Method for adjusting multi-specification comparison sample tubes for seamless steel tubes through eddy current inspection

Abstract

The invention discloses a through type eddy current inspection multi-specification comparison sample tube adjusting method for a seamless steel tube. The method comprises the following steps: S1, operation preparation; s2, preparing a contrast sample tube; s3, adjusting the eddy current detection equipment by using the comparison sample tube; s4, calculating an increase or decrease value of the gain; s5, performing eddy current flaw detection; and S6, recording information. According to the method, when the outer diameter of the seamless tube is not changed and only the wall thickness is changed, or the outer diameter of the seamless tube is changed and the wall thickness is not changed, the preparation consumption of the comparison sample tube is reduced by establishing the method meeting the multi-specification eddy current flaw detection operation.

Description

Technical Field

[0001] The present invention relates to a process for producing seamless steel pipes in the metallurgical and mechanical industries, and more specifically, to a method for adjusting a multi-specification comparison sample pipe for through-type eddy current flaw detection of seamless steel pipes, which is particularly suitable for eddy current flaw detection production of non-magnetic metal seamless pipes with a finished pipe diameter of φ15 to 150 mm and a wall thickness of less than 6 mm. Background Art

[0002] Eddy current flaw detection is a flaw detection method that uses the principle of electromagnetic induction to detect surface or near-surface defects of components and metal materials. The principle is to use an excitation coil to generate eddy current in a conductive component, and use a detection coil to measure the change in eddy current to obtain relevant information about component defects. Eddy current flaw detection can be divided into three types of coils: through-type, insertion-type, and probe-type according to the shape of the detection coil. That is:

[0003] 1) A through-type coil is a coil in which the sample to be tested is placed for testing. It is suitable for flaw detection of tubes, rods, and wires. Since the magnetic field generated by the coil first acts on the outer wall of the sample, it is more effective in detecting defects on the outer wall.

[0004] 2) The internal insertion coil is a coil placed inside the pipe hole for testing. It is specially used to check the defects of thick walls or the inner wall of the pipe hole, and is also used to check the quality of the pipes in the complete set of equipment. In terms of structure, the internal insertion coil is also a through-type coil, but the external through-type is that the pipe passes through the coil, while the internal insertion type is that the pipe passes through the outside of the coil.

[0005] 3) The probe coil is a coil placed on the surface of the sample for testing. It is not only suitable for surface scanning flaw detection of simple-shaped plates, slabs, square billets, round billets, bars and large-diameter pipes, but also suitable for the inspection of mechanical parts with more complex shapes. Compared with the through-type coil, the probe coil is small in size and has a small field range, so it is suitable for detecting smaller surface defects.

[0006] Due to the characteristics of eddy current testing such as accuracy, cost, and efficiency, when conducting non-destructive testing of finished and semi-finished products (work-in-progress) of seamless steel pipes and metal seamless pipes, through-type eddy current testing is the preferred method for detecting outer wall defects.

[0007] As we all know, through-type eddy current testing requires a comparison sample tube to adjust the flaw detection system. Under the same detection conditions such as frequency, filtering, speed, etc., the eddy current distribution in materials of different specifications is different, and the signal phase and amplitude formed are also different. Therefore, every time a product specification is changed, it is necessary to replace a comparison sample tube of the specification and adjust the flaw detection system. The so-called seamless steel pipe specification changes include changes in outer diameter, inner diameter, and wall thickness. This change can be a change in one size specification, or a combination of two or even three sizes. For example:

[0008] φ38*2mm changes to φ32*2mm - the outer diameter changes but the wall thickness remains unchanged;

[0009] φ32*4mm changes to φ32*2mm——the wall thickness changes (inner diameter changes), and the outer diameter remains unchanged;

[0010] φ48*5mm changes to φ25*3mm - both the outer diameter and the wall thickness (inner diameter) change.

[0011] National standards such as GB / T5777-2019 "Full Circumferential Automatic Ultrasonic Testing of Longitudinal and / or Transverse Defects in Seamless and Welded (Except Submerged Arc Welded) Steel Tubes", GB / T5248-2016 "Eddy Current Flaw Detection Method for Copper and Copper Alloy Seamless Tubes", GB / T7735-2004 "Eddy Current Flaw Detection Method for Steel Tubes", GB / T7735-87 "Eddy Current Flaw Detection Method for Steel Tubes", and GB / T12969.2-91 "Eddy Current Flaw Detection Method for Titanium and Titanium Alloy Tubes" do not make detailed definition values ​​for the changes in specifications and dimensions during eddy current testing. Therefore, in production practice, all companies use relevant national standards as the basis and implement eddy current flaw detection operations for seamless steel tubes and metal seamless tubes in accordance with contractual agreements such as specific delivery technical requirements.

