Study on Low Frequency AC Excitation Magnetic Flux Leakage Testing for Defects With Different Depths

2018 ◽  
Author(s):  
Xinyuan Lu ◽  
Guanghai Li ◽  
Liangchao Chen ◽  
Yu Chang ◽  
Xiaozhu Zhang
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Low Frequency ◽  
Ferromagnetic Material ◽  
Magnetic Flux Leakage ◽  
Detection Depth ◽  
Ac Current ◽  
Different Depths ◽  
Ac Excitation ◽  
Flux Leakage

Magnetic flux leakage (MFL) method is a non-destructive method commonly used for equipment with ferromagnetic material. This paper presents a low frequency alternating current (AC) excitation MFL method. This method uses low frequency AC current excitation to obtain a high detection depth, and to realize the examination of internal and external surface of the ferromagnetic structures. Based on the low frequency AC excitation simulation model built in ANSYS Electronics18.1 software, the amplitude and phase parameters of magnetic field were extracted and calculated. With the changes of the defect depths in different positions of the steel plate, the results of amplitude and phase parameters of magnetic field were studied and analyzed. Then the experiments of detection on artificial defects with different depths in different positions were conducted. The simulation and experimental results were discussed.

ANSYS Simulation Technology of Pipeline Magnetic Flux Leakage Inspection

2013 ◽  
Vol 718-720 ◽  
pp. 1000-1005
Author(s):  
Li Jian Yang ◽  
Sen Lin Zhang ◽  
Song Wei Gao
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Electromagnetic Field ◽  
Magnetic Flux ◽  
Oil And Gas ◽  
Gas Pipeline ◽  
Magnetic Flux Leakage ◽  
Field Calculation ◽  
Inspection Method ◽  
Flux Leakage

In order to solve the need of the oil and gas pipeline defect quantification in the real-time online defecting, magnetic flux leakage inspection method was applied to oil and gas pipeline inspection. According to the basic theory of the electromagnetic field, finite element solution of electromagnetic field and ANSYS electromagnetic field calculation theory, using the function of ANSYS 's simulation and calculation for magnetic field, three-dimensional finite element model of the oil and gas pipeline defect was built up. Through simulating, the relationship between defect signal and defect size was found, the optimal distance of the hall sensor lift-off value was verified, the best magnetization of leakage magnetic field was discussed, and various factors to influence the magnetic flux leakage signal is analyzed.

The 3D Magnetic Field Analysis of Excitation Unit of Drill Pipe MFL Testing Based on ANSYS

2013 ◽  
Vol 694-697 ◽  
pp. 1179-1182
Author(s):  
Yi Lai Ma ◽  
Li Lin ◽  
Kai Wen Jiang ◽  
Xu Lin Zhao
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Drill Pipe ◽  
Magnetic Flux Leakage ◽  
Field Analysis ◽  
Ansys Software ◽  
Magnetic Field Analysis ◽  
The Cost ◽  
The Magnetic Field ◽  
Flux Leakage

Magnetic flux leakage is one type of electromagnetic nondestructive testing (NDT) which is widely utilized in the testing the integrity of drill pipe in the field. In this paper, the 3D model of excitation unit is completely built and analyzed by ANSYS software. The magnetic field of drill pipe in the combination of full excitation device is showed by ANSYS software instead of the physic experiments which increases the efficiency tremendously and decreases the cost and achieves the anticipated desire. It is considered that this technique can provide the theoretical basis of drill pipe excitation device and the magnetic flux leakage testing of drill pipe.

