Experimental Study on Carbon Steel Corrosion and its Inhibition Using Sodium Benzoate Under Different Operating Conditions (original) (raw)
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The corrosion of carbon steel in single-phase (water with 0.1N NaCl) and two immiscible phases (kerosene–water) using turbulently agitated system was investigated. The experiments were carried out for Reynolds number (Re) range of 38 000 to 95 000 using circular disc turbine agitator at 40 • C. In two-phase system, test runs were carried out in aqueous phase (water) concentrations of 1% vol, 5% vol, 8% vol, and 16.4% vol mixed with kerosene at various Re. The effect of Re, percent of dispersed phase, dispersed droplet diameter, and number of droplets per unit volume on the corrosion rate were investigated and discussed. Test runs were carried out using two types of inhibitors: sodium nitrite of concentrations 20, 40, and 60 ppm and sodium hexapolyphosphate of concentrations 485, 970, and 1940 ppm in a solution containing 8% vol aqueous phase (water) mixed with kerosene (continuous phase) at 40 • C for the whole range of Re. It was found that increasing Re increased the corrosion rate and the presence of water enhanced the corrosion rate by increasing the solution electrical conductivity. For two-phase solution containing 8% vol and 16% vol of water, the corrosion rate was higher than single phase (100% vol water). The main parameters that play the major role in determining the corrosion rate in two phases were concentration of oxygen, solution electrical conductivity, and the interfacial area between the two phases (dispersed and continuous). Sodium nitrite and sodium hexapolyphosphate were found to be efficient inhibitors in two-phase solution for the investigated range of Re. On a ´ etudié la corrosion de l'acier au carbone dans des conditions monophasiques (eau avec 0,1N de NaCl) et diphasiques immiscibles (kérosène-eau) ` a l'aide d'un système agité turbulent. Les expériences ontété menées pour une gamme de nombre de Reynolds (Re) de 38000à 95000, avec un agitateur de type Rushtonà 40 • C. Des tests pour le système diphasique ontété effectuées dans des concentrations de phase aqueuse (eau) de 1%, 5%, 8% et 16,4% en volume, mélangéè a du kérosène pour différentes valeurs de Re. L'effet du nombre de Reynolds (Re), le pourcentage de la phase dispersée, le diamètre des gouttelettes dispersées et le nombre de gouttelettes par unité de volume sur le taux de corrosion a ´ etéétudié et analysé. Les essais ontété réalisés avec deux types d'inhibiteurs: du nitrite de sodiumà des concentrations de 20, 40 et 60 ppm et de l'hexapolyphosphate de sodiumà des concentrations de 485, 970 et 1940 ppm dans une solution contenant 8% en volume de phase aqueuse (eau) mélangéè a du kérosène (phase aqueuse) ` a 40 • C pour la gammecompì ete de Re. On a trouvé que l'augmentation du Re augmentait le taux de corrosion et que la présence d'eau améliorait le taux de corrosion en augmentant la conductivitéélectrique des solutions. Pour la solution diphasique contenant 8% et 16% en volume d'eau, le taux de corrosion est plus grand qu'en monophasique (100% en volume d'eau). Les principaux paramètres qui jouent un rôle majeur dans la détermination du taux de corrosion dans la solution diphasique sont la concentration d'oxygène, la conductivitéélectrique de la solution et l'aire interfaciale entre les deux phases (dispersée et continue). On a trouvé que le nitrite de sodium et l'hexapolyphosphaté etaient des inhibiteurs efficaces dans la solution diphasique pour la gamme de Ré etudié.
Corrosion of carbon steel in hydrochloric acid (HCl)–sodium sulphate (Na2SO4) solution mixture was investigated using rotating cylinder electrode (RCE) for a range of rotation velocity, 0–2000 rpm, solution temperature of 32–52 8C, and different oxygen concentrations. The corrosion rat was determined by using both weight loss method and electrochemical polarization technique. Different acid and salt concentrations were used ranged from 0.01 to 0.2 M for salt and 0.5 to 5% for acid. The conjoint effect of increased oxygen concentration and high rotational velocity was studied based on experimental measurements of O2 concentration. The effects of operating conditions on indole and cetyl trimethyl ammonium bromides (CTAB) inhibition efficiency were also studied and discussed. The results showed that increasing the rotational velocity leads to an increase in the corrosion rate depending on the concentration of salt and acid. Increasing the temperature and acid concentrations leads to an increase in the corrosion rate while the corrosion rate exhibited unstable trend with salt concentration leads to change of corrosion. It is found that increasing O2 concentration leads to a considerable increase in the corrosion rates especially at high rotational velocity. Indole and CTAB inhibitors exhibited very good inhibition efficiency in most conditions investigated with the former exhibited better inhibition efficiency arriving up to 87% at low rotational velocities. The inhibition efficiency of both inhibitors was found to decrease with increasing velocity. In addition, indole inhibitor reveals excellent inhibition efficiency even at high temperatures while CTAB efficiency decreased appreciably with temperature increase.
