Characterization of the Corrosion Kinetic of X52 Steel in Seawater with Biocides

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Characterization of the Corrosion Kinetic of X52 Steel in Seawater with Biocides R. Galvan-Martinez1, R. Orozco-Cruz1, R. Torres-Sánchez2, E. A. Martínez-Martinez1 1

Unidad Anticorrosión, Instituto de Ingeniería, Universidad Veracruzana, Av. S.S. Juan Pablo II. S/N, Zona Universitaria., Frac. Costa Verde. C.P. 94294, Veracruz. México. Email: [email protected] 2

Universidad Michoacana de San Nicolás de Hidalgo, Instituto de Investigaciones Metalúrgicas, Edif. “U”, C.U. Apartado Postal 52-B, C.P. 58000, Morelia, Mich. México.

ABSTRACT Corrosion study of the API X52 pipeline steel immersed in seawater without biocide and with 0.25, 0.5 and 0.75 ppm of biocide, under static and dynamic (turbulent flow) conditions was carried out at room temperature and atmospheric pressure. The hydrodynamic conditions were controlled by a rotating cylinder electrode (RCE) and the rotation speed was 1000 RPM. I order to analyse the corrosion process, linear polarization resistance (LPR), and polarization curves (PC) were made. This work investigation shown that the corrosion rate is higher under turbulent flow conditions than static conditions. A localized corrosion attacks was found in the superficial analysis. INTRODUCTION The corrosion of the metallic structure under turbulent flow is complex, but this problem has been studied mainly in the oil industry [1-5], where, the flow and some gases (H2S and CO2) are very important in the behaviour of the phenomenon processes. The most common type of flow conditions found in industrial processes is turbulent flow; however, few corrosion studies in controlled turbulent flow conditions are available. With the increasing necessity to describe the corrosion of metals in turbulent flow conditions, some laboratory hydrodynamic systems have been used with different degrees of success [6]. The use of the rotating cylinder electrode (RCE), as a laboratory hydrodynamic test system, has been gaining popularity in corrosion studies under turbulent flow conditions [7-10]. This popularity is due to its characteristics such as, its operation mainly in turbulent flow conditions, its well-defined hydrodynamics, ease of assembly and disassembly and smaller volume of fluid used [11-13]. One method for corrosion protection is the use of inhibitors [14,15] which influence the rate of the process. Inhibitor studies cover a spectrum of activities, ranging from protection mechanisms through the search of new compounds and the appraisal of competitive commercial products to the monitoring of industrial systems in which inhibitors are being used [16]. The inhibitors like biocides can modify the dissolution rate of metals, influencing the kinetics of the electrochemical reactions which constitute the corrosion process. The aim of this work was to analyses the corrosion behaviour of the pipeline steel immersed in seawater with different biocide concentrations at static and dynamic condition using the electrochemical corrosion techniques.

EXPERIMENTAL PROCEDURE Test environment. All tests were carried out at room temper