MEASURING THE WALL THICKNESS OF AN ELECTRICALLY CONDUCTIVE OBJECT

摘要

Measuring the wall thickness of an electrically conductive object (2) using a probe (4) comprising a transmitter coil (6), a first receiver (8) and a seco nd receiver (10), which method comprises arranging the probe (4) near the objec t (2); inducing transient eddy currents in the object (2) and recording the signals of the receivers with time; measuring the wall thickness from a characteristic of one of the signals; calculating a characteristic value fro m a combination of the signals; and correcting the measured wall thickness for the distance between the probe (4) and the object (2) using a pre-determined relationship between the wall thickness and the characteristic value for different values of the distance between the probe (4) and the object (2).