Weld overlays extend life of parts in coal-fired boilers

摘要

The life of waterwalls and associated areas of coal-fired boilers can be extended considerably by protecting them with a stainless steel or nickel weld overlay, according to a paper presented by Richard Avery and Dennis W. Rahoi at the ASM Materials Solutions Conference in October. Titled "Stainless Steel an Nickel Alloy Weld Overlays in Coal-Fired Boilers," the paper discusses the factors that influence filler metal and overlay welding procedure selection. Some factors include corrosion resistance, thermal expansion coefficient, and thermal stability. The protection of steel waterwalls in coal-fired burners is becoming more urgent because low-NOx burners have changed the furnace atmosphere to a corrosive, sulfidizing atmosphere. Waterwalls that might previously have lasted 15 to 20 years may now need replacement in only four or five years. However, application of appropriate weld overlays may extend waterwall life to 20 years.