Pipeline crack corrosion monitoring method based on multi-way alternate current potential drop

A technology for alternating current and corrosion detection, which is applied in the direction of measuring devices, material analysis through electromagnetic means, instruments, etc., can solve problems such as limiting the detection range of crack defects, and achieve improved crack depth and solution accuracy, strong anti-interference ability, and excitation current small effect

Active Publication Date: 2018-10-19
SICHUAN UNIV
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Problems solved by technology

[0003] At present, commonly used pipeline corrosion detection technologies, including the relatively advanced Field Signature Method (FSM), only have high detection accuracy for localized corrosion and general corrosion; the latest AC field fingerprint technology Alternating Current Field Signature Method (ACFSM), using the measurement data of multiple frequency points to evaluate the corrosion depth, can improve the detection accuracy of crack corrosion, but this method requires that the angle between the crack direction and the current electrode connection direction is greater than 45 degrees, and cannot To solve cracks with an included angle of less than 45 degrees, the connection direction of the current excitation electrode is parallel to the pipeline axis, which will limit the detection range of crack defects

Method used

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  • Pipeline crack corrosion monitoring method based on multi-way alternate current potential drop
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  • Pipeline crack corrosion monitoring method based on multi-way alternate current potential drop

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Experimental program
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Effect test

Embodiment 1

[0081] 3. Embodiment 1. Utilize a plate model to carry out simulation test

[0082] The flat plate model is firstly solved accurately.

[0083] The length of the plate is 220mm, the width is 220mm, the thickness is 10mm, the distance between the measuring probes is 20mm, the amplitude of the injected current is 2A, and the frequency is 100HZ. For details, see Figure 6 shown.

[0084] The defect depth is 2mm, 2.5mm, 3mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, and the material parameters are as follows in Table 2:

[0085]

[0086]

[0087] Taking the 0-degree crack defect and the 45-degree crack defect as examples, the measurement results obtained by the two under the above simulation conditions are:

[0088] Take the value of 0 degree defect for depth fitting, the formula is:

[0089]

[0090] The results calculated by formula (7) for 45-degree defects are shown in Table 2 above.

Embodiment 2

[0091] Embodiment 2 utilizes 5 aluminum plates to do the test

[0092] Experimental materials: 5 aluminum plates of 220mm×220mm×10mm, the overall experimental device is as follows Figure 7-8 shown.

[0093] Before unprocessed defects, followed by I in1 , I in2 , I in3 , I in4 The electrode injects 2A, 100Hz alternating current into the plate, such as Figure 5 , Figure 8 As shown, the probe pairs (P 1 -P 2 ), (P 1 -P 3 ), (P 2 -P 3 ), (P 2 -P 4 ) between the original voltage U 1(d＝0) , U 2(d＝0) , U 3(d＝0) , U 4(d＝0) .

[0094] Then, 5 cracks were drawn on the bottom of the 5 plates respectively, among which No. 1-3 plates are 0 degree crack defects, the depths are 2mm, 4mm, 6mm respectively, and the width is 2mm; No. 4-5 plates are 45 degree crack defects , the depth distribution is 3mm, 5mm, such as Figure 9 shown.

[0095] Then, by I in1 , I in2 , I in3 , I in4 electrodes, see e.g. Figure 8 As shown, 2A current and 59-500Hz alternating current c...

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Abstract

The invention provides a pipeline crack corrosion monitoring method based on multi-way alternate current potential drop. The invention firstly provides a multi-way current method, excitation current is switched on from four different directions, then four sets of voltage ratios are obtained, the maximum voltage ratio is selected to be substituted in a depth solution formula according to the relation between the electrode crack direction and the voltage ratio, and thus the depth of the crack is obtained through solution. The multi-way current method enables the included angle (complementary angle) range between the crack position and the current electrode connection line to change from 0-90 degrees to 67.5-90 degrees, and thus the precision of the solution of the crack depth is obviously improved.

Description

technical field [0001] The invention belongs to the technical field of pipeline detection, and in particular relates to a pipeline crack corrosion monitoring method based on multidirectional alternating current potential drop. Background technique [0002] Pipeline corrosion is the most dangerous of many risks faced by oil and gas pipelines, and 70%-90% of pipeline safety accidents are caused by pipeline corrosion. [0003] At present, commonly used pipeline corrosion detection technologies, including the relatively advanced Field Signature Method (FSM), only have high detection accuracy for localized corrosion and general corrosion; the latest AC field fingerprint technology Alternating Current Field Signature Method (ACFSM), using the measurement data of multiple frequency points to evaluate the corrosion depth, can improve the detection accuracy of crack corrosion, but this method requires that the angle between the crack direction and the current electrode connection dir...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N27/00
CPCG01N27/00
Inventor 甘芳吉黄仕磊李文洋
Owner SICHUAN UNIV
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