The protective properties of the oxide layer of TP347H high temperature superheater tube were analyzed in this study. The formation and exfoliation mechanism of the oxide layer was researched. The microstructure of the oxide layer of TP347H high temperature superheater tube was observed by scanning electron microscope(SEM) and the morphological features of it was also analyzed. The concentrations of alloy elements in the section of internal tube were quantitatively analyzed using energy dispersive system(EDS). The results showed that:The formation mechanism of oxide layer were

mainly steam oxidation mechanism and oxygen oxidation mechanism. When the pipe had enough content Cr

to ensure the normal internal and external diffusion conditions

and the Fe-Cr spinel was formed

even the protective layer of Cr

2

O

3

was formed. The oxide skin damage and exfoliation is mainly due to the oxygen oxidation mechanism. When the steam environment containing excess oxygen

dissolved oxygen as oxidant and it happened oxygen reaction with Fe-Cr spinel and Cr

2

O

3

chromium layer. That destroy the structure and composition of Fe-Cr spinel

Cr

2

O

3

chromium layer

so that the oxide layer loss of protective effect. The formation and exfoliation of oxide scale is mainly based on the mechanism of steam oxidation

the mechanism of oxygen oxidation and the mechanism of oxygen oxidation. The three mechanisms explain the whole process of the formation

growth and exfoliation of oxide skin.