Abstract: An extracting and replacing assembly for a heat exchanger or similar device. It comprises, on each end of the tubing of the heat exchanger, a vertical track mounted on each side of the heat exchanger, together with a vertical carriage movable on the track. A horizontal positioning track is carried by the vertical carriages, along which a horizontal positioning carriage is movable so as to be selectively positioned on the ends of any of the tubes of the heat exchanger. Such horizontal positioning carriage supports a tubing coil straightener and coil mount, a tube extraction system, a drive mechanism for severed tubes, a portable cutter for removing the sealed weld, a tube expansion roller, and/or automatic seal welder. Thus, tubing can be selectively removed and replaced in a minimum amount of time and at a minimum of expense in the confined and restrictive atmosphere that exists in may power generating plants.