Interaction of inhibitors with corrosion scale formed on N80 steel in CO₂‐saturated NaCl solution

Abstract

The performance of the selected inhibitors, including thioglycolic acid (TGA), diethylenetriamine (DETA), and naphthene acid imidazolines (IM), on the bare surface of N80 steel and its scaled surface pre-corroded in CO 2 -saturated 1%NaCl solution was investigated by weight-loss method, electrochemical measurements using rotating cylinder electrode and surface analytical methods (SEM, XRD, and EPMA). The results indicate that there is a remarkable difference in inhibition efficiency of inhibitors on the N80 steel with and without precorrosion scale. The synergistic effect between inhibitors and corrosion scale not only depends on the size of inhibitor molecules, but also depends on the interaction of the inhibitor with the corrosion scale. It shows that IM and DETA have a good positive synergistic effect with the corrosion scale formed on N80 steel, although DETA has no inhibition efficiency for bare N80 steel, which can easily enter into the apertures of the corrosion scale, and block the active sites on the metal surface and the diffusion routeways of the reactant so as to depress the corrosion of the substrate metal. While TGA shows excellent inhibition efficiency on bare N80 steel, but it has an antagonistic effect with the corrosion scale although it has a small molecular weight as well as DETA, because TGA can dissolve corrosion scale and break its integrality and protectiveness performance.

Isoxazolidine derivatives as corrosion inhibitors for low carbon steel in HCl solution: experimental, theoretical and effect of KI studies

“…1-Bromotetradecane, hydroxylamine hydrochloride, triethylamine, silica gel 100, and paraformaldehyde (Fluka Chemie AG) and 1-tetradecene were used as received. Safrole (1) and eugenol (2) were purchased from Aldrich Co.…”

“…The white solid was crystallized from pet-ether to give the ditetradecylhydroxylamine 5 (3.5 g, 22.8%). The ltrate ($700 cm 3 ) was concentrated and the residual solid was crystallized from petroleum ether to give the white crystal of the tetradecylhydroxylamine 4 (9.5 g, 57.5% [1,3]dioxol-5-ylmethyl)-2tetradecylisoxazolidine (7). A mixture of hydroxylamine 4 (1.50, 6.5 mmol), paraformaldehyde (0.36 g, 12 mmol), and safrol (alkene) 1 (1.95 g, 12 mmol) in toluene (6 mL) was stirred using a magnetic stir bar at 110 C in an RB ask at 110 C under N 2 for 7 h. Aer removal of solvent, the residual mixture was chromatographed over silica gel using 5 : 1 hexane/ether as eluant to give adduct 7 as a white solid (2.2 g, 84%).…”

Corrosion behavior of carbon steel in chloride and bicarbonate ion‐enriched and CO2‐saturated solutions

“…Two peaks in C 1s spectra (Figure 5b) at 284.8 and 289.4 eV correspond to the adsorbed hydrocarbons and amorphous FeCO 3 , respectively. [27,28] The peaks in the Fe 2p spectra at 711.4 and 724.3 eV correspond to FeCO 3 , and the peak with a binding energy of 717.4 eV is associated with Fe 2 O 3 , [4,29] which originates from the oxidation of Fe 2+ after the specimens are taken out from the autoclave. By combining the XRD results, XPS patterns as well as results of previous literature, [6,30,31] it could be confirmed that both amorphous/crystalline FeCO 3 form at this condition and the matrix-like site is mainly amorphous FeCO 3 to a great degree.…”

“…[3] Field evidence indicated that CO 2 -induced sweet corrosion has caused more than 60% failures in equipment and facility with the attendant capital and operating expenditures. [4,5] Sodium bicarbonate (NaHCO 3 ) is served as a pH stabilizer proceeding to flow into the pipelines, where its concentration varies from small quantities to high levels, and its purpose is to restrict the general corrosion of pipelines within an acceptable range. [6,7] Several studies have focused on the role of bicarbonate ion (HCO 3 − ) in the corrosion of carbon steel exposed to CO 2 aqueous media [8][9][10][11][12][13][14] and provided an important contribution to the understanding of the corrosion mechanism.…”

The rotating cylinder electrode for studies of corrosion engineering and protection of metals—An illustrated review

“…3-amino-1, 2, 4, triazole was used as corrosion inhibitor for API X52 pipeline steel in CO 2 saturated brine solution using RCE [99]. Others [100], have evaluated thioglycolic acid (TGA), diethylenetriamine (DETA), and naphthene acid imidazolines as corrosion inhibitors of precorroded N80 steel in CO 2 -saturated 1% wt. NaCl solution using an RCE.…”