[0012] At present, the industry widely adopts the method of customizing at least one comparison sample tube to perform online precision calibration of eddy current flaw detection equipment according to the specific specifications and sizes of seamless steel pipes and metal seamless pipes that need eddy current flaw detection. In other words, there are as many matching comparison sample tubes as there are specifications; at the same time, according to the product use, material, precision and other requirements, different inspection quality levels are selected and combined with them, and the number of comparison sample tubes increases geometrically. An ordinary seamless steel pipe or metal seamless pipe manufacturer often has hundreds of comparison sample tubes, which consume material costs, production costs, metering costs, etc., and the comparison sample tubes need to be updated in time, not once and for all, so the cost of comparison sample tubes for eddy current flaw detection remains high, and the daily placement, management and maintenance of hundreds of comparison sample tubes also add burden to the company.

[0013] In production practice, before eddy current flaw detection of seamless steel pipes and metal seamless pipes, a pipe that has been processed into a pipe with artificial defects (through holes) according to the detection technical requirements must be taken from the pipe to be inspected. This pipe is called a comparison sample pipe for the eddy current automatic detection system to use for online adjustment. Taking seamless steel pipes as an example, the eddy current flaw detection process of a certain specification pipe (D×S, where D is the nominal outer diameter of the seamless steel pipe and S is the nominal wall thickness of the seamless steel pipe) to be inspected includes:

[0014] 1. Processing comparison sample tube

[0015] a) According to the requirements of the inspection quality level, processing requirements and defect shape (radial through hole), a comparison sample tube with three artificial through hole defects is processed. The three artificial through holes are processed in the middle of the comparison sample tube, and the intervals between them in the length direction of the comparison sample tube are 200mm, and the cross-section circumference is distributed at 120°;

[0016] b) Measure the diameter of the processed artificial through holes and issue a measurement report;

[0017] 2. Use the comparison sample tube to adjust the eddy current testing equipment

[0018] a) First, install the through-type probe and centering sleeve matching the outer diameter of the pipe on the eddy current testing equipment according to the corresponding requirements;

[0019] b) Adjust the level of the probe rack and the rollers on both sides so that the center lines of the front roller, the probe rack with the probe installed, and the rear roller are in the same straight line to ensure smooth movement of the pipe;

[0020] c) First set the detection frequency (usually any value in the range of 10-30KHz), alarm mode (select amplitude mode), and alarm threshold (usually any value in the range of 30%-60%) on the eddy current detection instrument; then preliminarily set the phase, gain, filtering, scanning and other parameters;

[0021] d) The control sample tube is then conveyed on a roller conveyor through a pass-through probe mounted in a probe holder;

[0022] e) Observe the phases of the three artificial through holes in the middle of the comparison sample tube on the display screen of the eddy current testing instrument and make the following relevant adjustments;

[0023] ① Adjust the "Phase" parameter to rotate the artificial through-hole echo signal to coincide with the Y-axis (vertical axis)

[0024] ② Adjust the "Gain" parameter so that the amplitude of the echo signal of the artificial through hole just reaches the alarm threshold and record this value

[0025] ③ Adjust the "filter" parameters to maximize the signal-to-noise ratio of the artificial through-hole echo signal (artificial through-hole signal / material noise signal) (the ratio of the wave height should be greater than 3).

[0026] ④ Adjust the "scan" parameters so that the echo signals of all three artificial through holes on the comparison sample tube and the entire signal of any length of the tube to be inspected (generally estimate the scanning length required to fill the screen for the longest tube in the entire batch of materials to be inspected) can be displayed on one screen

[0027] g) If it is found that there are other identifiable signals on the comparison sample tube in addition to the three processed artificial through holes, the comparison sample tube should be discarded, and another tube without other identifiable signals should be selected from the tubes to be tested based on these parameters. This tube should be used to re-process a comparison sample tube according to steps a) and b) of the first paragraph, and the eddy current testing equipment should be adjusted again according to steps a) to e) of the second paragraph;

[0028] 3. Eddy current flaw detection

[0029] a) Use the comparison sample tube to adjust the eddy current testing system and then start testing the tubes to be tested one by one;

[0030] b) According to regulations, the eddy current testing system shall be calibrated again with the comparison sample tube after a certain interval until all the tubes are inspected.

[0031] As for the above-mentioned eddy current flaw detection process, its characteristics are:

[0032] ① One-to-one correspondence, each specification needs to be processed according to the technical requirements to make a comparison sample tube for calibrating the eddy current detection system;

[0033] ② When the above-mentioned g) situation occurs (when the comparison sample tube is found to have other discernible signals during adjustment), it is necessary to make another comparison sample tube without other discernible signals.

