Nondestructive testing method for detecting defects on inner surface of pipeline
By using a secondary wave-climbing detection probe and a variety of detection methods in the detection of inner surface defects of pipelines, the problem of difficulty in detecting inner surface defects of pipelines in the prior art is solved, and accurate quantification detection of defects such as corrosion and fatigue cracks is achieved.
Patent Information
- Application Number
- CN202311789689.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-22
- Publication Date
- 2025-06-24
AI Technical Summary
The prior art is difficult to effectively detect inner surface defects of pipelines, especially corrosion and fatigue cracks, and conventional ultrasonic detection is difficult to detect these defects.
The non-destructive detection method based on the secondary wave climb detection probe is adopted, including designing and testing calibration test blocks and applying tip diffraction, dual-mode and large-angle longitudinal wave detection methods, and quantitatively evaluating the inner surface defects of the pipeline through signal waveform analysis and defect position analysis.
Effective detection of defects in the inner surface of the pipeline is achieved, and defects such as corrosion and fatigue cracks can be accurately evaluated, providing important guarantees for the safety and reliability of the pipeline.
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Figure CN120195268A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of pipeline defect analysis, for example, it relates to a non-destructive testing method for detecting inner surface defects of pipelines. Background Art
[0002] Non-destructive testing is also called non-destructive inspection. Non-destructive testing is a comprehensive application technology that measures and evaluates the physical and mechanical properties inside or on the surface of substances without damaging or destroying the raw materials and workpieces and other objects to be inspected, and includes various defects and other technical parameters. It plays a key role in controlling and improving the production process and product quality, ensuring the reliability of materials, parts and products, and improving productivity. It is one of the important technical measures essential for the development of modern industry. Modern non-destructive testing and evaluation technologies not only need to detect the presence or absence of defects, but also give a quantitative evaluation of the material quality, including quantitative measurement of defects, such as the shape, size, position, orientation, distribution and inclusions of defects, as well as the quality evaluation of defective materials and products, and also include measuring certain physical and mechanical properties of materials and products. It can be said that the development level of non-destructive testing and evaluation technologies marks the modern industrial level of a country (region).
[0003] Non-destructive testing is generally divided into five conventional tests, namely ultrasonic testing, radiographic testing, magnetic particle testing, penetrant testing and eddy current testing. Ultrasonic testing has the advantages of high sensitivity, good directivity, strong penetration ability, fast detection speed, etc. It can detect both surface defects and internal defects of materials or components. Especially for planar defects such as cracks, laminations and delaminations, it has a strong detection ability. Radiographic testing method is suitable for detecting internal defects of materials or components. It is more sensitive to volume-type defects and insensitive to planar two-dimensional defects. Only when the incident direction of the ray is consistent with the crack plane, it is possible to detect crack defects. Magnetic particle testing is used to detect surface and near-surface defects of ferromagnetic materials. The equipment used for testing is simple to operate, and observing defects is intuitive and fast, with high detection sensitivity. It is especially sensitive to cracks. Liquid penetrant testing can only check surface-opening defects of materials or components. For near-surface and internal defects, the penetrant method cannot detect them. Eddy current method is only applicable to conductors and can only detect surface and near-surface defects. When performing eddy current flaw detection, the probe does not need to be in contact with the workpiece, and no coupling medium is required, so automated detection can be achieved.
[0004] Since the media used in petrochemical pipelines are mostly corrosive, high-temperature, toxic, etc., pipelines are prone to corrosion (such as intergranular or transgranular stress) and fatigue cracks during use, and their harmfulness is relatively large. These defects are generally mostly surface-opening defects on the inner surface, and it is difficult to detect them using conventional ultrasonic testing.
[0005] Based on the above problems, there is currently no effective detection method. SUMMARY OF THE INVENTION
[0006] To provide a basic understanding of some aspects of the disclosed embodiments, a simple summary is given below. This summary is not a general review, nor is it intended to identify key / important elements or delineate the scope of protection of these embodiments. Instead, it serves as a preamble to the detailed description that follows.
[0007] On the one hand, embodiments of the present disclosure provide a non-destructive testing method for detecting defects on the inner surface of a pipeline, including:
[0008] Detecting defects on the inner surface of the pipeline using a detection method based on a secondary creeping wave detection probe;
[0009] Designing a detection calibration block;
[0010] Comparing the detected inner surface defects with the detection calibration block, analyzing the defect positions, and obtaining the signal wavebands;
[0011] Evaluating the defects on the inner surface of the pipeline based on the signal waveforms.
