DocumentCode :
1450753
Title :
Electromagnetic Inspection Method of Outer Side Defect on Small and Thick Steel Tube Using Both AC and DC Magnetic Fields
Author :
Gotoh, Yuji ; Sakurai, Kenta ; Takahashi, Norio
Author_Institution :
Dept. of Mech. & Energy Syst. Eng., Oita Univ., Oita, Japan
Volume :
45
Issue :
10
fYear :
2009
Firstpage :
4467
Lastpage :
4470
Abstract :
As thick steel tubes of small diameter are used in heat exchangers in various electric power plants and petrochemical plants, the inspection of these steel tubes is very important. The outer side defects are often observed on these small steel tubes. Moreover, since these steel tubes in heat exchangers are stored as a bundle, it is necessary to inspect the outer side defects of these steel tubes from the inside of the tube. In this paper, the electromagnetic inspection method using a direct current (dc) magnetic field and an alternating current (ac) magnetic field is proposed. The behavior of flux in steel is examined using 3-D finite-element method (FEM) taking account of hysteresis (minor loop) and eddy current. It is shown that the detection of outer side defect is possible by the differential permeability of minor loop of which the position on the hysteresis loop is affected by the existence of the defect.
Keywords :
eddy currents; finite element analysis; heat exchangers; inspection; magnetic hysteresis; magnetic permeability; nondestructive testing; pipes; 3-D finite-element method; AC magnetic fields; DC magnetic fields; FEM; alternating current magnetic field; differential permeability; direct current magnetic field; eddy current; electric power plants; electromagnetic inspection method; heat exchangers; hysteresis loop; outer side defects; petrochemical plants; thick steel tube; 3-D nonlinear finite-element method (FEM); Minor loop; nondestructive inspection; outer side defect on small steel tube;
fLanguage :
English
Journal_Title :
Magnetics, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9464
Type :
jour
DOI :
10.1109/TMAG.2009.2024894
Filename :
5257245
Link To Document :
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