[0034] ③ Over the years, a metal seamless pipe manufacturer spends countless amounts of money on sample material, processing, and measurement, especially the recently developed high-alloy element pipes, which are of high value and consume more. In addition, the site area used to place the sample pipes is large, which is not conducive to on-site 6S management.

[0035] In summary, in the eddy current flaw detection of seamless steel pipes and metal seamless pipes, comparison sample pipes are essential, and each specification needs to be prepared in advance for the purpose of online precision calibration of eddy current flaw detection. Therefore, for enterprises, in order to meet the needs of eddy current flaw detection of various specifications, the number of comparison sample pipes prepared is large, the cost is high, the land is large, and the calibration operation is time-consuming. At the same time, each replacement of the comparison sample pipe and calibration operation requires high skills and experience of the operators. Summary of the invention

[0036] In view of the above-mentioned defects existing in the prior art, the purpose of the present invention is to provide a method for calibrating multi-specification comparison sample pipes for through-type eddy current flaw detection of seamless steel pipes, comprehensively considering that the outer diameter of the seamless pipe remains unchanged but only the wall thickness changes, or the outer diameter of the seamless pipe changes but the wall thickness remains unchanged, by establishing a method that meets the multi-specification eddy current flaw detection operation, the preparation consumption of the comparison sample pipes can be reduced.

[0037] To achieve the above object, the present invention adopts the following technical solution:

[0038] A method for calibrating a multi-specification comparison sample pipe for through-type eddy current flaw detection of a seamless steel pipe comprises the following steps:

[0039] S1. Operation preparation;

[0040] S2, preparing a comparison sample tube;

[0041] S3. Use the comparison sample tube to calibrate the eddy current testing equipment;

[0042] S4, calculating the increase or decrease value of the gain;

[0043] S5, eddy current flaw detection;

[0044] S6. Record information.

[0045] Preferably, the operation preparation in step S1 specifically includes:

[0046] Maintenance of eddy current flaw detection equipment, verification of technical parameters of seamless steel pipes to be inspected, verification of quantity and specifications, briefing of key points of safety and quality operation for operators, and clarification of inspection quality level.

[0047] Preferably, the step S2 of preparing the comparison sample tube comprises the following steps:

[0048] S21. Process a comparison sample tube with three artificial through-hole defects according to the inspection quality level requirements, processing requirements, and defect shape requirements. The three artificial through-holes are processed in the middle of the comparison sample tube, with a spacing of 200 mm in the length direction of the comparison sample tube and a distribution of 120° on the cross-section circumference;

[0049] S22. Measure the diameters of the three artificial through holes and issue a measurement report.

[0050] Preferably, the step S3 of calibrating the eddy current testing equipment using a comparison sample tube comprises the following steps:

[0051] S31. First, install a through-type probe and a centering sleeve matching the outer diameter of the pipe on the eddy current testing equipment according to corresponding requirements;

[0052] S32. Adjust the level of the probe rack and the rollers on both sides so that the center lines of the front roller, the probe rack with the probe installed, and the rear roller are on the same straight line to ensure smooth movement of the pipe;

[0053] S33, first set the detection frequency, alarm mode, and alarm threshold on the eddy current detection equipment, and then preliminarily set the phase, gain, filtering, and scanning parameters;

[0054] S34, then the comparison sample tube is transported on a roller conveyor through a through-type probe installed in a probe rack;

[0055] S35, observing the phases of the three artificial through holes in the middle of the comparison sample tube on the display screen of the eddy current testing device, and adjusting them;

[0056] S36. If it is found that there are other identifiable signals on the comparison sample tube in addition to the three processed artificial through holes, the comparison sample tube should be discarded, and these parameters should be used to select another tube without other identifiable signals from the tubes to be tested. This tube is then used to re-process a comparison sample tube according to steps S21 and S22, and the eddy current testing equipment is adjusted again according to steps S31 to S35.

[0057] Preferably, the step S35 of adjusting on the display screen of the eddy current testing device specifically includes:

[0058] a. Adjust the phase parameters to rotate the echo signal of the artificial through hole to coincide with the Y axis;

[0059] b. Adjust the gain parameter so that the echo signal of the artificial through hole reaches the alarm threshold and record the value;

[0060] c. Adjust the filtering parameters to maximize the signal-to-noise ratio of the echo signal of the artificial through hole;

[0061] d. Adjust the scanning parameters so that the echo signals of the three artificial through holes and the entire signal of any length of the pipe to be inspected are displayed on one display screen.

[0062] Preferably, the step S4 of calculating the increase or decrease value of the gain specifically includes:

[0063] Δ12=10lg(t2 / t1)

[0064] In the formula, Δ12 represents the sensitivity change after the wall thickness changes, in dB; t1 represents the wall thickness of the current comparison sample pipe, in mm; t2 represents the wall thickness of the pipe to be tested, in mm.

