Research on Features of Pipeline Crack Signal Based on Weak Magnetic Method

Liu, Bin; Liu, Ziqi; Luo, Ning; He, Limin; Ren, Jinchang; Zhang, He

doi:10.3390/s20030810

Cited by 5 publications

(3 citation statements)

References 24 publications

(24 reference statements)

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“…In the process of pipeline transportation, the internal pressure of the pipeline is within the range of 5~10 MPa, and the stress concentration area at the defect is remarkably larger than that in the other areas [ 40 ]. Therefore, the corresponding relationship between the stress at the defect and the internal pressure is formulated as follows [ 41 , 42 ]:

where Q is expansion coefficient, p is the internal pressure, R is the radius of pipeline, t is the wall thickness of the pipeline, and D y is the defect depth. In addition, F is the stress intensity factor at the crack tip and only depends on the crack size and internal pressure.…”

Section: Calculation and Analysismentioning

confidence: 99%

The Signal Characteristics of Oil and Gas Pipeline Leakage Detection Based on Magneto-Mechanical Effects

Liu

et al. 2023

Sensors

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In order to solve the problem of the quantification of detection signals in the magnetic flux leakage (MFL) of defective in-service oil and gas pipelines, a non-uniform magnetic charge model was established based on magnetic effects. The distribution patterns of magnetic charges under different stresses were analyzed. The influences of the elastic load and plastic deformation on the characteristic values of MFL signals were quantitatively assessed. The experimental results showed that the magnetic charge density was large at the edges of the defect and small at the center, and approximately decreased linearly with increasing stress. The eigenvalues of the axial and radial components of the MFL signals were compared, and it was found that the eigenvalues of the radial component exhibited a larger decline rate and were more sensitive to stress. With the increase in the plastic deformation, the characteristic values of the MFL signals initially decreased and then increased, and there was an inflection point. The location of the inflection point was associated with the magnetostriction coefficient. Compared with the uniform magnetic charge model, the accuracy of the axial and radial components of the MFL signals in the elastic stage of the improved magnetic charge model rose by 17% and 16%, respectively. The accuracy of the axial and radial components of the MFL signals were elevated by 9.15% and 9%, respectively, in the plastic stage.

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Section: Calculation and Analysismentioning

confidence: 99%

The Signal Characteristics of Oil and Gas Pipeline Leakage Detection Based on Magneto-Mechanical Effects

Liu

et al. 2023

Sensors

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“…Assuming that the length of the stress concentration region at both ends of the defect is b along the X direction. According to the stress distribution of the defect under load, the stress at the axial section of the defect is the largest, and gradually decreases to the average stress level of the pipeline with the distance from the end face of the defect [ 18 ]. Considering the variation of magnetic properties of materials caused by the stress concentration phenomenon, the MFL detected signal is the leakage magnetic field of stress region and defect.…”

Section: Numerical Model Of Composite Defectmentioning

confidence: 99%

Quantitative Study on MFL Signal of Pipeline Composite Defect Based on Improved Magnetic Charge Model

Liu

Luo

Gang

2021

Sensors

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Pipeline magnetic flux leakage (MFL) internal detection technology is the most widely used and effective method in the field of long-distance oil and gas pipeline online detection. With the improvement of data quantization precision, the influence of stress on MFL signal has been paid more and more attention. In this paper, the relationship between stress and saturation magnetization is introduced based on J-A theory. The analytical model of MFL detection signal for pipeline composite defects is established. The MFL signal characteristics of composite defects are quantitatively calculated. The effect of stress on MFL signal is studied. The theoretical analysis is verified by experimental data and excavation results. The researches show that the saturation magnetization of ferromagnets decreases exponentially with the increase of stress in strong magnetic field. The MFL signal of composite defect is weaker than that of volumetric defects of the same dimension. The axial amplitude and radial peak-to-peak value of MFL signal decrease with the increase of stress around the defect. The axial amplitude and radial peak-to-peak value of MFL signal increase non-linearly with the increase of width and depth of defects. When using MFL signal to judge the defect depth, it is necessary to make clear whether there is stress concentration phenomenon around the defect because the stress will lead to underestimation of the defect depth.

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“…In order to analyze the force on the magnetic particles present in the suspension, the magnetic field distribution on the workpiece surface, especially the magnetic field leakage distribution above a crack, was first determined. This magnetic field leakage directly determines the final aggregation of the magnetic particles present in a suspension [18]. The magnetic dipole model was used to calculate the crack magnetic field leakage distribution.…”

Section: Static Modelsmentioning

confidence: 99%

Investigation on the Formation Mechanism of Crack Indications and the Influences of Related Parameters in Magnetic Particle Inspection

Yang

Cai

et al. 2020

Applied Sciences

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The recent rapid development of industrial cameras and machine learning has brought new vitality to the very traditional flaw detection method, namely, magnetic particle inspection (MPI). To fully develop automatic fluorescent MPI technology, two main issues need to be solved urgently—the lack of theoretical analysis on the formation of the crack indications, and quantitative characterization methods to determine the crack indications. Here, we carry out a theoretical analysis and an experimental approach to address these issues. Theoretical models of the acting force of the leakage magnetic field were established. Subsequently, the impacts of different magnetic field strengths (1000–9000 A/m) and magnetic particle concentrations (0.5–30 mL/L) on the adsorption critical distance were analyzed. The models were solved by numerical calculations in MATLAB. In addition, a single variable control experiment was conducted to study the effects of crack images. In order to determine the quality of the crack image, three characteristic parameters were investigated, such as indication gray scale, background gray scale, and contrast ratio, were provided. The theoretical magnetic particle concentration range provided a guidance value for automated fluorescent MPI. Experimental results revealed that the optimal magnetic particle concentration was 3–4 mL/L, and, under this condition, the contrast between the crack indications and the background of crack images was obvious.

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Research on Features of Pipeline Crack Signal Based on Weak Magnetic Method

Cited by 5 publications

References 24 publications

The Signal Characteristics of Oil and Gas Pipeline Leakage Detection Based on Magneto-Mechanical Effects

The Signal Characteristics of Oil and Gas Pipeline Leakage Detection Based on Magneto-Mechanical Effects

Quantitative Study on MFL Signal of Pipeline Composite Defect Based on Improved Magnetic Charge Model

Investigation on the Formation Mechanism of Crack Indications and the Influences of Related Parameters in Magnetic Particle Inspection

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