Patent ID: 6707296
Filing Date: 2004-03-16
Classification: G01N

Abstract:
A method of detecting cracks in an object of steel, such as a support plate of a bridge, which object is covered by a non-conductive layer of asphalt, concrete, or reinforced concrete, which layer has a thickness larger than 20 mm, using a probe comprising a transmitter system for inducing eddy currents in the object, and a receiver system for providing a signal indicative of the strength of a magnetic field or changes in the strength of a magnetic field, which method comprisesa) selecting a set of points of the object which are to be inspected; b) selecting a first inspection point from the set; c) positioning the probe at the selected inspection point, activating the transmitter system to induce eddy currents in the object; d) creating a record of the signal provided by the receiver system over a period of time; e) examining the record and comparing it to reference records, wherein the presence or absence of a crack can be inferred from the comparison; and f) selecting a next point of the set and repeating steps c) through e) until all points have had their turn.