Nondestructive electromagnetic inspection of pipelines incorporated in an electrically closed loop

摘要

The method according to the invention comprises producing an alternating magnetic flux coupled to an electrically closed loop which includes a pipeline to be checked, and measuring at least on electromagnetic field parameter over the whole length and perimeter of the pipeline. The distribution function of the electromagnetic field parameter thus obtained is indicative of the state of the pipeline. The method is more effective than the conventional techniques in that it ensures a more uniform spreading of current over the pipeline, in that it makes possible to inspect hard-to-get-at portions of pipelines without installing magnetic flux excitation means at those portions, and in that it rules out the effects of the magnetic flux on the output signals of measuring transducers. The invention is further concerned with a device for nondestructive inspection of pipelines primarily, pipelines, of atomic power stations. The device according to the invention comprises one or more closed magnetic circuits, each intended to accommodate a portion of a pipeline or portions of a number of pipelines for checking purposes. Portions of the magnetic circuits are encompassed by exciting coils. The device further incorporates an a.c. source, a system of inductance coils, a system of magnetic field measuring transducers, a communication link, a unit for processing signals arriving from the magnetic field measuring transducers, and a data presentation unit.