Effect of an alkyl amine-based corrosion inhibitor for 1018 carbon steel pipeline in sea water

Purpose: The paper aims to report an experimental investigation of the effectiveness of an alkyl amine-based inhibitor on the corrosion behavior of 1018 carbon steel in sea water. The adsorption equilibrium for this corrosion inhibitor on carbon steel was also investigated. The corrosion inhibitor was evaluated based on parameters such as inhibitor concentration, temperature, stirring speed and pH. Design/methodology/approach: The experimental setup employed an autoclave with a flow circulation system. Weight loss determinations and electrochemical techniques such as polarization resistance and potentiodynamic polarization were used to detect and monitor the performance of the corrosion inhibitor. Surface examination of the steel substrate before and after applying different doses of inhibitor was undertaken using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS). Findings: Inhibition efficiency was enhanced by adsorption of amine-containing functional groups on the steel surface. This adsorption capacity was measured and fitted Langmuir and Shawabkeh-Tutunji isotherms and was found to require a maximum requirement of 1.08 mg of corrosion inhibitor to provide a monolayer of cover on the carbon steel surface. The inhibition efficiency increased with increasing the inhibitor concentration and solution pH. Moreover, increasing the solution temperature and stirring speed had an adverse effect on inhibition efficiency. Polarization data fitted by the Butler-Volmer Equation showed the values of anodic and cathodic Tafel coefficients were an average of 0.8 and 0.2, respectively. The measured corrosion rates decreased rapidly within the first hour after commencing the experiments, which is related to the formation of a protective oxide film. Research limitations/implications: More inhibitor concentrations can be studied in order to draw more comprehensive conclusions on the efficiency of the tested inhibitor. Practical implications: The effect of alkyl amine-based inhibitor on the corrosion inhibition characteristic of 1018 carbon steel (CS) in sea water was determined at different inhibitor concentrations, temperatures, stirring speeds and pH. Originality/value: The new information reported in this paper is the effect of alkyl amine-based inhibitor on the corrosion characteristics of 1018 carbon steel in seawater using an autoclave with a flow circulation system. The paper is valuable to researchers in the area of corrosion inhibitors and oil and gas industry.