Longitudinal groove tube eddy current testing method and apparatus
By using eddy current testing methods and equipment for longitudinal grooved tubes, the problem of inaccurate testing results for longitudinal grooved tubes has been solved, enabling accurate detection of defects in longitudinal grooved tubes and improving the yield rate, thereby reducing manufacturing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING GROUNDSUN TECH CO LTD
- Filing Date
- 2023-12-25
- Publication Date
- 2026-07-21
AI Technical Summary
The existing inspection process for longitudinal grooved pipes has the problem of inaccurate evaluation of inspection results, which prevents the inspection process from proceeding normally.
The longitudinal groove pipe eddy current testing method is adopted, which includes steps such as eddy current testing of non-ferromagnetic metal pipes, judgment of relevant and irrelevant display signals, detection of abrupt changes in shape and cracks, analysis of damage depth map, PT testing and penetrant retesting. Multiple tests are performed in combination with the detection coil, eddy current meter and filter of the eddy current testing equipment to ensure accuracy and efficiency.
It enables precise detection of defects in longitudinal grooved pipes, improves the accuracy and efficiency of detection results, reduces manufacturing costs, increases yield, and improves the pass rate of longitudinal grooved pipes through repair methods.
Smart Images
Figure CN117761150B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of eddy current testing technology, and in particular to a method and equipment for eddy current testing of longitudinal grooved pipes. Background Technology
[0002] Currently, large-scale chemical enterprises in China, including petrochemical and coal chemical low-carbon olefin separation processes, widely use high-throughput longitudinal groove tubes. Longitudinal groove tubes have good heat transfer performance in boiling heat transfer and condensation heat transfer. The boiling heat transfer coefficient of the porous surface is more than ten times that of the plain tube, and the condensation heat transfer of the longitudinal groove is three to four times that of the plain tube.
[0003] However, the existing inspection process for longitudinally grooved tubes has significant flaws. When using conventional non-destructive testing methods to inspect longitudinally grooved tubes, the inspection process cannot proceed normally because the test results cannot be accurately evaluated.
[0004] Therefore, there is an urgent need for a testing method specifically designed for longitudinally grooved pipes to ensure the smooth progress of the entire testing process and achieve good detection results. Summary of the Invention
[0005] The purpose of this invention is to provide a method and equipment for eddy current testing of longitudinal grooved pipes, which uses eddy current to achieve good detection results for the longitudinal grooved pipes under test.
[0006] To achieve this objective, the present invention adopts the following technical solution:
[0007] The eddy current testing method for longitudinally grooved tubes, used to test longitudinally grooved tubes, includes the following steps:
[0008] S10: Perform eddy current testing on the longitudinal grooved pipe under test for non-ferromagnetic metal pipes, and obtain the corresponding relevant and unrelated display signals;
[0009] S20: Determine whether there is an unrelevant display signal with an undetermined deficiency. If yes, proceed to S30; otherwise, proceed to S40.
[0010] S30: Based on the cause of the non-correlated display signal, determine the corresponding deficiency according to the detection standard, and then return to S20;
[0011] S40: Determine whether there is a shape change display signal among the unrelated display signals. If yes, proceed to S50. If no, output the information that there is no shape change and then proceed to S60.
[0012] S50: Determine if there is a crack at the abrupt change in shape. If yes, output the information that there is a crack and then proceed to S60. If no, output the information that there is no crack and then proceed to S60.
[0013] S60: Analyze the relevant display signals, determine the depth of the scratch according to the corresponding scratch depth map, and determine whether the depth exceeds the predetermined depth. If so, process it as a scrapped product; otherwise, process it as a repairable product, and then proceed to S70.
[0014] S70: Perform PT testing on the relevant display area of the repairable product to determine the nature and location of the defect, and then repair it. After the repair is completed, perform penetrant testing and eddy current testing.
[0015] S80: Determine whether the repair is qualified based on the results of the penetrant retest and eddy current retest. If it is, proceed to S90; otherwise, treat it as a scrapped product.
[0016] S90: Determine whether the longitudinal groove tube to be tested has completed the eddy current test of the in-use non-ferromagnetic heat exchange tube. If yes, generate a test record and report, and output the longitudinal groove tube to be tested as a qualified product. If no, perform eddy current test on the longitudinal groove tube to be tested as an in-use non-ferromagnetic heat exchange tube, obtain the corresponding relevant display signals and unrelated display signals, and return to S20.
