Abstract: Abstract:A tube crack accident of the boiler rear plate superheater in a power plant occurred. The macroscopic examination, the microstructure analysis and the thickness measurement of the oxide skin on internal wall were down for the cracked tube. Combining with the formation mechanism of the oxide skin, it was determined that the tube crack accident of the rear plate superheater is caused by overtemperature at long time and decreasing of the tube wall thickness. Based on the examination results of the rear plate superheater, the measures to ensure safe operation at long term were proposed.

Key words: Keywords:rear plate superheater, operate in overtemperature condition, decrease of thickness of tube wall, tube crackcaused leakage, safe operation