Cause Analysis on Tube Bursting of High Temperature Superheater of Boiler in a Power Plant

The tube of high temperature superheater in a boiler of a 600 MW coal fired power plant had bursted for several times. The causes of tube bursting were analyzed by means of macro observation, chemical composition analysis, mechanical property test, metallographic examination, micro analysis and so on. The results show that the tube of high temperature superheater ran over temperature for a long time and oxide layer formed on the inner wall of the tube. The deposit of oxide layer at the elbow of the tube reduced the steam flow rate, so the temperature of the heating surface of the tube rose sharply. Transient overheating of the tube eventually resulted in the tube bursting.