Abstract:The failure causes of water wall tubes were analyzed by means of macro analysis, metallographic examination, scanning electron microscopy (SEM), energy spectrum analysis, and Xray diffraction (XRD). The results showed that the acid hydrogen corrosion occurred on the water wall tube. Longterm poor water quality and low pH were the main reasons for the corrosion thinning. Copper and its oxides in the corrosion product formed underdeposit corrosive environment, which accelerated the corrosion of water wall tube. Finally, the brittle tube burst occurred under the stress of the boiler medium.