[0012] Further, the detection method includes three types, namely the tip diffraction method, the dual-mode method, and the large-angle longitudinal wave method.
[0013] Further, the depths of the inner grooves in the calibration block include 4 types, namely 5%, 30%, 60%, and 95% of the wall thickness.
[0014] Further, the defect position analysis to obtain the signal waveforms includes:
[0015] Signal waveforms of suspected shallow defects, suspected intermediate-layer defects, and suspected deep defects.
[0016] Further, the comparison of the detected defects with the detection calibration block and the analysis of the obtained waveforms include: secondary creeping wave waveforms, secondary creeping wave and angle reflection wave waveforms, secondary creeping wave and angle reflection wave waveforms, secondary creeping wave and shear wave waveform conversion wave waveforms; secondary creeping wave, shear wave waveform conversion wave, and large-angle longitudinal wave waveforms.
[0017] Further, the tip diffraction method determines the defect depth based on the signal arrival time at the defect tip and is used to determine the size of shallow defects with a depth of 5 - 35% of the wall thickness passing through the inner groove; among them, the specifications of the detection calibration block used are: the depths of the inner grooves are 5% and 30% of the wall thickness;
[0018] The secondary creeping wave detection probe is a highly damped 5 MHz, 45° or 60° shear wave probe, and a radio frequency display is provided in the probe.
[0019] Further, the dual-mode method is used to determine the size of defects with a depth of 30 - 70% of the wall thickness passing through the inner groove.
[0020] Furthermore, the large-angle longitudinal wave method indicates the thickness of the remaining good material in the pipeline based on the signal arrival time at the defect tip, and is used to determine the defect size with a depth of 60-95% of the wall thickness passing through the inner groove.
[0021] The non-destructive testing method for detecting inner surface defects of pipelines provided by the embodiments of the present disclosure can achieve the following technical effects: By detecting inner surface defects of pipelines (such as corrosion fatigue cracks, etc.), mainly from the design of detection probes, the design of detection calibration blocks and artificial defects, the application of the terminal diffraction detection method, the dual-mode detection method, and the large-angle longitudinal wave detection method, the corrosion / fatigue cracks on the inner surface of the pipeline can be effectively detected, providing important support for the quantitative technology of pipeline corrosion / fatigue cracks.
[0022] The above general description and the following description are only exemplary and explanatory, and are not used to limit this application. Description of the Drawings
[0023] One or more embodiments are exemplarily illustrated by corresponding drawings. These exemplary illustrations and the drawings do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are shown as similar elements. The drawings do not constitute a scale limitation, and among them:
[0024] Figure 1 is the schematic diagram of the creeping wave principle provided by the embodiments of the present disclosure;
[0025] Figure 2 is the schematic diagram of the first and second creeping wave detection principles provided by the embodiments of the present disclosure;
[0026] Figure 3 is the schematic diagram of the angular reflection array wave detection principle provided by the embodiments of the present disclosure;
[0027] Figure 4 is the structural diagram of the detection probe design provided by the embodiments of the present disclosure;
[0028] Figure 5 is the front view of the calibration block provided by the embodiments of the present disclosure;
[0029] Figure 6 is the sectional view along A-A of the calibration block provided by the embodiments of the present disclosure;
[0030] Figure 7 is the waveform diagram of the terminal diffraction method provided by the embodiments of the present disclosure;
[0031] Figure 8 is the waveform diagram of the terminal diffraction signal and the angular reflection signal provided by the embodiments of the present disclosure;
[0032] Figure 9 is the radio frequency waveform diagram of the terminal diffraction signal and the angular reflection signal provided by the embodiments of the present disclosure;
[0033] Figure 10 are the tip diffraction method and the shear wave converted wave waveform diagram provided by the embodiments of the present disclosure;
[0034] Figure 11 are the tip diffraction method, the shear wave converted wave and the large angle longitudinal wave waveform diagram provided by the embodiments of the present disclosure;
[0035] Figure 12 is a flowchart of a non-destructive testing method for detecting internal surface defects of a pipeline provided by the embodiments of the present disclosure. Detailed implementation manners
[0036] In order to be able to understand the features and technical content of the embodiments of the present disclosure in more detail, the implementation of the embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are only for reference and explanation, and are not used to limit the embodiments of the present disclosure. In the following technical description, for the sake of explanation, numerous details are provided to provide a thorough understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be shown in a simplified manner to simplify the drawings.