[0017] As a preferred technical solution for eddy current testing of longitudinal grooved tubes, when performing eddy current testing on non-ferromagnetic metal tubes and / or on in-use non-ferromagnetic heat exchange tubes, a method for adjusting the testing frequency is included. This method comprises the following steps: preheating the longitudinal grooved tube eddy current testing equipment for a predetermined time; switching the equipment to a near-surface, single-frequency application mode; turning off the filter of the equipment; resetting the phase angle obtained from the test to zero; deriving the minimum testing frequency for the test sample tube, and setting half of the testing frequency... Set the frequency to the initial detection frequency; slowly and smoothly pass the test sample tube through the detection coil of the longitudinal groove tube eddy current testing equipment, and simultaneously observe the eddy current meter display of the longitudinal groove tube eddy current testing equipment to determine whether a through-hole defect is displayed; if no through-hole defect is displayed, increase the frequency by the minimum amount and repeat the previous step until the through-hole defect is found; after the through-hole defect is found, continue to increase the frequency by the minimum amount until the phase angle of the through-hole defect is close to horizontal; remove the test sample tube and set the current detection frequency as the optimal detection frequency.
[0018] As a preferred technical solution for the eddy current detection method of longitudinal grooved tubes, the predetermined time is 10 minutes.
[0019] As a preferred technical solution for the eddy current testing method for longitudinal grooved tubes, when performing eddy current testing on non-ferromagnetic metal tubes and / or on in-use non-ferromagnetic heat exchange tubes, a filter debugging method is included. This filter debugging method comprises the following steps: preheating the longitudinal grooved tube eddy current testing equipment for a predetermined time; switching the longitudinal grooved tube eddy current testing equipment to a near-surface, single-frequency application mode; turning off the filter; resetting the phase angle obtained from the test to zero; determining the optimal test frequency according to the test frequency debugging method; and simultaneously and slowly and smoothly passing the test sample tube through the test coil. Check the eddy current meter display to determine if the through-hole defect is easily identifiable and has minimal noise. If the through-hole defect is difficult to identify and has high noise, modulate the filter by setting the high-pass filter to an initial frequency of 2Hz and increasing the low-pass filter from 10Hz in increments of 5Hz until the through-hole defect is easily identifiable. If this does not achieve minimal noise, increase the high-pass filter from 2Hz in increments of 1Hz until the through-hole defect is easily identifiable and has minimal noise. Remove the test sample tube; the filter adjustment is now complete.
[0020] As a preferred technical solution for the eddy current detection method of longitudinal grooved tubes, the predetermined time is 10 minutes.
[0021] As a preferred technical solution for the eddy current testing method for longitudinal grooved tubes, when performing eddy current testing on non-ferromagnetic metal pipes and / or on in-use non-ferromagnetic heat exchange tubes, a phase angle adjustment method is included. This phase angle adjustment method comprises the following steps: adjusting the longitudinal grooved tube eddy current testing equipment using the detection frequency adjustment method and the filter adjustment method; setting the phase angle displayed by the through-hole defect to a predetermined angle; sequentially passing through natural defects of other depths, selecting the most acceptable defect depth as the standard depth; if the phase angle of the most acceptable defect is the predetermined angle, no further adjustments are needed; if the phase angle of the most acceptable defect is not the predetermined angle, the phase angle is readjusted according to the standard hole parameters until the phase angle of the most acceptable defect is the predetermined angle.
[0022] As a preferred technical solution for the eddy current testing method for longitudinal grooved tubes, when performing eddy current testing on non-ferromagnetic metal pipes and / or on in-use non-ferromagnetic heat exchange tubes, a method for manually creating a damage depth map is included. This method comprises the following steps: adjusting the longitudinal grooved tube eddy current testing equipment using the testing frequency adjustment method and the filter adjustment method; setting the phase angle of the through-hole defect display to the predetermined angle; sequentially passing through natural defects of other depths and recording the corresponding phase angles; dividing the phase angle display range according to the depth direction of the artificial defects; and drawing the damage depth map of the test sample tube.
[0023] As a preferred technical solution for the eddy current detection method of longitudinal groove tube, the predetermined angle is 40°.
[0024] As a preferred technical solution for the eddy current detection method of longitudinal groove tube, the predetermined depth is 1 mm.