Finite Element Analysis and Research on Corrosion Defect of Tank Floor

2016 ◽  
Vol 853 ◽  
pp. 514-518
Author(s):  
Zhi Jun Yang ◽  
De Shu Chen ◽  
Liang Chen ◽  
Yu Zhuo Liu ◽  
Ran An ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Magnetic Flux ◽  
Magnetic Flux Leakage ◽  
Bottom Plate ◽  
Element Analysis ◽  
Corrosion Defect ◽  
Leakage Magnetic Field ◽  
Leakage Field ◽  
Flux Leakage

Storage tank is an essential vessel in petrochemical industry, and the corrosion of tank is an important reason for the safety hazard. The corrosion of tank bottom plate is more serious than the tank wall, and it is not easy to check and repair, when damaged to a certain extent it will cause the leakage of the media, then lead to waste of energy, environmental pollution, at the same time it will cause a major accident. Magnetic flux leakage testing is widely used in the field of tank floor inspection with the advantages of fast scanning speed, accurate results and so on. In this paper, the finite element simulation and analysis of the corrosion defect leakage magnetic field is used to obtain the data, and the characteristic of the leakage magnetic field is extracted. The effect of defect depth and width and shape on the magnetic flux leakage field is studied, and the distribution curve of the magnetic flux leakage field is obtained.

Finite Element Analysis of Magnetization Reversal Effect Based on Ferromagnetic Specimens

2014 ◽  
Vol 620 ◽  
pp. 127-132
Author(s):  
Xiao Wen Xi ◽  
Shang Kun Ren ◽  
Li Hua Yuan
Keyword(s):  
Magnetic Field ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Magnetic Flux ◽  
Magnetization Reversal ◽  
Tensile Load ◽  
Magnetic Flux Leakage ◽  
Element Analysis ◽  
The Magnetic Field ◽  
Flux Leakage

Using large finite element analysis (FEA) software ANSYS, the stress-magnetization effect on 20# steel specimens with different shape notches is simulated under the geomagnetic field and tensile load. With the stimulation, the magnetic flux leakage fields at certain positions of the surface specimen were measured. Through analysis the relationship between the magnetic flux leakage fields of certain points with tensile stress, the results showed that the magnetic field value at certain positions of specimen surface first decreases and then increases along with the increase of stress, which is called magnetization reversal phenomenon; Different gaps and different positions of the specimen show different magnetization reversal rules; By measuring the maximal variation of the magnetic field value △Hmax at certain positions of the surface specimen and by analyzing its change law, we can roughly estimate specimen stress size and distribution regularity of stress. Moreover, this article also discusses the effect of lifts-off of the probe on the law of stress magnetization.

The Design of a Mechanical Damage Inspection Tool Using Dual Field Magnetic Flux Leakage Technology

2005 ◽  
Vol 127 (3) ◽  
pp. 274-283 ◽  
Author(s):  
J. Bruce Nestleroth ◽  
Richard J. Davis
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
High Magnetic Field ◽  
Mechanical Damage ◽  
Magnetic Flux Leakage ◽  
Metal Loss ◽  
Unexpected Result ◽  
Lower Field ◽  
Study Results ◽  
Flux Leakage

This paper describes the design of a new magnetic flux leakage (MFL) inspection tool that performs an inline inspection to detect and characterize both metal loss and mechanical damage defects. An inspection tool that couples mechanical damage assessment as part of a routine corrosion inspection is expected to have considerably better prospects for application in the pipeline industry than a tool that complicates existing procedures. The design is based on study results that show it is feasible to detect and assess mechanical damage by applying a low magnetic field level in addition to the high magnetic field employed by most inspection tools. Nearly all commercially available MFL tools use high magnetic fields to detect and size metal loss such as corrosion. A lower field than is commonly applied for detecting metal loss is appropriate for detecting mechanical damage, such as the metallurgical changes caused by impacts from excavation equipment. The lower field is needed to counter the saturation effect of the high magnetic field, which masks and diminishes important components of the signal associated with mechanical damage. Finite element modeling was used in the design effort and the results have shown that a single magnetizer with three poles is the most effective design. Furthermore, it was found that for the three-pole system the high magnetization pole must be in the center, which was an unexpected result. The three-pole design has mechanical advantages, including a magnetic null in the backing bar, which enables installation of a pivot point for articulation of the tool through bends and restrictions. This design was prototyped and tested at Battelle’s Pipeline Simulation Facility (West Jefferson, OH). The signals were nearly identical to results acquired with a single magnetizer reconfigured between tests to attain the appropriate high and low field levels.

