LIFE ASSESSMENT BASED ON OXIDES' DEPOSITION FOR AUSTENITIC STAINLESS STEEL TUBES USED IN ULTRA-SUPERCRITICAL UNITS

The structure,formation and flaking mechanism of oxide skin on austenitic steel have been presented,and the influence after flaking of oxide skin from austenitic steel boiler tube and resulting in blockage inside tube upon the temperature of tube-wall being studied,and the extent of blockage in tubes being classified according to the degree of blokage;1/8 blockage in the tube may be considered as clean tube;1/4 blockage in the tube is only in a small amount;3/8 blockage in the tube needing to be cut;1/2 blockage in the tube can be considered as deadly blocked.A tube life assessment model based on oxide film deposition has been put forward.