Validation of a pulsed eddy current system for measuring wall thinning through insulation

Author(s):  
Colin R. Brett ◽  
Jan A. de Raad
2012 ◽  
Vol 17 (4) ◽  
pp. 298-301 ◽  
Author(s):  
Duck-Gun Park ◽  
C.S. Angani ◽  
M.B. Kishore ◽  
C.G. Kim ◽  
D.H. Lee

1997 ◽  
Vol 503 ◽  
Author(s):  
J. C. Moulder ◽  
J. A. Bieber

ABSTRACTPulsed, or transient eddy-current methods are an effective tool for quantitative characterization of hidden corrosion and cracking in multi-layer aircraft structures. Eddy currents are the method of choice for this task, since they penetrate multiple layers of metal, whether or not the layers are mechanically bonded. The pulsed eddy-current technique is an important advance over conventional eddy-current methods because it rapidly acquires data over a wide range of frequencies, thereby providing more information than a conventional, single-frequency eddy-current instrument. We have combined a pulsed eddy-current instrument with a portable two-axis scanner to produce an instrument capable of rapidly scanning aircraft lap splices in situ, producing pseudo-color images that reveal hidden corrosion or cracking. A unique feature of time-domain eddy-current data is the ability to selectively filter clutter from the image by time-gating the pulsed signal. Time-gating permits the user to select the inspection depth, thereby eliminating interference from upper layers, air gaps, lift-off variation and fasteners. By using a theoretical model of the pulsed eddy-current system, it is possible to interpret the data quantitatively, yielding quantitative maps of corrosion damage. Some of the same advantages of the pulsed eddycurrent technique apply to the characterization of hidden fatigue cracks as well, although the tieory for crack signals is less advanced.


2011 ◽  
Vol 301-303 ◽  
pp. 426-429
Author(s):  
Zhi Yuan Xu ◽  
Xin Jun Wu ◽  
Chen Huang ◽  
Yi Hua Kang

Pulsed eddy current (PEC) technique has been successfully used for measuring wall thinning of carbon steel equipments without removal of the insulation. In field applications, the probe performance decreases in presence of ferromagnetic claddings. This paper presents a method based on saturation magnetization to solve this problem. The main principle of this method is to weaken the magnetic shielding effect of the cladding by magnetizing it to saturation. A U-shaped magnetizer is designed to realize this method. Contrast experiments are performed on a Q235 steel plate covered by a galvanized steel cladding. The experiment results show that the thickness measurement range and lift-off range are increased by applying this method to the common PEC probe.


2013 ◽  
Vol 49 (5) ◽  
pp. 1653-1656 ◽  
Author(s):  
Shejuan Xie ◽  
Zhenmao Chen ◽  
Hong-En Chen ◽  
Xiaowei Wang ◽  
Toshiyuki Takagi ◽  
...  

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