Abstract: An inspection robot is provided to traverse the interior of a pipeline for the purpose of checking the coating at the interior surface of the pipeline at the weld seams. The robot is designed to determine the thickness of the coatings and to provide a visual and recordable reading thereof. The robot is provided with a holiday detector in the form of a conductive brush mounted on a rotatable hub and adapted to sweep against the weld seam so as to locate any voids in the coating by means of electrical conductance, thus causing a holiday marker to activate and mark the pipeline interior surface so that the site can be revisited for repair.