Weld Repair of Heat Recovery Steam Generator Tubing

摘要

This report describes two welding repair technologies that are being developed to address heat recovery steam generator (HRSG) tube failures. The first technology addresses tubing failures along the length of the tube. Damaged sections of the tube are severed from the existing tube, and a section is replaced via gas metal arc welding (GMAW) from the inside of the tube. A welding head specifically designed to perform this inside-out window-weld repair has been designed, assembled, and is now available to repair HRSG and boiler waterwall tubing. The second technology addresses tube-to-header attachment damage via removal of the existing stub tube from the inside of a header and then replacement of the tube with a slightly oversized and tapered stub tube. This repair and the equipment needed to perform the repair are complex in that the repair first requires cutting an access window into the header opposite of the stub tube, inserting the severing equipment, boring the stub tube, severing the stub tube-to-tube weld, replacing the stub tube, and rewelding using GMAW. This repair technology is currently under development and is scheduled to be available in late 2005.