Kinetic Analysis of the X100 Steel Corrosion in Brine containing Inhibitor (Imidazoline) under different Turbulent Flow Conditions

Abstract

The accidents produced by the effects of corrosion on the pipeline steels used in the oil industry to transport the hydrocarbons and its derivatives, can be generating human and economic loss. This paper presents a study of the anodic and cathodic kinetics of an API X100 steel by the potentiodynamic polarization curves under turbulent flow conditions. The X100 steel was immersed in a NACE brine with 50 ppm of corrosion inhibitor dissolved under turbulent flow conditions at room temperature and atmospheric pressure of the Veracruz Port. In order to simulate the hydrodynamic conditions, a Rotating Cylinder Electrode (RCE) with different rotation speed was used. Electroactive species to be reduced were determined using the Eisenberg equation, as well as an analysis with dimensionless numbers was made to complement the study. Anodic kinetic analysis shown that the icorr was flow dependent and the values of anodic Tafel slopes were typical to activational or charge transfer corrosion process. On the other hand, the analysis of cathodic kinetics shown that the system under turbulent flow conditions is dominated by the oxygen diffusion (mass transfer process) from the bulk to metallic surface. According to the comparison of the experimental cathodic current and the theoretical limiting current attained by the Eisenberg equation, it can be established that the cathodic kinetics of the process is dominated by an oxygen reduction reaction.