Rich text area. The CrMoV boiler tube was in operation during about 35,000 hours in a secondary superheater, exposed to gases at 900°C. During inspection, a thick scale was identified at the external surface and one sample was removed for analysis. The bainitic microstructure of the tube wall did not evidence strong high temperature degradation, but the external surface was carburized (under the scale), suggesting improper combustion conditions. The tested tube presented lower ductility than expected.