[0065] Preferably, the step S5 eddy current flaw detection comprises the following steps:

[0066] S51, use the comparison sample tube to test the eddy current test equipment and start testing the tubes to be tested one by one;

[0067] S52. After the prescribed interval, use the comparison sample tube to inspect the eddy current testing equipment again until all the tubes are inspected.

[0068] The present invention provides a method for calibrating a multi-specification comparison sample pipe for through-type eddy current flaw detection of a seamless steel pipe, which has the following beneficial effects:

[0069] 1) The process design is reasonable, which is an on-site deepening and improvement of the existing national standards and industry standards, and the on-site practical application has achieved remarkable results;

[0070] 2) The process is compact, the engineering calculation model is reasonable, the sensitivity change value after the wall thickness changes is calculated accurately, and the operation is fast. It is the first technology in the domestic industry. There is no similar technology abroad, which has a certain degree of creativity;

[0071] 3) When the pipe wall changes from thick (the wall thickness of the current comparison sample pipe) to thin (the wall thickness of the pipe to be tested), the calculated sensitivity change value is "negative", and the required sensitivity value is attenuated based on the sensitivity value of the current comparison sample pipe;

[0072] 4) When the pipe wall changes from thin (the wall thickness of the current comparison sample) to thick (the wall thickness of the pipe to be tested), the calculated sensitivity change value is "positive", then the required sensitivity value is increased based on the sensitivity value of the current comparison sample;

[0073] 5) Sample tube preparation and equipment adjustment are convenient, saving labor and time, and the parameter settings are reasonable, safe, reliable, practical and efficient;

[0074] 6) With big data and computing models as support, the requirements for operator skills and experience are reduced, facilitating human resource allocation;

[0075] 7) Effectively reduce the number of comparison sample tubes prepared, and achieve a comparison sample tube that meets the technical requirements of eddy current flaw detection under similar conditions, with high cost performance and continuous significant cost reduction effect;

[0076] 8) It has strong versatility and has certain reference and application value for improving the eddy current flaw detection process of metal seamless steel in the industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 It is a schematic flow chart of a method for calibrating a through-type eddy current flaw detection multi-specification comparison sample tube according to the present invention;

[0078] Figure 2 Schematic diagram of step S35 in the calibration method of through-type eddy current flaw detection multi-specification comparison sample tube of the present invention Figure 1 ;

[0079] Figure 3 Schematic diagram of step S35 in the calibration method of through-type eddy current flaw detection multi-specification comparison sample tube of the present invention Figure 2 . DETAILED DESCRIPTION

[0080] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0081] Combination Figure 1 As shown, the present invention provides a method for calibrating a multi-specification comparison sample pipe for through-type eddy current flaw detection of a seamless steel pipe, comprising the following steps:

[0082] S1. Preparation:

[0083] Maintenance of eddy current flaw detection equipment, verification of technical parameters of seamless steel pipes to be inspected, verification of quantity and specifications, briefing of key operating points such as safety and quality for operators, clarification of inspection quality levels, etc.

[0084] S2. Prepare a comparison sample tube, specifically comprising the following steps:

[0085] S21. Process a comparison sample tube with three artificial through-hole defects according to the inspection quality level requirements, processing requirements, and defect shape (radial through-hole) requirements. The three artificial through-holes are processed in the middle of the comparison sample tube, and are spaced 200 mm apart in the length direction of the comparison sample tube, and the cross-sectional circumference is distributed at 120°;

[0086] S22. Measure the diameters of the three artificial through holes and issue a measurement report.

[0087] S3. Calibrate the eddy current testing equipment using a comparison sample tube, specifically including the following steps:

[0088] S31. First, install a through-type probe and a centering sleeve matching the outer diameter of the pipe on the eddy current testing equipment according to corresponding requirements;

[0089] S32. Adjust the level of the probe rack and the rollers on both sides so that the center lines of the front roller, the probe rack with the probe installed, and the rear roller are on the same straight line to ensure smooth movement of the pipe;

[0090] S33, first set the detection frequency (generally any value in the range of 10-30KHz), alarm mode (select amplitude mode), alarm threshold (generally any value in the range of 30-60%) on the eddy current detection equipment, and then preliminarily set the phase, gain, filtering, scanning and other parameters;

[0091] S34, then the comparison sample tube is transported on a roller conveyor through a through-type probe installed in a probe rack;

[0092] S35, observing the phases of the three artificial through holes in the middle of the comparison sample tube on the display screen of the eddy current testing device, and adjusting them;

[0093] S36. If it is found that there are other identifiable signals on the comparison sample tube in addition to the three processed artificial through holes, the comparison sample tube should be discarded, and these parameters should be used to select another tube without other identifiable signals from the tubes to be tested. This tube is then used to re-process a comparison sample tube according to steps S21 and S22, and the eddy current testing equipment is adjusted again according to steps S31 to S35.

