Failure Analysis of a Steel Elbow Pipe from a Gas Well

• Published in: Journal of failure analysis and prevention 2020-06, Vol.20 (3), p.723-733
• Main Authors: García-Martínez, María, Valles González, Mª Pilar, González Meije, Alejandro, Pastor Muro, Ana
• Format: Article
• Language: English
• Subjects: Cavitation; Characterization and Evaluation of Materials; Chemical analysis; Chemistry and Materials Science; Classical Mechanics; Corrosion; Corrosion and Coatings; Failure analysis; Gas wells; Hardness tests; Materials Science; Metal surfaces; Perforation; Pipe bends; Quality Control; Radiography; Reliability; Safety and Risk; Solid Mechanics; Structural steels; Technical Article > -Peer-Reviewed; Tribology; Water circulation
• ISSN: 1547-7029; 1728-5674; 1864-1245
• DOI: 10.1007/s11668-020-00870-5

A steel-type ASTM A234 WPB elbow pipe from a gas well, through which water pressurized at 4 kg/cm 2 and at 10–30 °C temperature was circulated, was perforated, originating a water leakage. Several tests were carried out in order to determine the cause of the perforation: Visual and radiographic inspection, chemical analysis, hardness test and microstructure, microscopy and fractographic studies. The presence of CO 2 in the water might be very important for the corrosion phenomenon in the welding area as a result of the presence of a galvanic couple between the weld bead and the pipeline steel. However, the CO 2 was not the only cause of the pipe damage. The fractographic study of the perforations and the flow analysis indicated that cavities have been originated as a consequence of a cavitation–corrosion phenomenon which is a particular erosion process caused by the implosion of gas bubbles on the metal surface.