The performance of a commercially available oilfield corrosion inhibitor to control preferential weld corrosion in CO2-saturated brine was assessed. A submerged impinging jet (SIJ) was utilized to test carbon steel parent metal and a 1% Ni 0.25% Mo weld material at a temperature of 45°C. The dual nozzle arrangement of the jet allowed one parent metal and one weld material to be placed under each nozzle of the jet. The velocity over the parent metal was kept constant at 7 m/s whilst the weld material was subjected to velocities of 7, 8.8 and 11.4 m/s to simulate different severities of turbulence and shear stress. A pre-corrosion time of 2 hours was allowed before inhibitor was added to the system at a concentration of 100 ppm. The galvanic current between the parent metal and weld material was recorded by coupling the materials together. The galvanic current measurements were compared and reviewed for each case. The two materials were then assessed in their uncoupled state for each condition using AC impedance and linear polarization to help elucidate their behavior when coupled together.

Subject
Materials, Corrosion rate, Impingement, Flow velocity, Parent metals, Impedance, Preferential welds, Beads, Precorrosion, Corrosion inhibitors, Galvanic current, Mixed potential, Anodic inhibitors
Keywords:
inhibitor, galvanic current, flow-induced corrosion, submerged impinging jet, carbon dioxide, linear polarization, AC impedance
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2012
Association for Materials Protection and Performance (AMPP)
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