[0025] The longitudinal grooved tube eddy current testing equipment is applied to the aforementioned longitudinal grooved tube eddy current testing method. The longitudinal grooved tube eddy current testing equipment includes a testing coil, an eddy current meter, and a filter.
[0026] The beneficial effects of this invention are:
[0027] This eddy current testing method for longitudinally grooved tubes obtains results from two separate tests: one on non-ferromagnetic metal tubing and the other on in-use non-ferromagnetic heat exchange tubes. The test results are categorized into relevant, irrelevant, and spurious signals. Spurious signals do not need to be recorded or evaluated. Irrelevant signals are judged according to testing standards to identify all defects. These steps help confirm the causes of defects, preventing them from interfering with the test results and thus improving the efficiency and accuracy of the eddy current testing. By determining the presence of abrupt shape changes and further examining for cracks at these changes, precise inspection of the longitudinally grooved tube's appearance is achieved, helping to pinpoint the location of manufacturing defects. Using the corresponding scratch depth diagram, the depth of the scratches is determined, and the possibility of repair is assessed. This achieves the goal of scratch depth evaluation, allowing for timely removal of defective products and improving the yield rate of the longitudinally grooved tubes through repair, effectively reducing manufacturing costs. The PT (Potential Transmission) test on repairable longitudinal grooved tubes can determine the nature and location of defects. Combined with post-repair penetrant and eddy current (EDC) retesting, the repair effectiveness is assessed, further distinguishing between qualified and unqualified longitudinal grooved tubes. The eddy current testing method for longitudinal grooved tubes utilizes eddy current testing technology, establishing internal and external penetration testing processes. This facilitates analysis of the characteristics of eddy current display signals from external penetration testing, achieving good detection results. Furthermore, it allows for the conclusion that external penetration is superior to internal penetration, summarizing typical display signals for external eddy current penetration in longitudinal grooved tubes. By employing these steps, defects generated during the manufacturing process of the longitudinal grooved tubes can be detected, thus completing the eddy current testing operation and optimizing the testing scheme.
[0028] This longitudinal grooved tube eddy current testing equipment, by setting up a detection coil, eddy current meter, and filter, can meet the testing requirements of the longitudinal grooved tube eddy current testing method, ensure the smooth completion of the eddy current testing operation of the longitudinal grooved tube under test, reduce the workload of operators, and help to further improve the efficiency of eddy current testing. Attached Figure Description
[0029] Figure 1 This is a flowchart of the eddy current detection method for longitudinal grooved tubes provided in this embodiment of the invention. Detailed Implementation
[0030] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0031] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions. Furthermore, "above," "on top of," and "over" the first feature in relation to the second feature includes the first feature directly above and diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "under," and "below" the first feature in relation to the second feature includes the first feature directly below and diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0032] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0033] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0034] like Figure 1 As shown, this embodiment provides a method for eddy current testing of longitudinally grooved tubes, used to test longitudinally grooved tubes. The method includes the following steps:
[0035] Step 1: Perform eddy current testing on the longitudinal grooved tube to be tested as a non-ferromagnetic metal tube, and obtain the relevant and irrelevant display signals.
[0036] Step 2: Determine if there are any unrelevant display signals with undetermined defects. If yes, proceed to Step 3; otherwise, proceed to Step 4.
[0037] Step 3: Based on the cause of the non-relevant display signal, determine the corresponding deficiency according to the detection standard, and then return to Step 2.
[0038] Step 4: Determine whether there is a change in shape display signal among the unrelated display signals. If yes, proceed to Step 5. If no, output the message that there is no change in shape and then proceed to Step 6.
[0039] Step 5: Determine if there is a crack at the abrupt change in shape. If yes, output the information that there is a crack and then proceed to Step 6. If no, output the information that there is no crack and then proceed to Step 6.
[0040] Step Six: Analyze the relevant display signals, determine the depth of the scratch according to the corresponding scratch depth map, and determine whether the depth exceeds the predetermined depth. If so, process it as a scrapped product; otherwise, process it as a repairable product, and then proceed to Step Seven.
[0041] Step 7: Perform PT testing on the relevant display area of the repairable product to determine the nature and location of the defect, and then carry out the repair. After the repair is completed, perform penetrant testing and eddy current testing.
[0042] Step 8: Determine whether the repair is qualified based on the results of the penetration retest and eddy current retest. If yes, proceed to step 9; otherwise, treat it as a scrapped product.
