Juan Mendoza-Flores

Electrochemical Behavior of API X70 Steel in Hydrogen Sulfide-Containing Solutions

As an attempt to contribute to the understanding of the cor- rosion process of steel by hydrogen sulfi de (H2S), the corro- sion behavior of an X70 pipeline steel immersed in several H2S-containing solutions is analyzed in this work. Linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) techniques were used in order to charac- terize the corrosion behavior of X70 steel in H2S-containing solutions. Electrochemical parameters such as charge-transfer resistance, Rct, polarization resistance, Rp, and corrosion rate are presented in this work. Additionally, a comparison be- tween static and turbulent fl ow conditions was made in order to describe the corrosion behavior of X70 steel. Turbulent fl ow conditions were controlled using the rotating cylinder electrode (RCE) (at 1,000 rpm) in a saturated H2S solution.

Electrochemical Noise Study on Corrosion of Low Carbon Pipeline Steel in Sour Solutions

Electrochemical Noise (EN) measurements for low carbon pipeline steel (X52) samples were carried out in 3.5% NaCl aqueous and NACE solutions. Both testing solutions were saturated with hydrogen sulphide (H2S) at 20 and 60 oC, under static conditions. EN data was analysed in the time domain. Parameter such as Electrochemical Noise Resistance (Rn) and Localization Index (LI) were determined from the analysis in the time domain. Also, Rn results are compared with traditional Linear Polarization Resistance (LPR) data. A superficial analysis was carried out by a scanning electron microscopy (SEM) with Energy Dispersive X-Ray analyses (EDX). A good correlation was observed among the used techniques and relevant electrochemical data related to the corrosion phenomena was obtained. According to Rn, the corrosion rate (CR) values of the steel sample immersed in 3.5% NaCl are higher than the CR of the steel samples immersed in NACE solution. The morphology of the corrosion process obtained by SEM was a localized type and this behaviour was corroborated by the results obtained by LI where these LI values are 1 or close to 1.