Cracking Reason Analysis of Ethylene Oxide Evaporator

The cracking reason of ethylene oxide evaporator in one petrochemical company was studied by means of metallographic examination, fracture analysis of the failure samples, energy spectrum analysis of the corrosion product and so on. The results showed that the microstructure near the welding heat affected zone was sensitized due to the welding process, which led to the precipitation of chromium carbide along grain boundary and the lack of Cr precipitation near grain boundary. Furthermore, under the combined action of the stress and corrosive medium, the intergranular stress corrosion cracking took place in welding heat affected zone of the ethylene oxide evaporator.