Corrosion Failure Reason of a G105 Steel Drill Pipe

Severe localized corrosion occured on the surface of a G105 steel drill pipe with a diameter of 127 mm during the service process. Mechanical analysis, micro and macro morphology observation, EDS and XRD were employed to invesitgate the failure reason of the drill pipe. The results indicated that severe pitting occurred on the external surface of the G105 drill pipe and upset transition area; and several stripped pits were observed obviously on the surface of the drill pipe. The pitting of the G105 drill pipe was attributed to the oxygen corrosion and under-deposit corrosion induced by carbonate deposits, such as calcium carbonate. The chloride ions accelerated the localized corrosion of the drill pipe.