Elbow mainly controls medium flow direction in pipelines

and is one of the most commonly used pipeline components in oil and gas transportation. Corrosion-induced failure was studied on return pipeline elbow of regeneration tower in LPG desulfurization unit. From both macroscopic and microscopic viewpoint

distribution of corrosion pore diameters and reduction of wall thickness of failed elbow were surveyed. Physicochemical analysis was further performed by X-ray diffraction (XRD)and scanning electron microscope-energy dispersive spectrometer (SEM-EDS). The results show that corrosion is gradually intensified along fluid flow direction and a complete destruction zone is formed in the middle and outlet of the elbow. The main mechanism of elbow corrosion failure was that fluid scour destroyed protective film formed by electrochemical corrosion and weakened its protective effect on substrate

resulting in continuous corrosion of inner wall. Also

the presence of heat-stable salts aggravated elbow corrosion.