Article Article
Analysis of Magnetic Flux Leakage Testing for Longitudinal Discontinuities in Sucker Rods

The detection of sucker rod discontinuities is an urgent, scientifically difficult problem to be solved in the oil industry. In this paper, the modeling and testing technologies for longitudinal discontinu-ities in sucker rods were studied using finite element analysis software. The magnetic flux leakage (MFL) testing simulation was carried out, and a double-coil direct current (DC) magnetization model was established. The simulation results showed that the magnetizing field is stable and close to a uniform magnetic field. The testing model for the longitudinal discontinuity was set up, and the axial MFL signals were extracted at different heights above the discontinuity. Meanwhile, the MFL data were analyzed and compared, and the effects of magnetization level and discontinuity size on the MFL testing were discussed for enhancing detection reliability. Finally, the peak of leakage magnetic field was obtained under different liftoff values, and the relation curve between the liftoff value and the peak of leakage magnetic field was achieved. In this way, the key data between the sensor and detection device could be measured. Study results indicate that the MFL double-coil magnetization approach can be used to detect longitudinal discontinuities in sucker rods.


Ahmad, M.I.M., A. Arifin, and S. Abdullah, 2015, “Fatigue Crack Effect on Magnetic Flux Leakage for A283 Grade C Steel,” Steel and Composite Struc-tures, Vol. 19, No. 6, pp. 1549–1560.

Benhaddad, S., and G. Lee, 2001, “Role of Microstructure in Sucker Rod String Failures in Oil Well Production,” Practical Failure Analysis, Vol. 1, No. 2, pp. 47–54.

Chen, J., S. Huang, and W. Zhao, 2014, “Three-Dimensional Defect Reconstruction from Magnetic Flux Leakage Signals in Pipeline Inspection Based on a Dynamic Taboo Search Procedure,” Insight: Non-Destructive Testing and Condition Monitoring, Vol. 56, No. 10, pp. 535–540.

Duan, D.L., Z. Geng, S. L. Jiang, and S. Li, 2014, “Failure Mechanism of Sucker Rod Coupling,” Engineering Failure Analysis, Vol. 36, No. 1, pp. 166–172.

Edens, C.W., 1997, “Electromagnetic Inspection: Wall Loss and Flaw Location in Oil Country Tubular Goods,” NDT & E International, Vol. 30, No. 1, p. 38.

Gotoh, Y., and N. Takahashi, 2004, “Proposal of Detecting Method of Plural Cracks and Their Depth by Alternating Flux Leakage Testing: 3-D Nonlinear Eddy Current Analysis and Experiment,” IEEE Transactions on Magnetics, Vol. 40, No. 2, pp. 655–658.

Hong, S.P., H.S. Cho, H.S. Lee, H.Y. Lee, and H.R. Cho, 1999, “Effect of the Magnetization Direction in Permanent Magnet on Motor Characteris-tics,” IEEE Transactions on Magnetics, Vol. 35, No. 3, pp. 1231–1234.

Katoh, M., N. Masumoto, and K. Nishio, 2003, “Modeling of the Yoke-Magnetization in MFL-Testing by Finite Elements,” NDT & E Inter-national, Vol. 36, No. 7, pp. 479–486.

Mandal, K., D. Dufour, T.W. Krause, and D.L. Atherton, 1997, “Investiga-tions of Magnetic Flux Leakage and Magnetic Barkhausen Noise Signals from Pipeline Steel,” Journal of Physics D: Applied Physics, Vol. 30, No. 6, pp. 962-973.

Roskosz, M., 2011, “Metal Magnetic Memory Testing of Welded Joints of Ferritic and Austenitic Steels,” NDT & E International, Vol. 44, Vol. 11, pp. 305–310.

Shengli Oilfield Highland Petroleum Equipment Co. Ltd., 2017, “Products, Sucker Rod,” accessed at on 15 June 2018.

Shi, Y., C. Zhang, R. Li, M.L. Cai, and G.W. Jia, 2015, “Theory and Appli-cation of Magnetic Flux Leakage Pipeline Detection,” Sensors (Basel), Vol. 15, No. 12, pp. 31036–31055.

Singh, S., W., B.P.C. Rao, S. Vaidyanathan, T. Jayakumar, and B. Raj, 2007, “Detection of Leakage Magnetic Flux from Near-Side and Far-Side Defects in Carbon Steel Plates Using a Giant Magneto-Resistive Sensor,” Measure-ment Science and Technology, Vol. 19, No. 1.

Sun, Y., and Y. Kang, 2010, “The Feasibility of MFL Inspection for Omni-Directional Defects Under a Unidirectional Magnetization,” International Journal of Applied Electromagnetics and Mechanics, Vol. 33, Nos. 3–4, pp. 919–925.

Tehranchi, M.M., M. Ranjbaran, and H. Eftekhari, 2011, “Double Core Giant Magneto-Impedance Sensors for the Inspection of Magnetic Flux Leakage from Metal Surface Cracks,” Sensors and Actuators A: Physical, Vol. 170, Nos. 1–2, pp. 55–61.

Xu, Z.H., X.M. Zha, and H.G. Chen, 2015, “A Simulation Study for Locating Defects in Tubes Using the Weak MFL Signal Based on the Multi-Channel Correlation Technique,” Insight: Non-Destructive Testing and Condition Monitoring, Vol. 57, No. 9, pp. 518–527.

Zhang, L., F. Belblidia, I. Cameron, J. Sienz, N. Pearson, and M. Boat, 2015, “Influence of Specimen Velocity on the Leakage Signal in Magnetic Flux Leakage Type Nondestructive Testing,” Journal of Nondestructive Eval-uation, Vol. 34, No. 2, pp. 1–8.

Zhang, Y., K. Sekine, and S. Watanabe, 1995, “Magnetic Leakage Field Due to Sub-Surface Defects in Ferromagnetic Specimens,” NDT & E Interna-tional, Vol. 28, No. 2, pp. 67–71.

Usage Shares
Total Views
218 Page Views
Total Shares
0 Tweets
0 PDF Downloads
0 Facebook Shares
Total Usage