Patent ID: 7514918

Claim:
A method for monitoring wall thickness of an object having an electrically conductive wall, using a pulsed eddy current probe comprising a transmitter means and a receiver means, by inspecting the same location on the wall repeatedly over an extended period of time, which method comprises: selecting an inspection location on the wall; at a plurality of inspection times θ m (m=2, . . . , M), arranging the probe in a predetermined position relative to the selected inspection location, inducing transient eddy currents in the object by activating the transmitter means, recording signals V m with the receiver means; determining, for each inspection time θ m , a temperature T m indicative of the temperature of the object at the inspection location; and determining, from each of the signals V m , a wall thickness d m pertaining to inspection time θ m , wherein the temperature T m is taken into accounts; wherein each signal V m is recorded as a function of time t and exhibits a characteristic change at a characteristic time τ m , wherein the step of determining a wall thickness d m comprises determining from the signal V m a characteristic value Φ m which is a measure of the characteristic time τ m , and determining the wall thickness d m from the characteristic value Φ m , wherein use is made of a first predetermined relationship between the characteristic value and the wall thickness, for the event that the temperature is constant, and a second predetermined relationship between the characteristic value and the temperature, for the event that the wall thickness is constant.