Testing method and testing device for the detection of irregularities in the wall thickness of ferromagnetic pipes

摘要

The method involves passing an electrical current with several harmonic components through the pipe (22) under test, measuring the resulting magnetic field outside the pipe, measuring the current spectrum, detecting he magnetic field spectrum and deriving and evaluating the ratios of the identical spectral components of the current and magnetic field. AN Independent claim is also included for the following: a test arrangement for detecting non-uniformities in wall thickness of ferromagnetic pipes.