[0037] The terms "first", "second", etc. in the specification and claims of the embodiments of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so as to implement the embodiments of the present disclosure described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion.
[0038] In the embodiments of the present disclosure, the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "middle", "outer", "front", "rear", etc. is based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the embodiments of the present disclosure and their embodiments, and are not used to limit that the indicated devices, elements or components must have a specific orientation, or be constructed and operated in a specific orientation. And, in addition to being able to represent an orientation or positional relationship, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in the embodiments of the present disclosure can be understood according to specific circumstances.
[0039] In addition, the terms "arranged", "connected", and "fixed" should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or there can be internal communication between two devices, components, or parts. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to specific circumstances.
[0040] Unless otherwise specified, the term "plurality" means two or more.
[0041] In the embodiments of the present disclosure, the character " / " indicates that the objects before and after are in an "or" relationship. For example, A / B means: A or B.
[0042] The term "and / or" is an associative relationship describing objects, indicating that there can be three relationships. For example, A and / or B means: A or B, or, the three relationships of A and B.
[0043] It should be noted that, without conflict, the embodiments in the embodiments of the present disclosure and the features in the embodiments can be combined with each other.
[0044] Combined body Figures 1-12 As shown, the embodiments of the present disclosure provide Figure 12 A non-destructive testing method for detecting defects on the inner surface of a pipeline provided by the embodiments of the present disclosure includes:
[0045] Detecting defects on the inner surface of the pipeline using a detection method based on a secondary creeping wave detection probe;
[0046] Designing a detection calibration test block;
[0047] Comparing the detected inner surface defects with the detection calibration test block, analyzing the defect positions, and obtaining signal waveforms;
[0048] Evaluating the defects on the inner surface of the pipeline based on the signal waveforms.
[0049] The design principle of the secondary creeping wave detection probe is as follows: When a longitudinal wave is incident on the second medium at an angle (within ±30°) near the first critical angle from the first medium, not only surface waves but also obliquely incident shear waves exist in the second medium. Generally, the wavefront of the obliquely incident shear wave is called the head wave, and the peak wave propagating between the obliquely incident shear wave and the surface longitudinal wave at a certain distance below the medium surface is called the longitudinal head wave or creeping wave, also known as the primary creeping wave. In order to detect the height of defects on the inner surface of the pipeline, the primary creeping wave is only on the upper surface. Therefore, it is necessary to generate a longitudinal wave under the inner surface, that is, to generate a longitudinal wave under the inner surface using an obliquely incident shear wave (about 30°) through waveform conversion, that is, the secondary creeping wave (as shown in Figure 2 Figure 10#).
[0050] In some embodiments of the present invention, the detection methods include three types, namely the tip diffraction method, the dual-mode method, and the large-angle longitudinal wave method.
[0051] In some embodiments of the present invention, the depths of the inner grooves in the calibration test block include 4 types, namely 5%, 30%, 60%, and 95% of the wall thickness.
[0052] In some embodiments of the present invention, the defect location analysis to obtain the signal waveform includes:
[0053] Suspicious shallow defect signal waveform, suspicious intermediate layer defect, and suspicious deep layer defect.
[0054] In some embodiments of the present invention, the detected defects are compared with the detection calibration test block, and the waveforms analyzed include: secondary creeping wave waveform, secondary creeping wave and angle reflection wave waveform, secondary creeping wave and angle reflection wave waveform, secondary creeping wave and shear wave waveform conversion wave waveform; secondary creeping wave, shear wave waveform conversion wave and large-angle longitudinal wave waveform.
[0055] In some embodiments of the present invention, the tip diffraction method determines the defect depth based on the signal arrival time at the defect tip, and is used to determine the size of shallow defects with a depth of 5-35% of the wall thickness passing through the inner groove; among them, the specifications of the detection calibration test block used are: two types with the depth of the inner groove being 5% and 30% of the wall thickness;
[0056] The secondary creeping wave detection probe is a highly damped 5 MHz, 45° or 60° shear wave probe, and a radio frequency display is provided in the probe.
[0057] In some embodiments of the present invention, the dual-mode method is used to determine the size of defects with a depth of 30-70% of the wall thickness passing through the inner groove.
