Inhibition of galvanic corrosion of carbon steel and nickel alloy in oil and gas production applications

Inconel-clad and carbon steel are being used in the construction of offshore risers from the sea floor to the platform. It is expected that only portions of the riser will be cladded due to the high cost of nickel alloy. The use of such clad materials introduces several possible corrosion and materials integrity concerns because of the possible galvanic corrosion between carbon steel (the anode) and the nickel alloy (the cathode). This work studies the inhibition of galvanic corrosion of carbon steel/Inconel 625 couple by inhibitors. The efficacy of several inhibitors was evaluated at conditions relevant to the riser applications. The best performed inhibitor was identified and its threshold concentration was investigated.