The first support (22) runs on the upper flange of the heat exchanger, allowing rotation about the vertical axis. A second support (24) moves along a radius of the first, and has the base of a vertical support (26) fixed to it. The rotary tool (30) is mounted at one end of the flexible shaft (32) which is turned at the other end by a motor (28). A hoist system (24, 36, 38) provides vertical motion for the shaft. Preferred features: The first support includes a channel section with rollers at one end, running around the flange (12). At the other end, two arms are fixed to the channel section, with rollers at their outer ends, again running around the flange. The channel section lies across the flange. The second support has a base plate supporting the hoist system with roller guides fitted to it and running in the channel section. The base plate can be held against movement. The second support moves relative to the first, between a position aligning the tool with the vertical axis of the heat exchanger, and another position aligning it with the heat exchanger tube most remote from the axis. A continuous belt (34) fixed to the motor moves it vertically. The belt is passed over a pulley mounted on top of the vertical support, and around others at the base. One of the pulleys is driven.
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