[0058] In some embodiments of the present invention, the large-angle longitudinal wave method indicates the thickness of the remaining good material in the pipeline based on the signal arrival time at the defect tip, and is used to determine the size of defects with a depth of 60-95% of the wall thickness passing through the inner groove.
[0059] Figure 1 It includes: wafer 1, probe 2, creeping wave 3, main longitudinal wave 4, longitudinal wave envelope 5, shear wave 6, head wave 7.
[0060] Figure 2 It includes shear wave 6, longitudinal wave 8, primary creeping wave 9, and secondary creeping wave 10.
[0061] Figure 4 It includes secondary creeping wave 10, that is, inner surface creeping wave; large-angle longitudinal wave 11; shear wave waveform conversion wave 12, that is, angle reflection wave train.
[0062] Figure 8Including the tip diffraction signal 13 and the angular reflection signal 14.
[0063] Detection principle:
[0064] The creeping wave detection technology is a powerful supplement to the conventional ultrasonic detection technology, such as the detection of near-surface cracks in fillet welds or coatings, the blind-zone-free detection of thick-grained extruded pipes, and the detection of inner surface defects. The generation of creeping waves utilizes the waveform conversion that occurs when ultrasonic waves propagate to the interface of two heterogeneous media. According to the propagation characteristics of ultrasonic waves, when ultrasonic waves are obliquely incident from one medium to the interface of another medium, in addition to reflection, refraction will also occur in the transmitted wave, accompanied by waveform conversion. When the longitudinal wave incident angle in the probe wedge is equal to the first critical angle, creeping waves, that is, subsurface longitudinal waves, are generated in the workpiece.
[0065] From Figure 1 the schematic diagram of the sound field of the creeping wave probe shown, it can be seen that the sound field excited by the creeping wave probe has the characteristics of multi-wave types. When creeping waves are generated, transverse waves and head waves of about 33° are also generated. Figure 1 The main longitudinal wave in is the main sound beam of the creeping wave, and its angle is about 75°; the transverse wave propagates forward from the incident point of the probe at a refraction angle of about 33°; the head wave is the transverse wave continuously radiated during the forward propagation of the subsurface longitudinal wave, that is, the incident point of the head wave is not fixed. At the same time, primary creeping waves and secondary creeping waves can also be generated. The primary creeping wave is the creeping wave under the outer surface of the pipe, and the secondary creeping wave is the creeping wave under the inner surface of the pipe.
[0066] Detection probe design:
[0067] In order to effectively detect the open defects on the inner surface of the pipe, a single crystal probe is used to generate a 70° refracted longitudinal wave in the steel pipe. Since other wave types are also generated by the incident angle used for this 70° longitudinal wave, under the interaction of different waves, a unique wave of "echo pattern" is generated (as Figure 4 shown). This wave of "echo pattern" can detect defects at different depths on the inner surface of the pipe. There are mainly three mode recognition methods for secondary creeping waves (inner surface creeping waves), transverse wave waveform conversion waves (30° - 70° - 70°), and large-angle longitudinal waves (70°):
[0068] Secondary creeping waves (inner surface creeping waves): This wave is essentially a longitudinal wave propagating along the inner surface of the pipe. The subsurface creeping wave under the inner surface can detect open defects on the inner surface. This wave type is suitable for the detection of shallow surface defects.
[0069] Shear wave mode conversion wave (30°-70°-70°): Generates a 30° shear wave together with a 70° longitudinal wave. The 30° shear wave propagates to the bottom surface of the pipe and undergoes mode conversion to a 70° longitudinal wave. The mode-converted 70° wave is incident on the defect surface and then propagates back to the probe. This round-trip wave is also known as the "30°-70°-70°" angle reflection tandem wave, which is used to represent the angles of the triangular acoustic path. This wave mode is suitable for detecting medium and deeper defects.
[0070] Large angle longitudinal wave (70°): This is a 70° refracted longitudinal wave, which only appears when the defect is very deep. This wave mode is suitable for detecting very deep defects.
[0071] Detection calibration test block and artificial defect design:
[0072] Since creeping waves contain a relatively high energy level and propagate relatively close to the inner surface, creeping waves are extremely sensitive to defects near the inner surface of the pipe. Since it is not a true surface wave and does not follow the propagation law of the surface geometry, it is less sensitive to reflectors (such as the welding root), and these reflectors have strong echoes when using a shear wave probe. Therefore, a creeping wave probe can be used for detection and waveform discrimination.
