A corrosion monitoring and early warning method

Abstract

This invention discloses a corrosion monitoring and early warning method, including a corrosion probe device and a signal acquisition processor. This invention integrates two technologies: electrochemical noise monitoring and acoustic emission monitoring, as well as probe monitoring and body monitoring. It employs the mutual corroboration of characteristic signals from electrochemical noise and acoustic emission, simultaneously performing probe monitoring and equipment monitoring. By combining probe and equipment monitoring, the corrosion behavior of the monitored equipment / pipeline is jointly determined, improving the accuracy of monitoring and early warning. Furthermore, to address various potential corrosion types, stress, gradual crevice, welded joints, and dissimilar metals are flexibly introduced into the monitoring probe. This allows for the simultaneous consideration of multiple corrosion types, such as stress corrosion, pitting corrosion, crevice corrosion, and galvanic corrosion, providing a preliminary judgment of the corrosion type while simultaneously issuing an early warning of the corrosion state.

Description

Technical Field

[0001] This application relates to the field of pipeline corrosion risk monitoring, specifically to a corrosion monitoring and early warning method. Background Technology

[0002] Pitting corrosion and stress corrosion cracking are common forms of localized damage to metallic materials. Furthermore, the insidious nature of early-stage corrosion makes them difficult to detect using conventional methods, often contributing significantly to equipment / pipeline failures and easily leading to leaks, fires, and explosions. Therefore, effective monitoring of the corrosion process is of paramount importance. Acoustic emission and electrochemical technologies are common non-destructive testing methods, offering advantages such as high sensitivity, non-destructive nature, and real-time online monitoring. However, they also suffer from drawbacks such as complex interference signals and a high false alarm rate, severely reducing the effectiveness of field applications and hindering technological development. Some researchers have attempted a combination of the two methods. Patent CN115901881A provides a method, device, equipment, and storage medium for monitoring stress corrosion cracking. It monitors pitting and microcrack initiation events in the first stage of stress corrosion cracking of the tubing steel sample through electrochemical noise signals; and monitors crack propagation and crack tearing events in the second stage of stress corrosion cracking of the tubing steel sample through acoustic emission signals. The main purpose is to improve the accuracy of monitoring by leveraging the different sensitive stages of stress corrosion of the two methods. It is not a fusion of the two methods, does not mention the algorithm for combining the two methods, and is only applicable to laboratory samples, not to field equipment. Summary of the Invention

[0003] Based on the above problems, this application addresses the issues of high interference and false alarm rates associated with single electrochemical noise monitoring and single acoustic emission monitoring, as well as the drawback of simple combined electrochemical noise and acoustic emission probes not directly reflecting the condition of the tested equipment / pipeline. Therefore, it proposes a corrosion monitoring and early warning method, the technical solution of which is as follows:

[0004] A corrosion monitoring and early warning method includes a corrosion probe device and a signal acquisition processor. The corrosion probe device includes two specimens of the same material, with two insulating pads between the two specimens and a reference electrode between the two insulating pads. Each specimen has a bent portion and a loading bolt. A pre-drilled circular hole is provided in each specimen, through which the loading bolt passes. The loading bolt is fitted into an insulating sleeve and passes through the pre-drilled hole in both specimens. Pre-loading of the specimens is achieved by rotating a nut. The ends of the two specimens are fitted into a sleeve. One of the specimens has an acoustic sensor. Wires from the two specimens, the reference electrode, and the acoustic sensor are led out from the sleeve and connected to the signal acquisition processor. At least one acoustic sensor is installed on the outer wall of the device under test and connected to the signal acquisition processor. The signal acquisition processor analyzes and judges the corrosion state of the device under test by acquiring information from the corrosion probe device and the sensor installed on the device under test, and issues an early warning based on the calculation results.

[0005] Preferably, the corrosion state of the device under test is represented by a state value H, which is determined by the corrosion factor Z and the acoustic characteristic factor S of the device. The corrosion factor Z is set to X × Y. The signal acquisition processor acquires the electrochemical signal of the sample and marks it as the probe electrochemical factor X. The acoustic signal of the acoustic sensor in the corrosion probe device is marked as the monitoring probe acoustic characteristic factor Y.