[0043] Step Nine: Determine whether the longitudinal grooved tube under test has completed the eddy current test for in-use non-ferromagnetic heat exchange tubes. If yes, generate a test record and report, and output the longitudinal grooved tube under test as a qualified product. If not, perform eddy current testing on the longitudinal grooved tube under test for in-use non-ferromagnetic heat exchange tubes, obtain the corresponding relevant and irrelevant display signals, and return to Step Two. Specifically, the predetermined depth is 1mm.
[0044] This eddy current testing method for longitudinally grooved tubes obtains results from two separate tests: one on non-ferromagnetic metal tubing and the other on in-use non-ferromagnetic heat exchange tubes. The test results are categorized into relevant, irrelevant, and spurious signals. Spurious signals do not need to be recorded or evaluated. Irrelevant signals are judged according to testing standards to identify all defects. These steps help confirm the causes of defects, preventing them from interfering with the test results and thus improving the efficiency and accuracy of the eddy current testing. By determining the presence of abrupt shape changes and further examining for cracks at these changes, precise inspection of the longitudinally grooved tube's appearance is achieved, helping to pinpoint the location of manufacturing defects. Using the corresponding scratch depth diagram, the depth of the scratches is determined, and the possibility of repair is assessed. This achieves the goal of scratch depth evaluation, allowing for timely removal of defective products and improving the yield rate of the longitudinally grooved tubes through repair, effectively reducing manufacturing costs. The PT (Potential Transmission) test on repairable longitudinal grooved tubes can determine the nature and location of defects. Combined with post-repair penetrant and eddy current (EDC) retesting, the repair effectiveness is assessed, further distinguishing between qualified and unqualified longitudinal grooved tubes. The eddy current testing method for longitudinal grooved tubes utilizes eddy current testing technology, establishing internal and external penetration testing processes. This facilitates analysis of the characteristics of eddy current display signals from external penetration testing, achieving good detection results. Furthermore, it allows for the conclusion that external penetration is superior to internal penetration, summarizing typical display signals for external eddy current penetration in longitudinal grooved tubes. By employing these steps, defects generated during the manufacturing process of the longitudinal grooved tubes can be detected, thus completing the eddy current testing operation and optimizing the testing scheme.
[0045] GB / T12604.6 and NB / T47013.1 define the following terms and definitions as applicable to this embodiment: Relevant display signals refer to the signals generated by the detector during the inspection of the longitudinal grooved tube (also called defect signals); irrelevant display signals refer to signals formed by internal or external structures unrelated to defects; spurious display signals refer to signals caused by other metallic impurities adhering to the inner or outer surfaces of the longitudinal grooved tube. Evaluation refers to the process of analyzing the observed detection-related signals to determine the causes and classification of these signals.
[0046] In this embodiment, relevant display signals include crack display and fold display; irrelevant display signals include abrupt shape change display, misaligned tooth display, scratch display, indentation display and coating defect display, etc.; spurious display signals include lift-off effect display, tube conductivity non-uniformity display, tube magnetic permeability non-uniformity display and tube noise display.
[0047] The following documents are essential for the application of this embodiment: Standard Logarithmic Visual Acuity Chart [GB11533], Eddy Current Testing Method for Seamless Tubes of Copper and Copper Alloys [GB / T5248], Eddy Current Testing Equipment for Nondestructive Testing - Part 3: System Performance and Inspection [GB / T14480.3], Method for Measuring Artificial Defect Dimensions of Steel Pipe Comparative Specimens [YB / T145], and Nondestructive Testing of Pressure Equipment - Part 1: General Requirements [NB / T47013.1]. For dated references, only the dated version applies to this embodiment. For undated references, the latest version (including any amendments) applies to this embodiment.
[0048] In this embodiment, the longitudinal groove tube to be tested is a copper-nickel longitudinal groove tube. In other embodiments of this embodiment, the longitudinal groove tube to be tested is a carbon steel longitudinal groove tube.
