IMPROVED DIRECT TUBE REPAIR PROCESS

摘要

The wall of a pressure vessel tube having stress-corrosion cracks or the like is repaired by localized melting using laser welding, for fusing over defects by melting and re-solidifying the metal. A reactive cover gas is maintained over the area of localized melting in order to eliminate cracking caused by impurities in the tube material. The cover gas may be carbon dioxide or other gasses which act to scavenge the impurities. The wall of the tube may be melted twice in order to further improve the surface finish of the repair area; the first melt being to a depth of at least 80 % of the wall thickness, and the second melt being to a depth of about one-third the wall thickness.