[0006] Preferably, the probe electrochemical factor X is the product of the trend factor Q and the difference factor W, i.e., X = Q × W. The trend factor Q is related to the linear fitting slope of the linear segment of the noise signal in the frequency domain. If the slope is <10, X is 1; if the slope is [10~20], X is 0.6~0.9; if the slope is >20, X is 0~0.2. The difference factor W is related to the similarity or difference in the current between the specimens and the voltage change trends between the specimens and the reference electrode in the corresponding time period. If the same direction is W = 0~0.2, and if the opposite direction is W, it is 0.8~1.6.

[0007] Preferably, the probe acoustic wave characteristic factor Y includes an attenuation factor A and a span factor B, i.e., Y = A × B; the attenuation factor A is the ratio of the slope of the linear fitting curve of the peak point of the characteristic waveform in the rising or falling phase to the slope of the corresponding fitting curve of the characteristic waveform in the feature library, or the average of four corresponding ratios; the span factor B is the product of the ratios of the normalized spacing of the troughs in the rising or falling phase.

[0008] Preferably, the acoustic characteristic factor S of the device includes a pictographic factor C, a positional repetition factor D, and a frequency factor E, i.e., S = C × D × E;

[0009] Pictographic factor C: The shape similarity between the acoustic waveform of the acoustic sensor installed on the device under test and the characteristic waveform of the probe acoustic waveform of the corrosion probe device. It takes a value between 0 and 1, and the higher the similarity, the closer the value is to 1.

[0010] Position repetition factor D: Obtain the acoustic signal time through acoustic sensors distributed on the outer wall of the device to be measured, locate the sound source position, and determine the value of D according to the concentration degree of the occurrence positions. The more concentrated the area, the larger the value of D. The value range is 0 - 1.5. When the positioning cannot be obtained, take D = 1;

[0011] Frequency factor E: It is the correlation between the intervals of the same type of sound waves obtained by the acoustic sensors on the outer wall of the device to be measured and the intervals of the sound waves obtained by the sensors in the corrosion probe device. The higher the correlation, the larger the value. The value range is 0.5 - 1.

[0012] Preferably, the corrosion state value H of the device is jointly determined by the value of the corrosion factor Z and the acoustic wave characteristic factor S of the monitoring device. The corrosion state value H includes four categories, namely "high", "relatively high", "medium" and "low", as follows:

[0013] a < Z and a < S, H = high,

[0014] b < Z ≤ a, and a < S, H = relatively high,

[0015] a < Z and b < S ≤ a, H = relatively high,

[0016] b < Z ≤ a and b < S ≤ a, H = medium

[0017] Z ≤ b or S ≤ b, H = low

[0018] Where a and b are set classification constants. The value range of a is 0.7 - 0.9, and the value range of b is 0.3 - 0.5;

[0019] Send a warning according to the H value result and the set alarm value.

[0020] Preferably, the specimen is one of U-shaped, C-shaped or polygonal, and the material is made of the same metal or dissimilar metal welding material. The welded joint is arranged at the middle of the bending part or at the junction of the bending and non-bending parts.

[0021] Preferably, a reference electrode is placed between two insulating pads; the width of the insulating pad should not be less than the width of the specimen. The connection part of the reference electrode and the wire is placed at the position where the specimen starts to bend at the upper part, and the exposed part of the wire connection is sealed with insulating glue.

[0022] Preferably, the thickness of each of the insulating pads is 0.1 - 3 mm.

[0023] Beneficial effects

[0024] Compared with existing technologies, electrochemical signals and acoustic emission signals are different signals generated by the same behavior on the same specimen, exhibiting good correspondence characteristics and time correlation. The fusion analysis of electrochemical noise signals and acoustic signals easily distinguishes corrosion information from noise information, enhancing anti-interference capabilities. Furthermore, the fusion analysis of information collected by sensors on the probe and acoustic sensors on the device / pipeline under test further improves anti-interference capabilities and the specificity of the assessment. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the corrosion probe device.