Study on corrosion rate of carbon steel pipe under turbulent flow conditions
The Canadian Journal of Chemical Engineering, 2010
ABSTRACT The effect of time (or corrosion products formation) on corrosion rate of carbon steel pipe in aerated 0.1 N NaCl solution under turbulent flow conditions was investigated. Tests were conducted using electrochemical polarisation technique by determining the limiting current density of oxygen reduction in Reynolds number (Re) range of 15 000 to 113 000 and temperature range of 30–60°C. The effect of corrosion products formation on the friction factor increase was studied and discussed. Empirical correlations for limiting current density as a function of Re were obtained at various solution temperatures for clean surface and for corroded surface. It was found that formation of corrosion products with time decreases the corrosion rate at low Re and temperature, while it increases the corrosion rate at high Re and temperature. As the corrosion products formed the surface roughness increased leading to increase the friction factor depending on temperature, Re, and corrosion rate.On a analysé l'effet du temps (ou la formation de produits de corrosion) sur la vitesse de corrosion d'un tuyau d'acier au carbone dans une solution 0.1 N NaCl aérée dans des conditions d'écoulement turbulent. Des essais ont été réalisés à l'aide de la technique de polarisation électrochimique en déterminant la densité de courant limité de la réduction de l'oxygène dans l'écart de nombres de Reynolds de 15000 à 113000 et dans l'échelle de température de 30°C à 60°C. L'effet de la formation de produits de corrosion sur l'augmentation du facteur de frottement a été étudié et discuté. Les corrélations empiriques pour la densité de courant limité comme fonction du nombre de Reynolds ont été obtenues à diverses températures de solution pour une surface propre et une surface corrodée. On a découvert que la formation de produits de corrosion avec le temps réduit la vitesse de corrosion à une température et un nombre de Reynolds bas tout en augmentant la vitesse de corrosion à une température et nombre de Reynolds élevés. Pendant que les produits de corrosion se formaient, la rugosité de la surface augmentait, ce qui a mené à une augmentation du facteur de frottement selon la température, le nombre de Reynolds et la vitesse de corrosion. © 2010 Canadian Society for Chemical Engineering
Monatshefte für Chemie/Chemical Monthly, 2009
The effect of sodium benzoate (SB) and sodium 4-(phenylamino)benzenesulfonate (SPABS) on the corrosion behavior of low carbon steel has been investigated using gravimetric method in the temperature range of 30-80°C, velocity range of 1.44-2.02 m s -1 and concentration range of 6.94 9 10 -4 to 4.16 9 10 -3 mol dm -3 SB and 3.69 9 10 -4 to 2.06 9 10 -3 mol dm -3 SPABS. Optimization of temperature, fluid velocity, and inhibitors concentration has been made. The obtained results indicate that the inhibition efficiency (w IE %) at 1.56 m s -1 is not in excess of 81.5% at 4.16 9 10 -3 mol dm -3 SB and 84.4% at 2.06 9 10 -3 mol dm -3 SPABS. The inhibitive performance of these compounds showed an improvement with increasing concentration up to critical values of SB and SPABS; beyond these concentrations no further effectiveness is observed. These inhibitors retard the anodic dissolution of low carbon steel by protective layer bonding on the metal surface. The adsorption of SB and SPABS on the low carbon steel surface was found to obey the Freundlich isotherm model. The FT-IR spectroscopy was used to analyze the surface adsorbed film.
Corrosion inhibition of carbon steel in oil and gas environments
Oil-based corrosion inhibitors have been evaluated for carbon steel in 3.5% NaCl and saturated CO2 gas. The corrosion rate for carbon steel was determined based on the electro-chemical method using linear resistance polarization (LPR). Specimens at various inhibitor concentrations were placed in a beaker connected to a CO2 cylinder for CO2 gas bubbling. The corrosion test was conducted at room temperature and high temperature (60 o C and 80 o C). Higher temperature conditions were used to study inhibitor stability. Results obtained from the LPR test indicated that the most effective corrosion inhibitor for carbon steel had between 5 to 100 ppm concentrations. The stability test showed that inhibitor efficiency was lower at higher temperature.
