Three failure analyses involving iron-nickel-chromium alloys (Alloy 800H and niobium modified HP-40) in high temperature steam service 1300°F to 1450°F (704°C to 788°C) arc presented. Boiler water carryover conditions led to steam-side salt deposits containing sodium, chlorine, and sulfur species. The unique conditions of extremely high temperatures and localized accumulation of aggressive salt species resulted in component failures that involved a molten salt attack mechanism not typically observed in steam-side environments.
Keywords: Alloy 800H, UNS No. NO8810, UNS No. N08811, Incoloy 800H, HP-40, HP-40Nb, niobium modified HP-40, molten salt attack, mixed molten salt attack, steam-side failures, iron-nickel-chromium alloys.