[0094] Combination Figure 2and Figure 3 As shown, step S35 of adjusting on the display screen of the eddy current testing device specifically includes:

[0095] a. Adjust the phase parameter to rotate the echo signal of the artificial through hole to coincide with the Y axis (vertical axis);

[0096] b. Adjust the gain parameter so that the echo signal of the artificial through hole reaches the alarm threshold and record the value;

[0097] c. Adjust the filtering parameters to maximize the signal-to-noise ratio of the echo signal of the artificial through hole (artificial through hole signal / material noise signal) (the ratio of the wave height should be greater than 3);

[0098] d. Adjust the scanning parameters so that the echo signals of the three artificial through holes and the entire signal of any length of the pipe to be inspected (generally, the scanning length required to fill the screen for the longest pipe in the entire batch of materials to be inspected is estimated) are all displayed on one display screen.

[0099] S4. Calculate the increase or decrease value of gain:

[0100] Δ12=10lg(t2 / t1)

[0101] In the formula, Δ12 represents the sensitivity change after the wall thickness changes, in dB; t1 represents the wall thickness of the current comparison sample pipe, in mm; t2 represents the wall thickness of the pipe to be tested, in mm.

[0102] a) When the pipe wall changes from thick (the wall thickness of the current comparison sample pipe) to thin (the wall thickness of the pipe to be tested), the calculated sensitivity change value is "negative", and the required sensitivity value is attenuated based on the sensitivity value of the current comparison sample pipe;

[0103] b) When the pipe wall changes from thin (the wall thickness of the current comparison sample) to thick (the wall thickness of the pipe to be tested), the calculated sensitivity change value is "positive", and the required sensitivity value is the gain based on the sensitivity value of the current comparison sample.

[0104] S5. Eddy current flaw detection, specifically including the following steps:

[0105] S51, use the comparison sample tube to test the eddy current test equipment and start testing the tubes to be tested one by one;

[0106] S52. After the prescribed interval, use the comparison sample tube to inspect the eddy current testing equipment again until all the tubes are inspected.

[0107] S6. Record information:

[0108] Record the actual information of eddy current flaw detection of this batch of seamless steel pipes.

[0109] According to the above process (process step) model, the eddy current flaw detection automated non-destructive testing of non-magnetic seamless steel pipes and metal seamless pipes can be completed on the eddy current flaw detection equipment.

[0110] The present invention is aimed at the technical improvement and practice of the current eddy current flaw detection process of seamless steel pipes and metal seamless steel. It effectively reduces the number of comparison sample tubes prepared, and realizes a comparison sample tube that meets the technical requirements of eddy current flaw detection of specifications under similar conditions. It has high cost performance and continuous and significant cost reduction effect, achieving a cost reduction of more than 1 million yuan per year. The process design is reasonable, which is an on-site deepening and improvement of the existing national standards and industry standards. When the pipe wall changes from thick (the wall thickness of the current comparison sample pipe) to thin (the wall thickness of the pipe to be tested), the calculated sensitivity change value is "negative", and the required sensitivity value is attenuated on the basis of the sensitivity value of the current comparison sample pipe; when the pipe wall changes from thin (the wall thickness of the current comparison sample pipe) to thick (the wall thickness of the pipe to be tested), the calculated sensitivity change value is "positive", and the required sensitivity value is increased on the basis of the sensitivity value of the current comparison sample; the process connection is compact, the engineering calculation model is reasonable, the calculation is fast, the sensitivity change value after the wall thickness changes is calculated accurately, the sample pipe preparation and equipment adjustment are convenient, labor and time are saved, the parameter setting is reasonable, safe and reliable, practical and efficient, and on the basis of meeting the technical requirements of eddy current flaw detection of seamless steel pipes and metal seamless pipes, the number of preparation and replacement of comparison sample pipes in eddy current flaw detection operations is effectively reduced, which is the first technology in China (industry). With big data and computing models as support, it reduces the requirements for operating personnel's skills and experience, and facilitates human resource allocation; it has strong versatility and has certain reference and application value for improving the eddy current flaw detection process methods of metal seamless steel in the industry.

[0111] Example 1

[0112] The metal seamless pipe to be inspected is made of 0Cr18Ni10Ti, with a nominal specification of φ57*4mm and is required to be tested according to the E3H quality level in GB / T5777-2016. The process method of eddy current flaw detection automatic non-destructive testing includes the following steps:

[0113] S1. Preparation:

[0114] Maintenance of eddy current flaw detection equipment, verification of technical parameters of seamless steel pipes to be inspected, verification of quantity and specification φ57*4mm, briefing of key points of operation such as safety and quality for operators, and clarification of inspection quality level such as E3H.

