Reasons Analysis on Breaking off of a HRSG Header End Cover

Whole breaking off accident happened to a HRSG header end cover after 24 months operation. Means such as macroscopic analysis, chemical compositions analysis, hardness test, metallographic examination, scanning electronic microscope and energy spectrum analysis were used to analyze fracture reasons of the end cover. The results show that the failure type of the end cover was corrosion fatigue fracture. There was corrosive Cl- in the end cover medium which resulted in formation of cracks on inwall of the end cover under the action of stress and high temperature. The cracks propagated quickly under the action of thermal fatigue stress caused by temperature fluctuations, and finally led to breaking off of the end cover.