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An improved method for the speedy and efficient repair of tubes contained in a furnace boiler waterwall involves milling an elongated slot at each end of a damaged tube section in a water wall, which section is thereafter cut away and replaced with a replacement tube section having elongated slots m

An improved method for the speedy and efficient repair of tubes contained in a furnace boiler waterwall involves milling an elongated slot at each end of a damaged tube section in a water wall, which section is thereafter cut away and replaced with a replacement tube section having elongated slots milled at each end which are cut to mate to existing tubes. The replacement tube section and existing tubes are aligned to form elongated slots through which interior welds are made to secure the replacement tube section. The elongated slots are then closed with covers cut from a second section of replacement tubing, and the water wall web is attached to the replacement tube section to complete the repair. Also disclosed are a milling machine used to mill the elongated slots, and drill and saw fixtures to aid in cutting away the damaged tube section. The improved method and apparatus enhance the precision and uniformity with which boiler tube repairs may be made, increase access to perform internal welds in boiler tubes and permit some prefabrication of necessary repair parts, thus reducing furnace down time for repair.

대표청구항 ▼

A method for repairing an existing tube contained in a boiler water wall, said boiler water wall having a plurality of tubes joined by web sections, said method comprising: (1) locating the first and second ends of a section of existing tube which is to be replaced in a boiler water wall; (2) perfor

A method for repairing an existing tube contained in a boiler water wall, said boiler water wall having a plurality of tubes joined by web sections, said method comprising: (1) locating the first and second ends of a section of existing tube which is to be replaced in a boiler water wall; (2) performing the following steps at each of said first and second ends: (a) locating and securing one or more studs on said boiler water wall; (b) mounting a milling machine on said studs; (c) driving said milling machine to mill an elongated slot in said section of existing tube; (d) removing said milling machine from said studs; (e) mounting a drill and a drill fixture to said studs; (f) drilling a hole through the web section of said boiler water wall, whereby said hole is adjacent said elongated slot; (g) removing said drill and fixture from said studs; (h) mounting a saw and a saw fixture on said studs; (i) inserting the blade of said saw into said hole and cutting said section of existing tube transversely, whereby said existing tube is cut generally along the midline of said elongated slot; and (j) removing said saw and said saw fixture from said studs; (3) cutting said web sections along the edge of said section of existing tube which is to be replaced; (4) removing said section of existing tube to be replaced; (5) beveling exposed ends of said existing tube remaining in said boiler water wall; (6) milling third and fourth elongated slots at a distance apart in a length of replacement tube; (7) cutting said replacement tube to fit the space inside said existing tube in said boiler water wall whereby said replacement tube is cut generally along the midline of said third and fourth elongated slots; (8) beveling the ends of said replacement tube; (9) aligning said third and fourth elongated slots remaining in said replacement tube with said elongated slots remaining in said first and second ends of saId existing tube in said boiler water wall; (10) welding said replacement tube to said existing tube in said boiler water wall at said first and second ends with watertight seals; (11) welding a separate cover over each of said aligned elongated slots with water tight seals; (12) welding said web sections along the length of said replacement tube to said replacement tube.