[0115] S2. Prepare a comparison sample tube, specifically comprising the following steps:

[0116] S21. Take an existing comparison sample tube with an outer diameter of 57 mm, the same material, the same manufacturing process, the same delivery status, the same surface condition, the same inspection quality level and a wall thickness of 2.5 mm.

[0117] a1) Check the diameter of the artificial through hole on the comparison sample tube: Figure 1 It was found that the diameter of the E3H-grade artificial through hole of this φ57*2.5mm comparison sample tube is 1.60mm.

[0118] a2) Check the number of artificial through holes on the comparison sample tube: This φ57*2.5mm comparison sample tube has 3 1.60mm artificial through holes in the middle (which meets the test requirements).

[0119] a3) Check the positions of the artificial through holes on the comparison sample tube: The three artificial through holes in the middle of the comparison sample tube are distributed at intervals of 120° on the circumference of the cross section and 200 mm apart in the length direction.

[0120] S22. Measure the diameters of the three artificial through holes and issue a measurement report.

[0121] S3. Use the 57*2.5mm comparison sample tube for calibration of the through-type eddy current automatic detection system:

[0122] b1) First install the through-type probe and centering sleeve matching the outer diameter of the pipe on the equipment according to the corresponding requirements;

[0123] b2) Adjust the level of the probe rack and the rollers on both sides so that the center lines of the front roller, the probe rack with the probe installed, and the rear roller are in the same straight line to ensure smooth movement of the pipe;

[0124] b3) On the eddy current testing instrument, first set the testing frequency to 15KHz, the alarm mode to amplitude, and the alarm threshold to 50%; then preliminarily set the phase, gain, filtering, scanning and other parameters to certain values;

[0125] b4) Then the φ57*2.5mm comparison sample tube is transported on a roller conveyor through a through-type probe installed in a probe rack;

[0126] b5) Observe the phase of the three artificial through holes in the middle of the φ57*2.5mm comparison sample tube on the display screen of the eddy current testing instrument;

[0127] Combination Figure 2 and Figure 3 As shown, the adjustment on the display screen of the eddy current testing equipment specifically includes:

[0128] ①Adjust the "Phase" parameter to make Figure 3 The 1.60mm artificial through-hole echo signal of any phase angle is rotated to coincide with the Y axis (vertical axis);

[0129] ② Adjust the "Gain" parameter so that the amplitude of the echo signal of the 1.60mm artificial through hole on the Y axis just reaches the 50% alarm threshold, and record this value (assuming Figure 2 The sensitivity of the instrument is 38dB in this state.

[0130] ③Adjust the "Filter" parameter to make Figure 3 The signal-to-noise ratio of 1.84 (70 / 38 = 1.84) is increased to Figure 2 The signal-to-noise ratio of 20 (50 / 25 = 20)

[0131] b6) Observe the display screen of the eddy current testing instrument

[0132] Adjust the "scan" parameters so that the echo signals of all three artificial through holes on the comparison sample tube and the entire signal of any length of the tube to be inspected (generally, it is estimated that the scanning length required to fill the screen for the longest tube in the entire batch of materials to be inspected) can be displayed on one screen.

[0133] S4. Calculate the increase or decrease value of gain:

[0134] 1. Δ12 = 10lg (t2 / t1)

[0135] In the formula, Δ12 represents the sensitivity change after the wall thickness changes, in dB; t1 represents the wall thickness of the current comparison sample pipe, in mm; t2 represents the wall thickness of the pipe to be tested, in mm.

[0136] △12=10lg(4.0 / 2.5)=2.04dB≈2dB (the minimum adjustment step on general eddy current testing instruments is 0.5dB / step).

[0137] 2. Calculate the detection sensitivity value of the E3H level for the target specification of 57*4mm

[0138] ① The sensitivity value of the replacement comparison sample tube 57*2.5mm specification and E3H level is 38dB

[0139] ②The calculated change value △12 is 2dB

[0140] ③Then the detection sensitivity value of 57*4mm target specification and E3H level should be 38+2=40dB.

[0141] S5. Eddy current flaw detection, specifically including the following steps:

[0142] a) On the eddy current testing instrument, adjust the scale of 38 (dB) up by 2 digits to 40 (dB), and keep other parameters unchanged.

[0143] b) Use the comparison sample tube to adjust the eddy current testing system and then start testing the tubes to be tested one by one;

[0144] c) According to regulations, the eddy current testing system shall be calibrated again with the comparison sample tube after a certain interval until all the tubes are inspected.

[0145] S6. Record information:

[0146] Record the actual information of eddy current flaw detection of this batch of seamless steel pipes.

