Expandable eddy current probe for inspecting the interior of tubular conduits

Claim 1

A probe for longitudinally traversing the interior of an elongated, variable inner diameter installed steam generator tube, comprising: a central rod, opposing guide arms, each guide arm mounted on a pivot oriented transversely to the central rod at a fixed point intermediate the ends of the guide arm and each guide arm further including, a tube engaging guide arm free end configured to fit closely against a portion of the interior tube surface and an opposite guide arm lever end extending from the pivot point in a direction opposite the tube engaging end and terminating in a spaced apart relationship with the central rod; electrical sensor means disposed within the tube engaging free end, for detecting flaws in the tube wall currently adjacent the tube engaging end; compression means acting radially inwardly on the opposite guide arm lever end of each of the guide arms for urging the tube engaging free end of the opposing guide arms outward from the central rod into supportive contact with the interior of said tube; and means for selectively moving the probe longitudinally through said installed steam generator tube.