[0026] Figure 2 This is a side view of the corrosion probe device structure.

[0027] Figure 3 This is a schematic diagram for use in this application.

[0028] In the figure, 1-1 Specimen, 1-11 Bending section, 1-2 Loading bolt, 1-3 Reference electrode, 1-4 Insulating pad, 1-5 Insulating gasket, 1-6 Insulating sleeve, 1-7 Sleeve, 1-8 Built-in acoustic sensor, 1-9 Flange, 2- External acoustic sensor, 3- Signal acquisition processor, 4- Device under test, 7- Cable. Detailed Implementation

[0029] The following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application.

[0030] A corrosion monitoring and early warning method includes a corrosion probe device and a signal acquisition processor. The corrosion probe device includes two specimens 1-1 of the same material, with two insulating pads 1-4 between the two specimens. A reference electrode 1-3 is positioned between the two insulating pads 1-4. Each specimen has a bent portion 1-11 and a loading bolt 1-2. The portion of the loading bolt 1-2 that contacts the specimen 1-1 is fitted within an insulating sleeve 1-6. The loading bolt 1-2 passes through the two specimens 1-1 and is tightened by rotating a nut to achieve corrosion monitoring and early warning. Preloaded, the ends of two test pieces are fitted into sleeve 1-7, with an acoustic sensor 1-8 mounted on one of the test pieces 1-1. The wires of the two test pieces 1-1, the reference electrode 1-3, and the acoustic sensor (marked as built-in acoustic sensor 1-8) are led out from sleeve 1-7 and connected to the signal acquisition processor. At least one other acoustic sensor (external acoustic sensor 2) is mounted on the outer wall of the device under test and connected to the signal acquisition processor. A flange 1-9 is welded to the other end of sleeve 1-7, connecting and sealing it to a pre-fabricated connecting pipe on the device under test 4. The signal acquisition processor 3 acquires the acoustic signals from the device under test. The signal acquisition processor consists of an electrochemical signal acquisition unit, an acoustic signal acquisition unit, a control unit, and a display unit. Both the external acoustic sensor 2 and the built-in acoustic sensor 1-8 are connected to the acoustic signal acquisition unit in the signal acquisition and analysis system. The connecting wires of the two test pieces are connected to the electrochemical signal acquisition unit in the signal acquisition and analysis system, and the two test pieces are connected to the working electrode terminal and the counter electrode terminal, respectively. The reference electrode 1-3 is connected to the reference electrode terminal. The signal acquisition processor comprehensively judges the corrosion status of the device under test by acquiring information from the corrosion probe device and the external acoustic sensor 2 installed on the device under test, and issues an early warning based on the calculation results.

[0031] During operation, the signal acquisition and analysis system simultaneously collects electrochemical noise signals and acoustic signals generated by the corrosion probe. Since both electrochemical and acoustic emission signals are different signals caused by the same behavior on the same specimen, they exhibit good correspondence and temporal correlation. The fusion analysis of electrochemical and acoustic signals easily distinguishes between correlated corrosion information and uncorrelated noise information, enhancing anti-interference capabilities. Furthermore, the corrosion probe device introduces stress and crevice conditions, and welding conditions can be introduced by welding the specimen, allowing for a closer simulation of the actual environmental conditions of the equipment / pipeline. In addition, acoustic sensors are installed on the device itself. The various corrosion and noise signal characteristics extracted from the corrosion probe device can be used for noise filtering and feature recognition of signals captured by the acoustic sensors on the device under test, further improving anti-interference capabilities and significantly reducing false alarm rates. This enables online monitoring of various corrosion forms on the tested equipment, including uniform corrosion, pitting corrosion, crevice corrosion, and stress corrosion cracking.

