Patent ID: 6051972
Filing Date: 2000-04-18
Classification: G01N

Abstract:
An apparatus for eddy current inspection of a metal tube having a thin layer on a radially outer outside face thereof with magnetic or electrical characteristics that are different from those of inner layers of said metal tube, said apparatus comprising:(a) a measurement head having a measurement coil for surrounding the tube; and(b) means for powering said coil with electrical voltage at a high frequency, greater than 100 kHz, and for analyzing an impedance of said coil;(c) wherein said head further contains magnet means surrounding said coil and magnetic flux guides (24) located on either side of said coil in an axial direction of said coil, co-operating with said magnet means and shaped to constitute a magnetic circuit that generates a magnetic field having a maximum intensity radially inside said coil and close to said coil.