[0147] Example 2

[0148] The material of the metal seamless pipe to be inspected is UNSN06690, the nominal specification is φ25*2mm, and the through-type eddy current test is required to be carried out in accordance with the E3H quality level in GB / T5777-2016. The process method of the eddy current flaw detection automatic non-destructive testing includes the following steps:

[0149] S1. Preparation:

[0150] Maintenance of eddy current flaw detection equipment, verification of technical parameters of seamless steel pipes to be inspected, verification of quantity and specification φ25*2mm, briefing of key points of operation such as safety and quality for operators, and clarification of inspection quality level such as E3H.

[0151] S2. Prepare a comparison sample tube, specifically comprising the following steps:

[0152] S21. Take an existing comparison sample tube with the same outer diameter of φ25mm, the same material, the same manufacturing process, the same delivery status, the same surface condition, the same inspection quality level but with a wall thickness of 4.0mm.

[0153] a1) Check the diameter of the artificial through hole required on the comparison sample tube: press Figure 1 It was found that the diameter of the E3H grade artificial through hole of this φ25*2mm comparison sample tube was 1.30mm.

[0154] a2) Check the number of artificial through holes on the existing φ25*4mm comparison sample tube: the comparison sample tube has 3 1.30mm artificial through holes in the middle (which meets the test requirements).

[0155] a3) Check the positions of the artificial through holes on the existing φ25*4mm comparison sample tube: the three artificial through holes in the middle of the comparison sample tube are distributed at 120° intervals on the circumference of the cross section and 200mm apart in the length direction.

[0156] S22. Measure the diameters of the three artificial through holes and issue a measurement report.

[0157] S3. Use the φ25*4mm comparison sample tube for calibration of the through-type eddy current automatic detection system:

[0158] b1) First install the through-type probe and centering sleeve matching the outer diameter of the pipe on the equipment according to the corresponding requirements;

[0159] b2) Adjust the level of the probe rack and the rollers on both sides so that the center lines of the front roller, the probe rack with the probe installed, and the rear roller are in the same straight line to ensure smooth movement of the pipe;

[0160] b3) On the eddy current testing instrument, first set the testing frequency to 15KHz, the alarm mode to amplitude, and the alarm threshold to 50%; then preliminarily set the phase, gain, filtering, scanning and other parameters to certain values;

[0161] b4) Then the φ25*4mm comparison sample tube is transported on a roller conveyor through a through-type probe installed in the probe rack;

[0162] b5) Observe the phase of the three artificial through holes in the middle of the φ25*4mm comparison sample tube on the display screen of the eddy current testing instrument;

[0163] Combination Figure 2 and Figure 3 As shown, the adjustment on the display screen of the eddy current testing equipment specifically includes:

[0164] ①Adjust the "Phase" parameter to make Figure 3 The 1.30mm artificial through-hole echo signal of any phase angle is rotated to coincide with the Y axis (vertical axis) ( Figure 2 ).

[0165] ② Adjust the "Gain" parameter so that the amplitude of the echo signal of the 1.30mm artificial through hole on the Y axis just reaches the 50% alarm threshold, and record this value (assuming Figure 2 The sensitivity of the instrument is 35dB in this state.

[0166] ③Adjust the "Filter" parameter to make Figure 3 The signal-to-noise ratio value of 1.85 (72 / 39 = 1.85) is increased to Figure 2 The signal-to-noise ratio of 25 (50 / 2=25)

[0167] b6) Observe the display screen of the eddy current testing instrument

[0168] Adjust the "scan" parameters so that the echo signals of all three artificial through holes on the comparison sample tube and the entire signal of any length of the tube to be inspected (generally, it is estimated that the scanning length required to fill the screen for the longest tube in the entire batch of materials to be inspected) can be displayed on one screen.

[0169] S4. Calculate the increase or decrease value of gain:

[0170] 1. Δ12 = 10lg (t2 / t1)

[0171] In the formula, Δ12 represents the sensitivity change after the wall thickness changes, in dB; t1 represents the wall thickness of the current comparison sample pipe, in mm; t2 represents the wall thickness of the pipe to be tested, in mm.

[0172] △12=10lg(2.0 / 4.0)=-3.01dB≈-3dB (the minimum adjustment step on general eddy current testing instruments is 0.5dB / step).

[0173] 2. Calculate the detection sensitivity value of the E3H level for the target specification of 25*2mm

[0174] ① The sensitivity value of the replacement comparison sample tube 25*4mm specification and E3H level is 35dB

[0175] ②The calculated change value △12 is -3dB

[0176] ③Then the detection sensitivity value of 25*2mm target specification and E3H level should be 35+(-3)=35-3=32dB.

[0177] S5. Eddy current flaw detection, specifically including the following steps:

[0178] a) On the eddy current testing instrument, adjust the scale from 35 (dB) down by 3 digits to 32 (dB), and keep other parameters unchanged.

