Erosion-corrosion of Fe- and Ni-based tubes and coatings in a fluidized bed test rig during exposure to HCl- and SO2-containing atmospheres

Tubes made from five commercial alloys (Fe9Cr1Mo, 304L, Esshete 1250, 353 MA and Inconel 625) as well as two coating materials (Inconel 625 and Metco 8443) deposited on low alloyed steel tubes were exposed to different atmospheres in a laboratory fluidized bed test rig at 550 °C for 3 weeks (504 h). The atmospheres were air, air + 50 ppm HCl and air + 50 ppm SO2. Excluding the Metco 8443 coating, all materials show the lowest wastage rate in the SO2-containing atmosphere. For all exposure conditions, the best overall performance is shown by the Fe9Cr1Mo alloy. The circumferential wastage profiles recorded on tubes exposed in air and air + 50 ppm HCl show an erosion pattern with two maxima (Type A behaviour), while the tubes recorded in the SO2-containing atmosphere display only one maximum (Type B behaviour).