The corrosion behavior of carbon steels (L80 and C90) galvanically coupled to corrosion resistant alloys (13% Cr and 22% Cr) has been investigated in a Dynamic Field Tester (DFT) installed at a Gas / Condensate well head located near ANACO, Venezuela, which was producing an average of 270 NM3/min (13.8 MMSCF/D) of gas and 10 1/min (93 bbl/d) of liquid with 50 % water cut. The tests were run for two months at about 0.8 MPa (117 psi) CO2 partial pressure and 85°C. The effect of area ratio was studied at different superficial gas velocities (from 4 to 60 m/s).

Results showed that coupling carbon steel samples galvanically to CRA's tended to reduce both uniform and localized corrosion of the carbon steel. The anode/cathode area ratio affects the coupling behavior; and the position of the specimen, relative to the fluid flow, was found to have no significant effect.

The decrease in corrosion rates of galvanically coupled carbon steel specimens was related to differences in the composition and properties of the corrosion products, probably due to changes in the kinetics of nucleation and growth of iron carbonate films.

Subject
Materials, Corrosion resistant alloys, Corrosion rate, Flow velocity, Couplings, Corrosion products, Corrosion behavior, Fluids, Localized corrosion rates, Steel, Dry film thickness, Carbon steel, Risk reduction
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1995
Association for Materials Protection and Performance (AMPP)
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