scholarly journals Defect Width Assessment Based on the Near-Field Magnetic Flux Leakage Method

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5424
Author(s):  
Erlong Li ◽  
Yiming Chen ◽  
Xiaotian Chen ◽  
Jianbo Wu
Keyword(s):  
Magnetic Flux ◽  
Near Field ◽  
Experimental Studies ◽  
Magnetic Flux Leakage ◽  
Geometrical Parameters ◽  
Destructive Testing ◽  
Lift Off ◽  
Two Peaks ◽  
Non Destructive ◽  
Flux Leakage

Magnetic flux leakage (MFL) testing has been widely used as a non-destructive testing method for various materials. However, it is difficult to separate the influences of the defect geometrical parameters such as depth, width, and length on the received leakage signals. In this paper, a “near-field” MFL method is proposed to quantify defect widths. Both the finite element modelling (FEM) and experimental studies are carried out to investigate the performance of the proposed method. It is found that that the distance between two peaks of the “near-field” MFL is strongly related to the defect width and lift-off value, whereas it is slightly affected by the defect depth. Based on this phenomenon, a defect width assessment relying on the “near-field” MFL method is proposed. Results show that relative judging errors are less than 5%. In addition, the analytical expression of the “near-field” MFL is also developed.

scholarly journals Magnetic Flux Leakage Course of Inner Defects and Its Detectable Depth

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Jianbo Wu ◽  
Wenqiang Wu ◽  
Erlong Li ◽  
Yihua Kang
Keyword(s):  
Magnetic Flux ◽  
Steel Structure ◽  
High Sensitivity ◽  
Magnetic Flux Leakage ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Near Surface ◽  
Testing Method ◽  
Non Destructive ◽  
Flux Leakage

AbstractAs a promising non-destructive testing (NDT) method, magnetic flux leakage (MFL) testing has been widely used for steel structure inspection. However, MFL testing still faces a great challenge to detect inner defects. Existing MFL course researches mainly focus on surface-breaking defects while that of inner defects is overlooked. In the paper, MFL course of inner defects is investigated by building magnetic circuit models, performing numerical simulations, and conducting MFL experiments. It is found that the near-surface wall has an enhancing effect on the MFL course due to higher permeability of steel than that of air. Further, a high-sensitivity MFL testing method consisting of Helmholtz coil magnetization and induction coil with a high permeability core is proposed to increase the detectable depth of inner defects. Experimental results show that inner defects with buried depth up to 80.0 mm can be detected, suggesting that the proposed MFL method has the potential to detect deeply-buried defects and has a promising future in the field of NDT.

Magnetic Flux Leakage Method of Railway Rails Defects diagnostics and its Place Among Mobile Means of Non-destructive Testing

2018 ◽  
pp. 105-119
Author(s):  
Nichoha, Vitalij ◽  
Shkliarskyi, Volodymyr ◽  
Storozh, Volodymyr ◽  
Matiieshyn, Yurij ◽  
Vashchyshyn, Liubomyr
Keyword(s):  
Magnetic Flux ◽  
Magnetic Flux Leakage ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Non Destructive ◽  
Flux Leakage

scholarly journals Inspection of Gas Pipelines Using Magnetic Flux Leakage Technology

2017 ◽  
Vol 17 (3) ◽  
pp. 37-45 ◽  
Author(s):  
Z. Usarek ◽  
K. Warnke
Keyword(s):  
Signal Processing ◽  
Magnetic Flux ◽  
Development Stage ◽  
Magnetic Flux Leakage ◽  
Destructive Testing ◽  
Oil Pipelines ◽  
Recorded Data ◽  
Pipeline Wall ◽  
Non Destructive ◽  
Flux Leakage

Abstract Magnetic non-destructive testing methods can be classified into the earliest methods developed for assessment of steel constructions. One of them is the magnetic flux leakage technology. A measurement of the magnetic flux leakage is quite commonly used for examination of large objects such as tanks and pipelines. Construction of a magnetic flux leakage tool is relatively simple, but a quantitative analysis of recorded data is a difficult task. Therefore, methods of magnetic flux leakage signal processing and analysis are still under development. A magnetic flux leakage in-line-inspection tool called FLUMAG 500 was constructed. FLUMAG 500 was designed for gas and oil pipelines inspection. In this paper principle of operation of FLUMAG 500 was described. Advanced algorithms of the signal processing and analysis was also developed. Results coming from the development stage as well as from the final construction of the tool were presented. Analysis of these results shows that FLUMAG 500 is a suitable tool for detection of corrosion defects in a pipeline wall.

scholarly journals Non-Destructive Testing of Steel Corrosion Fluctuation Parameters Based on Spontaneous Magnetic Flux Leakage and Its Relationship with Steel Bar Diameter

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4116 ◽  
Author(s):  
Qingyuan Zhao ◽  
Jianting Zhou ◽  
Qianwen Xia ◽  
Senhua Zhang ◽  
Hong Zhang
Keyword(s):  
Magnetic Flux ◽  
Steel Corrosion ◽  
Magnetic Flux Leakage ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Detection Technology ◽  
Steel Bar ◽  
Steel Bars ◽  
Non Destructive ◽  
Flux Leakage

In an actual structure, the arrangement of steel bars is complicated, there are many factors affecting the corrosion of steel bars, and these factors affect each other. However, accurately reflecting the corrosion of steel bars in actual engineering through theoretical calculations is difficult. Besides, it is impossible to detect and evaluate steel bars rust completely and accurately. This article is based on spontaneous magnetic leakage detection technology and adopts the method of stage corrosion and scanning along the reinforcing bar. Based on spontaneous magnetic flux leakage detection technology, the linear change rate of the tangential component curve of the magnetic flux leakage signal generated after the corrosion of a steel bar is studied, and a comparison is made between the steel bar coated concrete samples with different steel bar diameters. In this paper, the “origin of magnetic flux leakage signal” is defined as a reference point, which is convenient for effectively comparing the magnetic signal curves under all operating conditions. Besides, the “rust-magnetic fluctuation parameter” is proposed to accurately reflect the sudden change of leakage magnetic field caused by disconnection due to the corrosion of a steel bar. A new data processing method is provided for the non-destructive testing of steel corrosion using the spontaneous magnetic flux leakage effect, which can effectively reduce the influence of steel bar diameter on magnetic flux leakage signal and improve the precision of non-destructive testing technology of steel bar corrosion using the metal magnetic memory effect.

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