Crack Analysis of a Tower Inlet Line Flange in an EO/EG Unit
In a petrochemical enterprise's EO/EG unit,the inlet line flange of the glycol dehydration tower experienced fracture failure.In order to determine the cause of this failure,a series of characterizations were conducted,including macroscopic observation,hardness testing,chemical composition analysis,mechanical property analysis,metallographic examination,scanning electron microscopy(SEM),and energy dispersive spectroscopy(EDS).The results show that the flange crack in the EO/EG unit is due to chloride-induced stress corrosion fatigue.Specifically,the crack initiates at stress concentration sites such as machining marks,grinding indentations,and weld scars on the inner wall surface of the flange.Subsequently,it propagates outward under alternating loads and chloride stress corrosion cracking,eventually penetrating and causing leakage.Therefore,to ensure the safe operation of the flange,it is necessary to enhance manufacturing and installation quality control and to control the chloride ion content in the medium.
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