scholarly journals Magnetic Memory Inspection of an Overhead Crane Girder – Experimental Verification

2019 ◽  
Vol 26 (2) ◽  
pp. 69-76
Author(s):  
Agnieszka Kosoń-Schab ◽  
Jarosław Smoczek ◽  
Janusz Szpytko
Keyword(s):  
Stress Concentration ◽  
Magnetic Flux ◽  
Material Handling ◽  
Impact Load ◽  
Ferromagnetic Material ◽  
The Self ◽  
Magnetic Flux Leakage ◽  
Magnetic Memory ◽  
Earth Magnetic Field ◽  
Flux Leakage

Abstract The safety and efficiency of material handling systems involve periodical inspections and evaluation of transportation device technical conditions. That is particularly important in case of industrial cranes, since they are subjected to a large impact load and mechanical stresses acting on the crane's structure and equipment. The paper considers the possibility of a crane structure inspection using the metal magnetic memory (MMM) method. As an advanced non-destructive technique, this method can be employed for inspection of crane structure during operation, which leads to reduce the down time costs and increase the safety confidence in the monitoring process. The MMM technique is effective for early identification of the possible defect location and detecting the micro-damage in ferromagnetic structures through detecting the stress concentration areas. The basic principle of MMM method is the self-magnetic flux leakage signal that correlates with the degree of stress concentration. This method allows detecting early damage of ferromagnetic material through performing measurement in the earth magnetic field, without the use of a special magnetizing device. The paper presents the experimental results carried out on the double-girder overhead travelling crane with hoisting capacity 1000 kg. The influence of the load variation and duration time on the intensity of the self-magnetic flux leakage signal is analysed and discussed.

Testing of a Dual Field Magnetic Flux Leakage (MFL) Inspection Tool for Detecting and Characterizing Mechanical Damage Features

2008 ◽  
Author(s):  
Alex Rubinshteyn ◽  
Steffen Paeper ◽  
Bruce Nestleroth
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Residual Stresses ◽  
High Field ◽  
Mechanical Damage ◽  
Magnetic Flux Leakage ◽  
Low Field ◽  
Field Unit ◽  
Low Magnetic Field ◽  
Flux Leakage

Battelle has developed dual field magnetic flux leakage (MFL) technology for the detection and characterization of mechanical damage to pipelines. The basic principle involves the use of a high magnetic field between 140 and 180 Oersted (11.1 to 14.3 kA/m) and the use of a low magnetic field between 50 and 70 Oersted (4 to 5.6 kA/m). At high magnetic field levels, the flux leakage signal is primarily influenced by changes in the geometry of a pipe wall. At low magnetic field levels, the MFL signal is due to residual stresses and metallurgical changes as well as geometry changes to the pipe caused by mechanical damage and wall thinning. A decoupling signal processing method developed by Battelle is used to isolate the portion of the mechanical damage signals due to metallurgical damage and residual stresses, which allows the characteristics of a dent-gouge feature to be more clearly differentiated. The decoupling method involves first scaling down the high field signal to the level of the low field signal, and then subtracting it from the low field signal. This produces a decoupled signal that is primarily influenced by the residual stresses and metallurgical changes caused by mechanical damage. Rosen has developed a tool to test the dual field technology and is evaluating tool performance by running the tool in a 30 inch diameter pipeline segment. The tool itself is composed of three separate modules coupled together: a high field unit downstream of a low field unit which is downstream of a caliper arm unit that is used to detect and characterize reductions in the internal diameter. The general and magnetic design of the tool, along with the scaling algorithm is discussed. Results from a pull test in a pipe section with dents whose geometry has been independently characterized are also discussed. This work is partially funded by the U.S. Department of Transportation, Pipeline and Hazardous Materials Safety administration (DOT PHMSA) and the Pipeline Research Council International, Inc. (PRCI).

