Flue gas desulfurization (FGD) units requre large components to accommodate the flow volumes and short contact times between raw gas and absorbent which are typical of these processes. For over two decades, increasing use has been made of nickel base alloys to protect flue gas ducts, absorbers, chimneys and internals against corrosion attack. In order to take advantage of their excellent corrosion resistance whilst keeping investment costs low, these NiCrMo-materials are frequently used in the form of a cladding applied in thin layers on the carbon steel structural load-bearing component. In view of the thin corrosion protection layer, the quality cjf the welded joint on the nickel alloy side assumes critical importance. This paper describes the development of tests and welding procedures for hot roll-clad plates used in large FGD components in a modern lignite-fired 3500 MW power pIant in Germany.
Keywords: Environmental technology, flue gas desulfurization (FGD), gas inlets, absorbers, nickel- chromium- molybdenum alloys, Alloy 59, UNS N06059, filler metal Alloy59,welding, hot roll-cladding, element mix-up