Tool and method for rotopeening the peripheral tubes in a tubesheet

摘要

An improved apparatus and process for rotopeening metallic conduits of limited accessibility, such as the peripherally located heat exchange tubes around the tubesheet of a nuclear steam generator, is disclosed herein. The bowl-like inner wall which lies directly adjacent to such peripherally-located tubes renders it difficult to insert a rotopeening spindle into the open ends of these tubes in order to work-harden these tubes in the tubesheet region. Generally, the apparatus of the invention comprises at least one flexible rotopeening spindle, an advancing mechanism for remotely and incrementally advancing the flexible spindle through an open end of a selected peripheral tube, and a frame for supporting both the flexible spindle and the advancing mechanism. The length of the advancing mechanism is substantially shorter than the length of the flexible spindle so that the spindle and the advancing mechanism may be easily placed into a peening position with respect to the most remotely located tubes. The advancing mechanism includes first and second grippers which utilize expandable bladders for selectively gripping and ungripping the spindle. The first gripper is mounted on the wall-facing side of the frame, and the second gripper is reciprocably movable with respect to the first gripper. Additionally, the second gripper is rotatable and is mechanically linked to a drive means, in order to render it capable of rotating the rotopeening spindle once it is inserted into a selected tube end.