[0032] Installation method:

[0033] Specimen 1-1 consists of two identical specimens. The specimens can be U-shaped, C-shaped, polygonal, or other shapes suitable for loading. The specimens can be made of a homogeneous material or a welded material of the same or dissimilar metals. Preferably, the weld joint is located in the middle of the bent portion or at the junction of the bent and non-bent portions. The specimens are placed back-to-back with their longer sides facing each other, with two layers of insulating pads 1-4 placed in between. The reference electrode 1-3 and its wire are placed between the two insulating pads. The width of the two insulating pads should not be less than the width of the specimen. The position of the reference electrode and the specimen is adjusted. Preferably, the connection between the reference electrode and the wire is placed at the upper part of the specimen where the bend begins. The exposed part of the wire connection is sealed with insulating adhesive. The distance between the two specimens and the size of the gap between the specimen and the surface of the insulating pad / reference electrode are adjusted by adjusting the thickness of the insulating pads. The gap size is controlled between 0.1 and 3 mm. Insert insulating gaskets 1-5 onto loading bolts 1-2 and insulating sleeves 1-6 into the openings in the specimen. Tighten the bolts passing through the specimen with nuts. Control the deformation of the specimen by tightening the nuts according to the required stress. Typically, it is necessary to load until local plastic deformation occurs, thereby introducing stresses from 0 to σ on the specimen. s Gradual stress condition (yield strength). Connect the loaded specimen with wires, sealing the connection points with insulating adhesive. The longer end of the specimen, along with the wires connecting the specimen and the electrode, extends into sleeve 1-7. An internal acoustic sensor 1-8 is installed on the long side of one of the specimens. A thin layer of coupling agent is applied between the acoustic sensor and the specimen to maintain good contact. After passing a local lead breakage test, it is sealed and fixed with sealant. For easy disassembly, a housing can be fitted over the sensor for sealing. An elastic clamping device, such as a spring or spring sheet, is placed between the housing and the sensor. The connection and sealing between sleeve 1-7 and the loaded specimen 1-1 are achieved by squeezing the sealing ring or injecting sealant. The specific connection and sealing method must be selected based on the operating pressure and temperature.

[0034] The signal cables and electrode wires of the built-in acoustic sensors 1-8, as well as the connecting wires on the test specimen, are all led out through sleeves 1-7 and connected to the pre-fabricated pipe fittings on the device under test 4 via flanges to achieve a seal. The led-out cables are connected to the signal acquisition and processing system 3. The built-in acoustic sensors are connected to the acoustic signal acquisition unit in the signal acquisition and analysis system. The sample with the built-in acoustic sensor is connected to the working electrode of the electrochemical signal acquisition unit in the signal acquisition and analysis system 3 via a wire. Another sample is connected to the counter electrode of the electrochemical signal acquisition unit in the signal acquisition and analysis system via a wire. The reference electrode is connected to the reference electrode of the electrochemical signal acquisition unit in the signal acquisition and analysis system via a wire. Then, based on the characteristics and structural dimensions of the internal medium of the device / pipe under test, external acoustic sensors are arranged. The specific placement, quantity, and sensor selection need to be selected and optimized according to the actual situation on site, such as the corrosion location, the size of the monitored area, and the sound attenuation. This is standard operation and will not be elaborated further. The acoustic sensor 2, arranged on the surface of the device or pipe under test, is also connected to the acoustic signal acquisition unit in the signal acquisition and analysis system 3 via cables. After the arrangement and signal verification are completed, monitoring and data recording can begin.

[0035] The data acquisition and analysis system will perform fusion analysis and noise reduction on the collected information, and will issue alarms and display abnormal information. The specific methods are as follows:

[0036] The corrosion state of the device under test is represented by the state value H, which is determined by the corrosion factor Z and the acoustic characteristic factor S of the device. The corrosion factor Z is set to X × Y. The signal acquisition processor acquires the electrochemical signal of the sample and marks it as the probe electrochemical factor X. The acoustic signal of the acoustic sensor in the corrosion probe device is marked as the monitoring probe acoustic characteristic factor Y.