[0049] In this embodiment, when performing eddy current testing on non-ferromagnetic metal pipes and / or on in-use non-ferromagnetic heat exchange tubes for the longitudinal grooved tube under test, a method for adjusting the detection frequency is included. The method for adjusting the detection frequency includes the following steps: preheating the longitudinal grooved tube eddy current testing equipment for a predetermined time; switching the longitudinal grooved tube eddy current testing equipment to near-surface, single-frequency application mode; turning off the filter of the longitudinal grooved tube eddy current testing equipment; returning the phase angle obtained from the test to zero; deducing the minimum detection frequency of the test sample tube and setting 1 / 2 of the detection frequency as the initial detection frequency; slowly and smoothly passing the test sample tube through the detection coil of the longitudinal grooved tube eddy current testing equipment, while simultaneously observing the eddy current meter display of the longitudinal grooved tube eddy current testing equipment to determine whether a through-hole defect is displayed; if no through-hole defect is displayed, increasing the frequency by the minimum increment and repeating the previous step until a through-hole defect is found; after a through-hole defect is found, continuing to increase the frequency by the minimum increment until the phase angle of the through-hole defect is close to horizontal; removing the test sample tube and setting the current detection frequency as the optimal detection frequency.
[0050] The frequency adjustment method allows for optimal frequency tuning during eddy current testing. The test equipment selection involves choosing a test sample tube that meets relevant technical specifications and standards, determined in consultation with the client. These steps are simple, reliable, highly stable, and provide excellent tuning results, facilitating the rapid determination of the optimal frequency to ensure the smooth progress of the longitudinal groove tube eddy current testing method.
[0051] When turning off the filter of the detection device, the specific operation method is to switch the high-pass filter to the off mode and switch the low-pass filter to the wideband mode.
[0052] For example, when performing eddy current testing on non-ferromagnetic metal pipes and / or on in-use non-ferromagnetic heat exchanger tubes in a longitudinally grooved tube under test, a filter debugging method is included. This method comprises the following steps: preheating the longitudinally grooved tube eddy current testing equipment for a predetermined time; switching the equipment to near-surface, single-frequency application mode; turning off the filter; resetting the measured phase angle to zero; determining the optimal testing frequency according to the frequency debugging method; slowly and smoothly passing the test sample tube through the testing coil while simultaneously observing the eddy current meter display to determine if the through-hole defect display is easily identifiable and has minimal noise; if the through-hole defect display is difficult to identify and has high noise, modulate the filter by setting the high-pass filter to an initial frequency of 2Hz, and increasing the low-pass filter from 10Hz in increments of 5Hz until the through-hole defect display is easily identifiable; if this does not achieve minimal noise, increase the high-pass filter from 2Hz in increments of 1Hz until the through-hole defect display is easily identifiable and has minimal noise; remove the test sample tube; the filter debugging is complete. Specifically, the predetermined time is 10 minutes.
[0053] The filter adjustment process cannot be completed before the noise is minimized, as noise can severely affect the identification and display of via defects.
[0054] The filter debugging method allows for filter debugging during eddy current testing. The test equipment selection involves choosing test sample tubes that meet relevant technical specifications and standards agreed upon with the client. These steps are simple, reliable, highly stable, and provide good debugging results, facilitating rapid filter debugging to ensure the smooth progress of the longitudinal groove tube eddy current testing method.
[0055] The indication of defects in through holes can be determined based on the curve displayed by the eddy current analyzer. When the curve displayed by the eddy current analyzer is smooth, the defects in through holes are easy to identify and have low noise.
[0056] In this embodiment, the difficulty of identifying through-hole defects and the determination of noise level are both determined by the aforementioned documents. The concept and judgment method of easy identification and minimal noise of through-hole defects are conventional content disclosed in the aforementioned documents. The specific judgment basis is common knowledge in the field and is well mastered by those skilled in the art, and will not be elaborated here.
[0057] In this embodiment, when performing eddy current testing on non-ferromagnetic metal pipes and / or on in-use non-ferromagnetic heat exchange tubes in the longitudinal grooved tube under test, a phase angle adjustment method is included. The phase angle adjustment method includes the following steps: adjusting the longitudinal grooved tube eddy current testing equipment using a detection frequency adjustment method and a filter adjustment method; setting the phase angle of the through-hole defect display to a predetermined angle; sequentially passing through natural defects of other depths, selecting the most acceptable defect depth as the standard depth; if the phase angle of the most acceptable defect is the predetermined angle, no further adjustment is required; if the phase angle of the most acceptable defect is not the predetermined angle, the phase angle is readjusted according to the standard hole parameters until the phase angle of the most acceptable defect is the predetermined angle.
