Abstract

ESCALANTE, Mariana; OCHOA, Nathalie; SEQUERA, Carlos  and  JASPE, Jaysmlen. EVALUATION OF THE CO2 CORROSION RESISTANCE OF NEW LOW CHROMIUN STEELS USING FOR WELLS TUBING BY ELECTROCHEMICAL TECHNIQUES. Rev. LatinAm. Metal. Mater. [online]. 2014, vol.34, n.1, pp.76-85. ISSN 0255-6952.

The present work was carried out to evaluate the CO2 corrosion resistance of carbon steels used for tubing in oil and gas industries. Two low alloy steels containing 3% Cr, identified as 3CrA and 3CrB, were studied by electrochemical techniques (Chronopotentiometry, Voltamperometry, Electrochemical Impedance Spectroscopy and Linear Polarisation Resistance) coupled with a rotating disk electrode in order to control the hydrodynamic conditions of the system. Results obtained for 3% Cr steels were compared with those obtained for the conventional carbon steel, obtained from a N80 grade pipe, to evaluate the advantages of these new materials in terms of their CO2 corrosion resistance. Electrochemical tests were performed in a 3.5% NaCl solution previously deaereated and saturated with CO2 at 80 °C up to 72 h of immersion at 1000 rpm. Electrochemical measurements revealed that the corrosion resistance of low Cr steels is higher than that obtained for the carbon steel and decrease in the following order: 3CrB > 3CrA > N80. It is thought that these results might be explained by the differences found in the metallurgical characteristics of the steels (chemical composition and microstructure). In addition, it was found that the CO2 corrosion resistances of the steels increase with the immersion time, regardless of their chemical composition. This behavior was attributed to the formation of a corrosion product layer on the metal surface when the immersion time increases, mainly blocking the metal dissolution reaction.

Keywords : CO2 Corrosion; Low Alloy Steels; Electrochemical Measurements; Production Tubing..

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