Inhibitor concentration on the corrosion behaviour of X70 steel in CO₂environments

Abstract

Purpose The purpose of this study is to investigate the corrosion behaviour of X70 steel in the presence and absence of various concentrations of inhibitor N-(2-o-Tolyl azophenyl)-acetamide (NTAA) in a CO2 environment. Design/methodology/approach The temperature was set at 80°C, and the flow velocity was 1.5 m/s. The inhibitor concentrations were 10, 20, 30, 60 and 80 ppm, and the CO2 partial pressure was 0.8 MPa. Weight loss method, pitting depth measurement, scanning electron microscopy and electrochemical techniques were used to investigate the inhibitory effects of the inhibitor NTAA. Findings The results showed that a small peak emerged in the curve of the corrosion rate versus inhibitor concentration plot at 20-30 ppm. Polarisation studies revealed that the anodic Tafel slopes changed greatly in the presence of an inhibitor; NTAA behaved as an anode-type inhibitor. At concentrations of 20-30 ppm, the incomplete coverage of the metal surface by inhibitor molecules resulted in macroscopic galvanic corrosion. Originality/value Corrosion behaviour of X70 steel in the presence and absence of various concentrations of an anode-type inhibitor was assessed. Cathodic Tafel slopes are almost unchanged, while the anodic Tafel slopes change significantly with the increase in inhibitor concentration. The corrosion rates of 20 and 30 ppm are almost three times of that of 10 ppm, which is because of the macroscopic galvanic corrosion caused by the inadequate coverage of inhibitor on steel surface.

A Review of Recent Advances in the Inhibition of Sweet Corrosion

“…Amines and amides are also among the types of compounds found to be effective CIs for steel in a CO 2 environment in a temperature range from 25–80 °C, [63,80b,c,93,108,135] as shown in Table S3 in Supplementary Material. Dodecylamine combined with iron‐oxidizing bacteria was employed to mitigate the corrosion of Q235 steel immersed for up to 21 days in CO 2 ‐containing artificial oilfield produced water [75]…”

“…The studies published in the last decade show that apart from the usual CO 2 ‐saturated NaCl solutions [93,108,135] or simulated oilfield water, [63,75] the steel samples tested were also immersed in other solutions. The corrosion of API X60 steel [80b] and API 5 A N80 steel [80c] in supercritical CO 2 and supercritical CO 2 ‐saturated aqueous phase with SO 2 , NO 2 , and O 2 , and in the presence of piperazine [80b] as well as of monoethanolamine, diethanolamine, and N ‐methyldiethanolamine [80c] was also investigated.…”

Recent progress of self-healing polyaniline organic composite coatings: active agents, methods and protection mechanism

“…Appropriate methods must be selected to minimize the impact on coatings' performance based on the characteristics of the various corrosion inhibitors. Additionally, to achieve optimal protection for metals, it is crucial to maintain a specific concentration of the corrosion inhibitors in the solution (Li et al, 2017;Zhang et al, 2015a;Shahnavaz et al, 2010). However, at this stage, the amount of corrosion inhibitor released from the coatings is not yet known, and the impact has not been thoroughly investigated.…”

“…Appropriate methods must be selected to minimize the impact on coatings’ performance based on the characteristics of the various corrosion inhibitors. Additionally, to achieve optimal protection for metals, it is crucial to maintain a specific concentration of the corrosion inhibitors in the solution (Li et al. , 2017; Zhang et al.…”