[0058] The phase angle adjustment method can be applied when calibrating eddy current testing instruments. The test equipment should be a sample tube identical to the longitudinally grooved tube being tested. The depth of the artificial defect should be determined according to relevant technical specifications and standards, or in consultation with the owner. The sample tube should have an artificially machined defect; the depth of this defect should be verified using measuring tools, and a standard hole should be identified. These steps are simple, reliable, highly stable, and provide good adjustment results, facilitating rapid phase angle adjustment to ensure the smooth progress of the longitudinally grooved tube eddy current testing method.
[0059] In this embodiment, the concept and judgment method of the phase angle of the most acceptable defect are the conventional content disclosed in the above-mentioned documents. The specific judgment basis is common knowledge in the field and is well mastered by those skilled in the art. It will not be elaborated here.
[0060] For example, when performing eddy current testing on non-ferromagnetic metal pipes and / or on in-use non-ferromagnetic heat exchanger tubes in a longitudinally grooved tube under test, a method for manually creating a flaw depth map is included. This method comprises the following steps: adjusting the longitudinally grooved tube eddy current testing equipment using methods for adjusting the testing frequency and the filter; setting the phase angle of the through-hole defect display to a predetermined angle; sequentially passing through natural defects of other depths and recording the corresponding phase angles; dividing the display range of the phase angle according to the depth direction of the artificial defect; and drawing a flaw depth map of the test sample tube. Specifically, the predetermined angle is 40°.
[0061] Among them, when the through-hole defect is easily identifiable and the noise is minimal, it is determined that the debugging method of the detection frequency and the debugging method of the filter of the longitudinal groove tube eddy current detection equipment have been completed.
[0062] The manual method for creating damage depth maps is used to provide damage depth maps during eddy current testing and evaluation. The test equipment selected is the same test sample tube as the longitudinal groove tube to be tested. The depth of the artificial defect is determined according to relevant technical specifications and standards or in consultation with the owner. The test sample tube must have artificially processed defects, and the depth of these defects is verified using measuring tools.
[0063] This embodiment also provides a longitudinal groove tube eddy current testing device, which is applied to the above-mentioned longitudinal groove tube eddy current testing method. The longitudinal groove tube eddy current testing device includes a detection coil, an eddy current meter, and a filter.
[0064] This longitudinal grooved tube eddy current testing equipment, by setting up a detection coil, eddy current meter, and filter, can meet the testing requirements of the longitudinal grooved tube eddy current testing method, ensure the smooth completion of the eddy current testing operation of the longitudinal grooved tube under test, reduce the workload of operators, and help to further improve the efficiency of eddy current testing.
[0065] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.
Claims
1. A longitudinal grooved tube eddy current testing method, used to test a longitudinal grooved tube under test, characterized in that, Includes the following steps: S10: Perform eddy current testing on the longitudinal grooved pipe under test for non-ferromagnetic metal pipes, and obtain the corresponding relevant and unrelated display signals; S20: Determine whether there is an unrelevant display signal with an undetermined deficiency. If yes, proceed to S30; otherwise, proceed to S40. S30: Based on the cause of the non-correlated display signal, determine the corresponding deficiency according to the detection standard, and then return to S20; S40: Determine whether there is a shape change display signal among the unrelated display signals. If yes, proceed to S50. If no, output the information that there is no shape change and then proceed to S60. S50: Determine if there is a crack at the abrupt change in shape. If yes, output the information that there is a crack and then proceed to S60. If no, output the information that there is no crack and then proceed to S60. S60: Analyze the relevant display signals, determine the depth of the scratch according to the corresponding scratch depth map, and determine whether the depth exceeds the predetermined depth. If so, process it as a scrapped product; otherwise, process it as a repairable product, and then proceed to S70. S70: Perform PT testing on the relevant display area of the repairable product to determine the nature and location of the defect, and then repair it. After the repair is completed, perform penetrant testing and eddy current testing. S80: Determine whether the repair is qualified based on the results of the penetrant retest and eddy current retest. If it is, proceed to S90; otherwise, treat it as a scrapped product. S90: Determine whether the longitudinal groove tube to be tested has completed the eddy current test of the in-use non-ferromagnetic heat exchange tube. If yes, generate a test record and report, and output the longitudinal groove tube to be tested as a qualified product. If no, perform eddy current test on the longitudinal groove tube to be tested as an in-use non-ferromagnetic heat exchange tube, obtain the corresponding relevant display signals and unrelated display signals, and return to S20. When performing eddy current testing on the longitudinal grooved tube under test for non-ferromagnetic metal tubes and / or on in-use non-ferromagnetic heat exchange tubes, a method for adjusting the testing frequency is included, which includes the following steps: The longitudinal groove tube eddy current testing equipment is preheated for a predetermined time; the equipment is switched to near-surface, single-frequency application mode; the filter of the equipment is turned off; the phase angle obtained from the test is zeroed; the minimum detection frequency of the test sample tube is deduced, and half of the detection frequency is set as the initial detection frequency; the test sample tube is slowly and smoothly passed through the detection coil of the longitudinal groove tube eddy current testing equipment, while simultaneously observing the eddy current meter display to determine if a through-hole defect is detected; if no through-hole defect is detected, the frequency is increased by the minimum increment, and the previous step is repeated until the through-hole defect is detected; after the through-hole defect is detected, the frequency is increased by the minimum increment until the phase angle of the through-hole defect is close to horizontal; the test sample tube is removed, and the current detection frequency is taken as the optimal detection frequency.