[0073] It can accurately, quickly, and conveniently detect and identify and evaluate the defects on the inner surface of the pipe. A series of grooves with different depths will be cut on pipes of the same specification to judge the presence and approximate depth of the defects by the number and position of the echoes. When the specifications of the calibration test block and the material to be detected are equal, the grooves with different depths on the calibration test block can be used to detect and evaluate the defect depths in the 3 modes.
[0074] Generally, the groove depth will be in the range of 5% to 95% of the wall thickness. To effectively quantify the echoes of the three modes of secondary creeping waves, shear wave mode conversion waves (angle reflection tandem waves), and 70° longitudinal waves, the depths of the artificial grooves on the calibration test block are 5%, 30%, 60%, and 95% of the wall thickness respectively (as Figure 3 shown). Therefore, the range of the artificial groove depths corresponding to the three modes:
[0075] ① The depth range of the artificial groove for secondary creeping waves (inner surface creeping waves) is 5% to 35% of the wall thickness;
[0076] ② The depth range of the artificial groove for shear wave mode conversion waves (30°-70°-70°) is 30% to 70% of the wall thickness;
[0077] ③ The depth range of the artificial groove for large angle longitudinal waves (70°) is 60% to 95% of the wall thickness.
[0078] Detection method:
[0079] In order to effectively detect inner surface defects of pipelines, a detection probe is designed using the second surface creeping wave, which can generate three wave modes: the second surface creeping wave, the shear wave mode conversion (angle reflection tandem wave), and the large angle longitudinal wave (70°). The detection methods corresponding to these three wave modes are the tip diffraction detection method, the dual-mode detection method, and the large angle longitudinal wave detection method.
[0080] Tip diffraction detection method:
[0081] This method is applicable to determining the size of shallow defects penetrating 5 - 35% of the inner wall thickness. In this method, the arrival time of the signal from the defect tip is used to determine the defect depth. Calibration blocks with 5% and 30% slots can be used for comparison, as Figure 7 shown.
[0082] In addition, in this method, the tip diffraction signal should be distinguished from the angle reflection signal, as Figure 8 shown. To make the signal of the defect tip diffraction easy to distinguish, a highly damped 5 MHz, 45° or 60° shear wave probe is usually used. Since the signal from the defect tip diffraction may be relatively weak, the detector should have an RF display. When the signal-to-noise ratio is poor, the RF display can more easily see the defect tip diffraction signal, as Figure 9 shown.
[0083] Dual-mode detection method:
[0084] This method is applicable to determining the size of defects within the depth range of 30 - 70% of the inner wall thickness. Usually, a 3 MHz dual-crystal tandem probe is used. This probe uses the front crystal to excite a 50° refracted longitudinal wave and the associated shear wave, and uses the rear crystal to receive the echo. Calibration blocks with 60% slots can be used for comparison, as Figure 10 shown. The main difference from the tip diffraction method is the dual-mode method that combines the tip diffraction and the creeping wave method. Using this diffraction method, the separated echo signals of different modes are recorded and used in the evaluation / quantification process.
[0085] Large angle longitudinal wave detection method:
[0086] This method is applicable to determining the size of defects with a depth of approximately 60 - 95% of the wall thickness. This method again uses the arrival time of the signal from the defect tip diffraction as an indication of the defect depth. It should be noted that these indications show the remaining thickness of the good material in the pipeline, rather than the actual depth of the defect. It is recommended to use a dual-crystal large angle longitudinal wave probe in combination with this method. An outer surface first surface creeping wave probe can be used to detect defects that extend almost completely through the wall thickness, as Figure 11 shown.
[0087] Quantitative detection procedure:
[0088] Through non-destructive testing of the inner surface defects of pipelines, non-destructive testing methods for inner surface defects of pipelines are formed by applying different testing methods, defect location analysis, comparison with artificial defects, signal display, etc., enabling accurate quantification of corrosion / fatigue defects (cracks) on the inner surface of pipelines, and forming a quantitative detection procedure for inner surface defects of pipelines (such as Figure 12 shown), effectively quantitatively detecting inner surface defects of pipelines (such as corrosion fatigue cracks, etc.).
