This paper describes modern automatic overlay technology for applying weld overlay for surface protection of the waterwall and superheater/reheater tubes against corrosion or erosion/corrosion in utility coal-fired boilers. The discussion also includes the general characteristics and properties of modern weld overlays and the successfiil applications of the overlays to protect the lower furnace against sulfidation in boilers equipped with low NOx burners as well as boiler tubes against soot blower erosion/corrosion. Applications of weld overlay composite tubes for solving coal ash corrosion problems and
erosion/corrosion problems associated with superheaters and for solving carburization problems encountered in reheaters are also discussed.