, and select the corresponding correction coefficient according to the measured thinning rate of the inner layer steel plate to correct the error, so as to obtain the final value of the inner layer plate thickness.

7. The transient electromagnetic testing method for the thickness of the inner layer plate of a three-layer stainless steel container according to claim 6, characterized in that, In step 3, the preset points before the third inflection point are the two points before the third inflection point, and the time window interval is the interval formed by selecting three points from the starting point.

8. The transient electromagnetic testing method for the thickness of the inner layer plate of a three-layer stainless steel container according to claim 6, characterized in that, In step 4, the correspondence between the measured thinning rate and the correction coefficient is as follows: when the measured thinning rate is ≤5%, the correction coefficient is 1.0; when the measured thinning rate is 10%~20%, the correction coefficient is 1.3; when the measured thinning rate is 20%~30%, the correction coefficient is 1.6; and when the measured thinning rate is 30%~40%, the correction coefficient is 1.

9.

9. The transient electromagnetic testing method for the thickness of the inner layer plate of a three-layer stainless steel container according to claim 6, characterized in that, In step 1, the design parameters include the outer steel plate thickness, the middle steel plate thickness, the inner steel plate reference thickness, the outer-middle layer spacing, and the middle-inner layer spacing.

10. A transient electromagnetic testing method for the thickness of the inner layer plate of a three-layer stainless steel container according to claim 6, characterized in that, In step 1, when adjusting the testing device, the inner steel plate is placed directly on the T-shaped frame base plate, and the outer and middle steel plates are fixed to the height adjustment groove of the upright plate by bolts and nuts.

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