Corrosion Science, 2005
This work was carried out to study the inhibition mechanism of a carbon steel in a 200 mg l À1 NaCl solution by a non-toxic multi-component inhibitor used for water treatment in cooling circuits. The inhibitive formulation was composed of 50 mg l À1 fatty amines associated with 200 mg l À1 phosphonocarboxylic acid salts. Steady-state current-voltage curves, obtained with a rotating disc electrode, revealed that the properties of the protective layer were dependent on the electrode rotation rate and on the immersion time. The cathodic process of oxygen reduction was not modified in the presence of the inhibitive mixture. As expected, the current densities increased when the rotation rate was increased. In the anodic range, original behaviour was observed: the current densities decreased when the electrode rotation rate increased. The morphology and the chemical composition of the inhibitive layers allowed the electrochemical results to be explained. Two distinct surface areas were visualised on the metal surface and the ratio between the two zones was dependent on the flow conditions. This behaviour was attributed to a mechanical effect linked to centrifugal force. XPS analysis 0010-938X/$ -see front matter Ó (N. Pébère).
Inhibition of atmospheric corrosion of mild steel by sodium benzoate treatment
Journal of Materials Engineering and Performance, 2002
The objective of this study was to evaluate the effectiveness of sodium benzoate as an inhibitor to slow down or prevent atmospheric corrosion/discoloration of the local mild steel during storage in the Arabian Gulf region. Test specimens were prepared from locally produced reinforcing steel products. The inhibitor solution was applied on steel specimens at a concentration of 100 mM for 1 day at room temperature. Wooden exposure racks were used to hold as-received and inhibitor-treated specimens during atmospheric exposure for different periods. Corrosion was evaluated through weight loss determination and electrochemical technique. As expected, the Arabian Gulf atmosphere was corrosive on the as-received local mild steel. On the other hand, treatment of steel with sodium benzoate lowered its corrosion rate during initial days of its exposure to atmosphere. However, atmospheric corrosion inhibition performance of sodium benzoate deteriorated with exposure time after 30 or more days of atmospheric exposure, and the corrosion rates of sodium benzoate-treated specimens reached that of the unprotected specimens at the end of 90 days of atmospheric exposure.
Corrosion Science, 2017
The failure mechanisms of corrosion inhibitors in highly turbulent flow remain a disputed topic. In the present study, corrosion experiments of X65 pipeline steel were performed with an imidazoline-based corrosion inhibitor using a high-shear turbulent channel flow cell, which included a flow disturbance in the form of a small protrusion. Localized corrosion was observed at the protrusion that could be mitigated with an excess inhibitor concentration. It was found that wall shear stress (up to 5000 Pa) was not the cause of inhibitor failure. The flow acceleration at the leading edge of the protrusion caused a drop in pressure and led to cavitation, with bubble collapse further downstream. This was the main cause of inhibitor failure and localized corrosion. The observed behavior was interpreted in terms of corrosion inhibitor adsorption/desorption kinetics and the associated activation energy analysis.
Electrochimica Acta, 2002
Inhibition effects have been carried out on carbon steel in solutions containing different amines. These compounds were dissolved in some petroleum Á/water corrosive mixtures containing of acetic acid and NaCl. Corrosion inhibition afforded by ethylenediamine (EDA), hexylamine (HA), butylamine (BA), tert-butylamine (t-BA), propylamine (PA) and iso-propylamine (i-PA) has been studied by cyclic polarization (CP), electrochemical impedance spectroscopy (EIS) and optical micrography with a carbon steel rotating disk electrode at 25 8C. The best corrosion inhibition was obtained for the 4% of EDA, which is able to act as polarizing agent on the carbon steel surface. Thus, analysis of the change of inhibitor structure and its concentration in the solution allowed us to find the optimum parameters for obtaining the best inhibition. The observed difference in behavior of the additives can be attributed to the differing of solubility in various solvents ratio and to the differing of strict hindrance of the compounds to metal surface.
Journal of Materials Engineering and Performance, 2013
This study investigates the effect of two amine-based corrosion inhibitors in reducing the corrosion rate (CR) of 1018 carbon steel in formulated sea water. For discussion purposes, the two inhibitors are named Inhibitor A (belongs to the alkyl pyridine benzyl chloride quaternary family of inhibitors) and Inhibitor B (belongs to the alkyl amines family of inhibitors). The two inhibitors are routinely considered for applications by Saudi Aramco, the worldÕs largest oil producing and processing company, for reducing its corrosion problems in carbon steel pipelines carrying oil and gas. The experimental apparatus was a circulating flow loop system inside an autoclave. The experimental work was performed at pH 8.2, 55°C, and 1000 rpm. The inhibitors were evaluated at three different concentrations of 5, 10, and 15 ppm. The CR was determined using the weight loss method and electrochemical methods such potentiodynamic sweep and linear polarization resistance. The experimental results indicate that Inhibitor B reduced the CR more than that of Inhibitor A.