Abstract: A method of non-destructively testing a magnetisable conducting object surrounded by a magnetisable layer wherein the field strength of a primary magnetic field that is applied exterior to the magnetisable layer is abruptly changed. A vanishing secondary magnetic field generated by eddy currents induced by the changed field strength of the primary magnetic field is received and the temporal field strength of the received secondary magnetic field is analysed for deriving characteristics of the magnetisable conducting object. Furthermore, a transient tertiary magnetic field exterior to the magnetisable layer when the field strength of the primary magnetic field abruptly changes is applied wherein the orientation of the primary and tertiary magnetic field, respectively, are mutually opposite.

Abstract: The invention relates to a method of non-destructively testing a magnetisable conducting object surrounded by a magnetisable layer. The method comprises the step of abruptly changing a field strength of a primary magnetic field that is applied exterior to the magnetisable layer. Further, the method comprises the step of receiving a vanishing secondary magnetic field generated by eddy currents induced by the changed field strength of the primary magnetic field. The method also comprises the step of analyzing a temporal field strength of the received secondary magnetic field for deriving characteristics of the magnetisable conducting object. In addition, the method comprises the step of applying a transient tertiary magnetic field exterior to the magnetisable layer when the field strength of the primary magnetic field abruptly changes, wherein the orientation of the primary and tertiary magnetic field, respectively, are mutually opposite.

Abstract: Device for ultrasonic inspection of a wall of a pipeline that encloses a fluidum. The device is arranged to be moveable along a device axis through the pipeline along a longitudinal direction of the pipeline. The device is provided with electronic means, a body, a transmitting transducer and at least two receiving transducers, mutually spaced apart in a first transducer array along an array direction that is directed substantially parallel to the device axis. The electronic means are arranged to operate the transmitting transducer for transmitting a first ultrasonic signal to propagate through the fluidum to reach the wall, and to operate the at least two receiving transducers for receiving a second ultrasonic signal, which originates from the first ultrasonic signal after it is modified by the wall, according to a tandem method. The at least two receiving transducers are operated for receiving substantially simultaneously.