Laboratory Evaluation of Galvanic CO2 Corrosion and Inhibition of Carbon Steel Piping Partially Clad with Alloy 625

Abstract Some oil and gas production systems have critical components internally clad with corrosion resistant alloys for protecting against specific degradation mechanisms. Experimental and modeling studies have shown that uninhibited corrosion rates of carbon steel piping could nearly double in areas close to the CS-Alloy 625 interface. In this work, polarization, galvanic current and immersion tests were conducted to evaluate the effectiveness of inhibitors to mitigate galvanic corrosion and preferential weld corrosion of carbon steel coupled to Alloy 625 in CO2-saturated brine at 66 ˚C. Three inhibitors were evaluated for their ability to reduce galvanic corrosion at concentration of 150 ppm v/v. All of the inhibitors evaluated were shown to be efficient in mitigating uncoupled uniform corrosion, but only one was able to also reduce galvanic currents to negligible values while showing no evidence of preferential weld corrosion or pitting.