[0179] b) Use the comparison sample tube to adjust the eddy current testing system and then start testing the tubes to be tested one by one;

[0180] c) According to regulations, the eddy current testing system shall be calibrated again with the comparison sample tube after a certain interval until all the tubes are inspected.

[0181] S6. Record information:

[0182] Record the actual information of eddy current flaw detection of this batch of seamless steel pipes.

[0183] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A method for calibrating a multi-specification comparison sample tube for through-type eddy current flaw detection of seamless steel tubes, characterized in that: The following steps are involved: S1. Operation preparation; S2, preparing a comparison sample tube; S3. Use the comparison sample tube to calibrate the eddy current testing equipment; S4, calculating the increase or decrease value of the gain; S5, eddy current flaw detection; S6. Record information.

2. The method for calibrating a multi-specification comparison sample pipe for through-type eddy current flaw detection of a seamless steel pipe according to claim 1, characterized in that: The step S1 operation preparation specifically includes: Maintenance of eddy current flaw detection equipment, verification of technical parameters of seamless steel pipes to be inspected, verification of quantity and specifications, briefing of key points of safety and quality operation for operators, and clarification of inspection quality level.

3. The method for calibrating a multi-specification comparison sample pipe for through-type eddy current flaw detection of a seamless steel pipe according to claim 1, characterized in that: The step S2 of preparing the comparison sample tube comprises the following steps: S21. Process a comparison sample tube with three artificial through-hole defects according to the inspection quality level requirements, processing requirements, and defect shape requirements. The three artificial through-holes are processed in the middle of the comparison sample tube, and are spaced 200 mm apart in the length direction of the comparison sample tube, and the cross-sectional circumference is distributed at 120°; S22. Measure the diameters of the three artificial through holes and issue a measurement report.

4. The method for calibrating a multi-specification comparison sample pipe for through-type eddy current flaw detection of a seamless steel pipe according to claim 3, characterized in that: The step S3 of calibrating the eddy current testing equipment using the comparison sample tube comprises the following steps: S31. First, install a through-type probe and a centering sleeve matching the outer diameter of the pipe on the eddy current testing equipment according to corresponding requirements; S32. Adjust the level of the probe rack and the rollers on both sides so that the center lines of the front roller, the probe rack with the probe installed, and the rear roller are on the same straight line to ensure smooth movement of the pipe; S33, first set the detection frequency, alarm mode, and alarm threshold on the eddy current detection equipment, and then preliminarily set the phase, gain, filtering, and scanning parameters; S34, then the comparison sample tube is transported on a roller conveyor through a through-type probe installed in a probe rack; S35, observing the phases of the three artificial through holes in the middle of the comparison sample tube on the display screen of the eddy current testing device, and adjusting them; S36. If it is found that the comparison sample tube has other identifiable signals besides the three processed artificial through holes, the comparison sample tube should be discarded, and these parameters should be used to select another tube without other identifiable signals from the tubes to be tested. This tube should be used to re-process a comparison sample tube according to steps S21 and S22, and the eddy current testing equipment should be adjusted again according to steps S31 to S35.

5. The method for calibrating a multi-specification comparison sample pipe for through-type eddy current flaw detection of a seamless steel pipe according to claim 4, characterized in that: The step S35 of adjusting on the display screen of the eddy current testing device specifically includes: a. Adjust the phase parameters to rotate the echo signal of the artificial through hole to coincide with the Y axis; b. Adjust the gain parameter so that the echo signal of the artificial through hole reaches the alarm threshold and record the value; c. Adjust the filtering parameters to maximize the signal-to-noise ratio of the echo signal of the artificial through hole; d. Adjust the scanning parameters so that the echo signals of the three artificial through holes and the entire signal of any length of the pipe to be inspected are displayed on one display screen.

6. The method for calibrating a multi-specification comparison sample pipe for through-type eddy current flaw detection of a seamless steel pipe according to claim 1, characterized in that: The step S4 of calculating the increase or decrease value of the gain specifically includes: Δ12=10lg(t2 / t1) In the formula, Δ12 represents the sensitivity change after the wall thickness changes, in dB; t1 represents the wall thickness of the current comparison sample pipe, in mm; t2 represents the wall thickness of the pipe to be tested, in mm.

7. The method for calibrating a multi-specification comparison sample pipe for through-type eddy current flaw detection of a seamless steel pipe according to claim 5, characterized in that: Step S5 eddy current flaw detection The following steps are involved: S51, use the comparison sample tube to test the eddy current test equipment and start testing the tubes to be tested one by one; S52. After the prescribed interval, use the comparison sample tube to inspect the eddy current testing equipment again until all the tubes are inspected.

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