[0089] In some embodiments of the present invention, a non-destructive testing method for detecting inner surface defects of pipelines further includes:
[0090] (1) Design a detection probe. It can generate ultrasonic creeping waves (including primary creeping waves and secondary creeping waves), shear wave mode conversion waves (30°-70°-70°), and large-angle longitudinal waves (70°).
[0091] (2) Design a detection calibration block and artificial defects. The depths of the artificial grooves (inner grooves) of the calibration block are 5%, 30%, 60%, and 95% of the wall thickness respectively, for comparing the actual defect depths.
[0092] (3) Form a detection method. Mainly apply three methods: tip diffraction detection, dual-mode detection, and large-angle longitudinal wave detection, to form a quantitative detection procedure for inner surface defects of pipelines.
[0093] Through the detection of inner surface defects of pipelines (such as corrosion fatigue cracks, etc.), mainly from the design of the detection probe, the design of the detection calibration block and artificial defects, and the application of the tip diffraction detection method, dual-mode detection method, and large-angle longitudinal wave detection method, the corrosion / fatigue cracks on the inner surface of pipelines can be effectively detected, providing important support for the quantitative technology of pipeline corrosion / fatigue cracks. It can also quantitatively and qualitatively detect inner surface defects of pipelines or other devices in places or conditions where other detection methods such as high altitude, narrow spaces, and no power supply cannot reach.
[0094] The above description and the accompanying drawings fully illustrate the embodiments of the present disclosure, enabling those skilled in the art to practice them. Other embodiments may include structural and other changes. The embodiments only represent possible variations. Unless explicitly required, individual components and functions are optional, and the order of operations can vary. Parts and features of some embodiments may be included in or replace parts and features of other embodiments. The embodiments of the present disclosure are not limited to the structures already described and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present disclosure is only limited by the appended claims.
Claims
1. A non-destructive testing method for detecting defects on the inner surface of a pipeline, characterized in that, Including: Detecting inner surface defects of the pipeline by using a detection method based on a secondary creeping wave detection probe; Designing a detection calibration test block; Comparing the detected inner surface defects with the detection calibration test block, analyzing the defect positions, and obtaining signal waveforms; Evaluating the inner surface defects of the pipeline based on the signal waveforms.
2. The non-destructive testing method for detecting defects on the inner surface of a pipeline according to claim 1, characterized in that, The detection methods include three types, namely the tip diffraction method, the dual-mode method, and the large-angle longitudinal wave method.
3. The non-destructive testing method for detecting defects on the inner surface of a pipeline according to claim 2, characterized in that The depths of the inner grooves in the calibration test block include 4 types, namely 5%, 30%, 60%, and 95% of the wall thickness.
4. The non-destructive testing method for detecting defects on the inner surface of a pipeline according to claim 1, characterized in that, The defect position analysis and obtaining the signal waveforms include: Suspicious shallow defect signal waveforms, suspicious intermediate layer defects, and suspicious deep layer defects.
5. The non-destructive testing method for detecting defects on the inner surface of a pipeline according to claim 2, characterized in that, The waveforms obtained by comparing the detected defects with the detection calibration test block include: secondary creeping wave waveforms, secondary creeping wave and angle reflection wave waveforms, secondary creeping wave and angle reflection wave waveforms, secondary creeping wave and shear wave waveform conversion wave waveforms; secondary creeping wave, shear wave waveform conversion wave and large-angle longitudinal wave waveforms.
6. The non-destructive testing method for detecting defects on the inner surface of a pipeline according to claim 2, characterized in that, The tip diffraction method determines the defect depth based on the signal arrival time at the defect tip and is used to determine the size of shallow defects with a depth of 5-35% of the wall thickness passing through the inner groove; among them, the specifications of the detection calibration test block used are: the depths of the inner grooves are 5% and 30% of the wall thickness. The secondary creeping wave detection probe is a 5MHz, 45° or 60° shear wave probe with high damping, and a radio frequency display is provided in the probe.
7. The non-destructive testing method for detecting defects on the inner surface of a pipeline according to claim 2, characterized in that, The dual-mode method is used to determine the size of defects with a depth of 30-70% of the wall thickness passing through the inner groove.
8. The non-destructive testing method for detecting defects on the inner surface of a pipeline according to claim 2, characterized in that, The large-angle longitudinal wave method indicates the thickness of the remaining good material in the pipeline based on the signal arrival time at the defect tip and is used to determine the size of defects with a depth of 60-95% of the wall thickness passing through the inner groove.