[0037] The probe electrochemical factor X is the product of the trend factor Q and the difference factor W, i.e., X = Q × W. The trend factor Q is related to the linear fitting slope of the linear segment of the noise signal in the frequency domain. If the slope is <10, X is 1; if the slope is [10~20], X is 0.6~0.9; if the slope is >20, X is 0~0.2. The difference factor W is related to the similarity or difference in the current between the specimens and the voltage change trends between the specimens and the reference electrode in the corresponding time period. If the same direction is W = 0~0.2, and if the opposite direction is W, it is 0.8~1.6.

[0038] The probe acoustic wave characteristic factor Y includes attenuation factor A and span factor B, i.e., Y = A × B; attenuation factor A is the ratio of the slope of the linear fitting curve of the peak point of the characteristic waveform in the rising or falling phase to the slope of the corresponding fitting curve of the characteristic waveform in the feature library, or the average of four corresponding ratios; span factor B is the product of the ratios of the normalized spacing of the troughs in the rising or falling phase.

[0039] The acoustic wave characteristic factor S of the device includes the pictorial factor C, the position repetition factor D, and the frequency factor E, that is, S = C × D × E;

[0040] Pictorial factor C: The shape similarity between the acoustic wave form obtained by the acoustic sensor installed on the device to be measured and the probe acoustic wave characteristic waveform of the corrosion probe device, which takes values between 0 and 1. The higher the similarity, the closer the value is to 1;

[0041] Position repetition factor D: Obtain the acoustic signal time through the acoustic sensors distributed on the outer wall of the device to be measured, locate the sound - emitting position, and determine the value of D according to the concentration degree of the occurrence positions. The more concentrated the area, the larger the value of D, and the value range is 0 - 1.5; when the positioning cannot be obtained, take D = 1;

[0042] Frequency factor E: It is the correlation between the interval of the same type of acoustic waves obtained by the acoustic sensors on the outer wall of the device to be measured and the interval of the acoustic waves obtained by the sensors in the corrosion probe device. The higher the correlation, the larger the value, and the value range is 0.5 - 1.

[0043] Determine the device corrosion state value H jointly through the value of the corrosion factor Z and the device acoustic wave characteristic factor S. The corrosion state value H includes four categories, namely "high", "relatively high", "medium", and "low", as follows:

[0044] a < Z and a < S, H = high,

[0045] b < Z ≤ a, and a < S, H = relatively high,

[0046] a < Z and b < S ≤ a, H = relatively high,

[0047] b < Z ≤ a and b < S ≤ a, H = medium

[0048] Z ≤ b or S ≤ b, H = low

[0049] Where a and b are set classification constants, the value range of a is 0.7 - 0.9, and the value range of b is 0.3 - 0.5; Send early warnings according to the H - value result and the set alarm value.

[0050] The present invention is applicable to corrosion scenarios such as uniform corrosion, pitting corrosion, stress corrosion, crevice corrosion, galvanic corrosion, etc., and can be widely applied to many industries such as petrochemical, electric power, new energy, etc., and has a very broad application prospect.

Claims

1. A corrosion monitoring and early warning method, characterized in that, The device includes a corrosion probe device and a signal acquisition processor. The corrosion probe device includes two specimens of the same material, with two insulating pads between the two specimens and a reference electrode between the two insulating pads. Each specimen has a bent portion and a loading bolt. The portion of the loading bolt that contacts the specimen is fitted inside an insulating sleeve. The loading bolt passes through the two specimens and is preloaded by rotating a nut. The ends of the two specimens are fitted inside a sleeve. One of the specimens has an acoustic sensor. The wires of the specimen, the reference electrode, and the acoustic sensor are led out from the sleeve and connected to the signal acquisition processor. At least one acoustic sensor is installed on the outer wall of the device under test and connected to the signal acquisition processor. The signal acquisition processor analyzes and judges the corrosion status of the equipment under test by acquiring information from the corrosion probe device and the sensors installed on the equipment under test, and issues early warnings based on the calculation results; The corrosion state of the device under test is represented by the state value H, which is determined by the corrosion factor Z and the acoustic characteristic factor S of the device. The corrosion factor Z is set as X×Y. The signal acquisition processor acquires the electrochemical signal of the sample and marks it as the probe electrochemical factor X. The acoustic signal of the acoustic sensor in the corrosion probe device is marked as the monitoring probe acoustic characteristic factor Y. The probe electrochemical factor X is the product of the trend factor Q and the difference factor W, i.e., X = Q × W. The trend factor Q is related to the linear fitting slope of the linear segment of the noise signal in the frequency domain. If the slope is <10, X is 1; if the slope is [10~20], X is 0.6~0.9; if the slope is >20, X is 0~0.