ANSYS Simulation Analysis of the Tri-Axial Pipeline Magnetic Flux Leakage In-Line Inspection

2012 ◽  
Vol 490-495 ◽  
pp. 2086-2090
Author(s):  
Li Jian Yang ◽  
Yan Xiu Su ◽  
Song Wei Gao
Keyword(s):  
Magnetic Field ◽  
Finite Element Method ◽  
Magnetic Flux ◽  
Simulation Analysis ◽  
Magnetic Flux Leakage ◽  
Ansys Simulation ◽  
Leakage Magnetic Field ◽  
Simulation Results ◽  
Flux Leakage ◽  
Three Components

In order to improve the detect performance of the traditional pipeline magnetic flux leakage(MFL) in-line inspection tools, the method of tri-axial pipeline MFL in-line inspection is advanced. By the three leakage magnetic field components: axial, radial and circumferential, the pipeline defects are recognized. Applying finite element method to build the simulation model of pipeline MFL in-line inspection, then proceeding 3-D simulation analysis. The three components of leakage magnetic field (axial, radial and circumferential) can be obtained by using ANSYS 3-D simulation, and the pipeline defects’ existence as well as the change of the defect’s size can be estimated by the three components’ graph. The simulation results indicate: By the ANSYS 3-D simulation, it proves that the tri-axial pipeline MFL in-line inspection can be achieved and the inspection can be used to improve the level of traditional pipeline MFL in-line inspection.

Nondestructive testing of turbine disk roots using solid-state GMR sensor arrays and an axial directional scanning system

2020 ◽  
Vol 64 (1-4) ◽  
pp. 525-531
Author(s):  
Juhyeon Park ◽  
Hoyong Lee ◽  
Gyejo Jung ◽  
Jinyi Lee
Keyword(s):  
Magnetic Field ◽  
Nondestructive Testing ◽  
Magnetic Flux ◽  
Permanent Magnets ◽  
Turbine Disk ◽  
Magnetic Sensors ◽  
Magnetic Flux Leakage ◽  
Scanning System ◽  
Sensor Probe ◽  
Flux Leakage

A nondestructive testing device, consisting of a scanner and signal processing circuits was developed to detect cracks in turbine disk roots. The scanner consists of a longitudinal feeder and a fir-tree-shaped sensor probe. The feeder inserted the sensor probe along the grooves of the turbine blade attachment. Meanwhile, permanent magnets were placed in opposite direction, to generate a closed magnetic field between the magnetic sensors located on the crests of the sensor probe. The fatigue crack in the turbine disk root occurred in the circumferential direction of the turbine. As a result, magnetic flux leakage was caused by disturbing the flow of closed magnetic field by permanent magnets. The magnetic flux leakage was measured by a magnetic sensor. The effectiveness of the proposed device has been verified using artificial defects introduced into the turbine disk roots by electric discharge machining.

DETECTION OF CRACKED POSITION DUE TO CYCLIC LOADING FOR FERROMAGNETIC MATERIALS BASED ON MAGNETIC MEMORY METHOD

2015 ◽  
Vol 75 (7) ◽  
Author(s):  
Azli Ariffin ◽  
Meor Iqram Meor Ahmad ◽  
Shahrum Abdullah ◽  
Wan Zulhelmi Wan Jusoh
Keyword(s):  
Stress Concentration ◽  
Magnetic Flux ◽  
Testing Machine ◽  
Ferromagnetic Material ◽  
Magnetic Flux Leakage ◽  
Magnetic Memory ◽  
Tensile Testing Machine ◽  
Potential Possibility ◽  
Crack Position ◽  
Flux Leakage

In this paper, metal magnetic memory (MMM) method is used to detect the micro-crack position on the ferromagnetic material due to the fatigue process by determining to the stress concentration zones in the metal surfaces. The MMM method was carried out on mild steel using Instron 8874 universal tensile testing machine with different values of the ultimate tensile strength (UTS) varies from 75%, 80% and 85% until the specimens fails. An equipment of stress concentration indicator was used to measure the magnetic flux leakage, Hp patterns in the specimens. The results indicated that the position of a crack on the specimen that failed due to fatigue test was correlated with the scanning interval from the magnetic flux leakage signals. Therefore, the MMM method provides the potential possibility to detect the position of fatigue damage or defect in the metal components.

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