Cracking reasons of deethanizer body steel plate in light hydrocarbon area

There was a cracking phenomenon in the deethanizer body steel plate of light hydrocarbon area in a terminal treatment plant of an oilfield. In order to find out the cracking reason of the plate, it was analyzed by physical and chemical test, finite element method and other methods. The results show that the chromium content in the chemical composition of the tower plate material was lower than the standard value, and its corrosion resistance was reduced. The cold bending treatment made the microstructure of the plate undergo martensite transformation again, and the hardness of the material increased. The surface layer of the material was subjected to bending tensile stress, and the internal low temperature medium increased the risk of material cracking. There were various loading stresses on the external surface of the tower and corrosion defects caused by sulfide and chloride ions, which caused stress corrosion cracking of the tower plate.