2. The eddy current detection method for longitudinal grooved tubes according to claim 1, characterized in that, The scheduled time is 10 minutes.
3. The eddy current detection method for longitudinal grooved tubes according to claim 1, characterized in that, When performing eddy current testing on the longitudinal grooved tube under test for non-ferromagnetic metal tubes and / or on in-use non-ferromagnetic heat exchange tubes, a filter adjustment method is included, which comprises the following steps: The longitudinal groove tube eddy current testing equipment is powered on and preheated for the predetermined time; the equipment is switched to near-surface, single-frequency application mode; the filter is turned off; the phase angle obtained from the test is returned to zero; the optimal test frequency is determined according to the frequency adjustment method; the test sample tube is slowly and smoothly passed through the test coil, and the eddy current meter display is checked simultaneously to determine whether the through-hole defect display is easy to identify and has minimal noise; if the through-hole defect display is difficult to identify and has high noise, the filter is modulated, setting the high-pass filter to an initial frequency of 2Hz, and increasing the low-pass filter from 10Hz in increments of 5Hz until the through-hole defect display is easy to identify; if this does not achieve minimal noise, the high-pass filter is increased from 2Hz in increments of 1Hz until the through-hole defect display is easy to identify and has minimal noise; the test sample tube is removed, and the filter adjustment is complete.
4. The eddy current detection method for longitudinal grooved tubes according to claim 3, characterized in that, The scheduled time is 10 minutes.
5. The eddy current detection method for longitudinal grooved tubes according to claim 3, characterized in that, When performing eddy current testing on the longitudinal grooved tube under test for non-ferromagnetic metal tubes and / or on in-use non-ferromagnetic heat exchange tubes, a method for adjusting the phase angle is included, which includes the following steps: The longitudinal groove tube eddy current testing equipment is debugged using the debugging method of the detection frequency and the debugging method of the filter; the phase angle of the through hole defect is set to a predetermined angle; natural defects of other depths are passed through in sequence, and the depth of the most acceptable defect is selected as the standard depth; if the phase angle of the most acceptable defect is the predetermined angle, no further debugging is required; if the phase angle of the most acceptable defect is not the predetermined angle, the phase angle is readjusted according to the standard hole parameters until the phase angle of the most acceptable defect is the predetermined angle.
6. The eddy current detection method for longitudinal grooved tubes according to claim 5, characterized in that, When performing eddy current testing on the longitudinal grooved tube under test for non-ferromagnetic metal tubes and / or on in-use non-ferromagnetic heat exchange tubes, a method for manually creating a damage depth map is included, which comprises the following steps: The longitudinal groove tube eddy current testing equipment is debugged using the debugging method of the detection frequency and the debugging method of the filter; the phase angle of the through hole defect display is set to the predetermined angle; natural defects of other depths are passed through in sequence, and the corresponding phase angles are recorded; the display range of the phase angle is divided according to the depth direction of the artificial defect; and the damage depth map of the test sample tube is drawn.
7. The eddy current detection method for longitudinal grooved tubes according to claim 5 or 6, characterized in that, The predetermined angle is 40°.
8. The eddy current detection method for longitudinal grooved tubes according to claim 1, characterized in that, The predetermined depth is 1 mm.
9. A longitudinal grooved tube eddy current testing device, applied to the longitudinal grooved tube eddy current testing method according to any one of claims 1-8, characterized in that, The longitudinal groove tube eddy current testing equipment includes a testing coil, an eddy current meter, and a filter.