2. The difference factor W is related to the current between the specimens and the voltage change trends between the specimens and the reference electrode in the corresponding time period. W = 0~0.2 in the same direction and W = 0.8~1.6 in the opposite direction. The probe acoustic wave characteristic factor Y includes attenuation factor A and span factor B, i.e., Y = A × B; attenuation factor A is the ratio of the slope of the linear fitting curve of the peak point of the characteristic waveform in the rising or falling phase to the slope of the corresponding fitting curve of the characteristic waveform in the feature library, or the average of four corresponding ratios; span factor B is the product of the ratios of the normalized spacing of the troughs in the rising or falling phase. The acoustic characteristic factor S of the equipment includes the pictographic factor C, the positional repetition factor D, and the frequency factor E, i.e., S = C × D × E; Pictographic factor C: The shape similarity between the acoustic waveform of the acoustic sensor installed on the device under test and the characteristic waveform of the probe acoustic waveform of the corrosion probe device. It takes a value between 0 and 1, and the higher the similarity, the closer the value is to 1. Location repetition factor D: The acoustic signal time is obtained by acoustic sensors distributed on the outer wall of the device under test to locate the sound source. The value of D is determined according to the concentration of the sound source. The more concentrated the area, the larger the value of D. The value range is 0-1.

5. When the location cannot be obtained, D=1. Frequency factor E: The correlation between the interval of similar sound waves obtained by the acoustic sensor on the outer wall of the device under test and the interval of sound waves obtained by the acoustic sensor inside the corrosion probe device. The higher the correlation, the larger the value, with a range of 0.5 to 1. The corrosion state value H of the device is jointly determined by the value of the corrosion factor Z and the acoustic wave characteristic factor S of the device. The corrosion state value H includes four categories, namely "high", "relatively high", "medium" and "low", which are specifically as follows: a < Z and a < S, H = high; b < Z ≤ a, and a < S, H = relatively high; a < Z and b < S ≤ a, H = relatively high; b < Z ≤ a and b < S ≤ a, H = medium; Z ≤ b or S ≤ b, H = low; Where a and b are set classification constants, the value range of a is 0.7 - 0.9, and the value range of b is 0.3 - 0.5; An early warning is sent according to the H value result and the set alarm value.

2. The corrosion monitoring and early warning method according to claim 1, characterized in that, The specimen is one of U-shaped, C-shaped or polygonal. The specimen is a homogeneous material or a heterogeneous material with a welded joint. The heterogeneous material is welded by the same metal or dissimilar metals. The welded joint is arranged in the middle of the bending part or at the junction of the bending and non-bending parts.

3. The corrosion monitoring and early warning method according to claim 1, characterized in that, The width of the insulating pad should not be less than the width of the specimen. The part where the reference electrode is connected to the wire is placed at the position where the specimen starts to bend at the upper part. The exposed part of the wire connection is sealed with insulating glue.

4. The corrosion monitoring and early warning method according to claim 1, characterized in that, There is a gradually increasing opening gap area between adjacent parts of the two specimens. The width of the gap formed between the two specimens is adjusted by the thickness of the insulating pad. The thickness of the insulating pad is 0.1 - 3 mm.

5. The corrosion monitoring and early warning method according to claim 1, characterized in that, The preloading of the specimen is controlled by rotating the nut, and gradually changing different stress conditions are introduced at different parts of the specimen.

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