By such tests as macroscopic inspection

metallographic analysis

scanning electron microscope(SEM)and X-ray diffraction(XRD)

the failure behavior of a seal flange made by TP304 stainless steel used at outlet of the urea hydrolysis equipment for flue gas denitrification was analyzed.The results show that

the failure of the flange plate was mainly caused by the continuous pitting corrosion and dissolved corrosion in high temperature and pressure urea corrosive medium.The interface between the corrosive medium and flange plate was serrated and the corrosion products were mainly Fe and Cr oxides.Loose structure and a large number of holes and cracks appeared in the corrosion products.The TP304 austenitic stainless steel is unsuitable for the seal flange material for urea hydrolysis equipment in flue gas denitrificaiton.