LAUSR

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.