Cause Analysis and Countermeasures on Bursting of T91 Steel Tubes in Supercritical Boiler Final Superheater

The bursting reason of T91 steel tube in supercritical boiler final superheater was analyzed. The results show that the steel tube bursting resulted from the thick oxide scale of inner wall peeled and deposited at the lower elbow of the tube, which caused the flow area in the tube decreasing and resulted in superheating. The number of bursting of T91 ferritic steel tubes caused by peel-off and accumulation of oxide scale could be decreased greatly or even avoided by measuring the oxide scale thickness and adopting corresponding measures according to the measure results.