Title :
Validation of a coil impedance model for simultaneous measurement of electromagnetic properties and inner diameter of a conductive tube
Author :
Vasic, Darko ; Bilas, Vedran ; Ambrus, Davorin
Author_Institution :
Fac. of Electr. Eng. & Comput., Univ. of Zagreb, Croatia
Abstract :
In eddy-current nondestructive testing of conductive tubes such as oil-well casings, the measured tube wall thickness and inner diameter must be compensated for variations of electromagnetic properties of a tube material -magnetic permeability and electrical conductivity. Commercial systems for eddy-current nondestructive testing of oil-well casings incorporate multiple coils and multifrequency excitation for measurement of the inner diameter and the electromagnetic properties. This paper investigates the feasibility of the electromagnetic properties and inner diameter measurement with only one coil excited at one frequency. The authors have derived a coil impedance model and developed an inversion procedure for the determination of tube properties. Measurements have been performed on several tubes made of different materials. In order to validate the model and the optimization algorithm, measurement results were compared with the predictions of the model and finite-element analysis. Applicability of the method has been confirmed for the investigated frequency range (1-50 kHz).
Keywords :
coils; diameter measurement; eddy current testing; electric impedance measurement; electrical conductivity measurement; finite element analysis; magnetic permeability measurement; optimisation; 1 to 50 kHz; coil impedance model; conductive tube; eddy-current nondestructive testing; electrical conductivity; electromagnetic properties; finite-element analysis; inner diameter measurement; magnetic permeability; multifrequency excitation; oil-well casings; optimization algorithm; Coils; Conductivity measurement; Electric variables measurement; Electromagnetic measurements; Electromagnetic modeling; Frequency; Impedance measurement; Nondestructive testing; Permeability measurement; Predictive models; Coils; eddy currents; electrical conductivity; impedance modeling; inverse problems; magnetic permeability; modeling; tube inner diameter;
Journal_Title :
Instrumentation and Measurement, IEEE Transactions on
DOI :
10.1109/TIM.2005.861244