| 摘要 |
A method for remotely removing and replacing defective tube ends of heat exchanger tubes located adjacent a tubesheet. In the method, a rotary cutting tool is inserted into each defective tube and the tube end portion is cut at a location near the tubesheet, a weld joint between the tube and tubesheet is removed, and the defective tube is then withdrawn through the tubesheet opening. Next, the resulting exposed end of the existing tube is remotely machined using a special rotary cutting tool, then a new replacement tube is inserted through the tubesheet opening and positioned in axial alignment and interfitting engagement with the end of the existing tube, after which the rear end of the new tube is expanded firmly against the tubesheet opening. The front or inner end of the replacement tube is then expanded firmly against the inner surface of the existing tube end, in preparation for welding these tubes together. Then, the new tube is welded to the existing tube and to the tubesheet to provide pressure-tight joints and complete the replacement tube installation. The special tools for tube cutting, tube positioning and tube expansion and their use is also described. |
