Pipeline Inspection Using Variable-Diameter Remote-Field Eddy Current Technology: 7,683,611

The present disclosure relates to a device and method for pipeline inspection, The inspection device may include an exciter coil capable of providing an alternating current magnetic field and producing eddy currents. A plurality of sensors may then be provided which are capable of sensing a magnetic field produced by the eddy currents and the sensors may be engaged with a sensor shoe. The sensors may then be capable of being positioned at a first distance D.sub.1 with respect to an inner pipe wall surface and capable of providing coupling to the magnetic field produced by the eddy currents. The sensor shoe may also be capable of retracting to a second distance D.sub.2, wherein D.sub.1<D.sub.2. The sensor shoe may be connected to a sensor support arm wherein the support arm may be pivotably attached to a fixed hub and to a control arm which control arm may then be pivotably attached to a driven hub.