High temperature corrosion of a thermowell in an incineration plant

The thermowell inside the post combustion chamber in an incineration plant failed due to severe high temperature oxidation. The failure was caused by deep intergranular oxidation attack and surface scaling of the component. The intergranular oxidation attack is more damaging to the material integrity. Inconel 600 was improperly used as the thermowell material due to insufficient Cr content for formation of a continuous protective Cr2O3 layer on the alloy surface, and the high operating temperature 950 °C nearly approaching its upper temperature limit (1000 °C). Replacement of Inconel 600 by more corrosion- and heat-resistant materials is strongly recommended.