Effect of Organic Acids in CO2 Corrosion (original) (raw)
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The effect of acetic acid on the CO2 corrosion of grade X70 steel
The effect of acetic acid (HAc) on the CO 2 corrosion of grade X70 steel was investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), polarization tests and electrochemical impedance spectroscopy (EIS). In the absence of acetic acid, a fairly dense layer of iron carbonate (FeCO 3 /siderite) was formed. At 500 ppm HAc, FeCO 3 layer became more porous. In addition, anodic/cathodic polarization curves were activated with the more pronounced effect on the cathodic side. By adding 1000 ppm HAc, similar polarization behavior was obtained and FeCO 3 layer became yet more porous than previous conditions. At 2000 ppm HAc, FeCO 3 layer disappeared completely, while polarization behavior changed and the limiting diffusive current density was observed in the cathodic side. There were two major increases in the corrosion rate at 500 and 2000 ppm HAc. The EIS results reflected similar behavior for the specimens exposed to the solutions with 0-1000 ppm HAc. Under these conditions, a charge transfer controlled behavior due to the FeCO 3 layer was observed which was accelerated by increasing HAc concentration. At 2000 ppm HAc, the corrosion behavior changed considerably and the formation/ adsorption of corrosion product followed by the dissolution process was observed.
Investigation of the Electrochemical Mechanisms for Acetic Acid Corrosion of Mild Steel
Corrosion, 2014
Acetic acid (CH3COOH) is recognized as an important factor in mild steel corrosion. Similar to carbonic acid (H2CO3) present in carbon dioxide (CO2)-saturated aqueous environments, acetic acid is a weak acid, which partially dissociates with the equilibrium being a function of pH and the solution temperature. Stronger than carbonic acid (pKa 4.76 vs. 6.35 at 25°C), acetic acid is the main source of hydrogen ions when the concentration of each acid is the same. Based on many different studies, it is agreed that acetic acid enhances the corrosion rate of mild steel by accelerating the rate of the cathodic (reduction) reaction. However, the electrochemical mechanism of acetic acid reduction at the metal surface is still being debated. One possibility is for the undissociated acetic acid to provide additional hydrogen ions by dissociation near the metal surface. In that case the main cathodic reduction is hydrogen ion reduction, and this mechanism is commonly referred to as a “buffering...
Chemical and Electrochemical Mechanisms behind Aqueous CO2 Corrosion of Mild Steel- a Basic Review
Sweet corrosion (CO2) is a major concern in internal corrosion of pipelines in oil industry. Dissolution of CO2 in water facilitates formation of a weak acid, H2CO3. Dissociation of carbonic acid provides proton and bicarbonate ions. Furthermore, bicarbonate’s dissociation leads to formation of carbonate and hydrogen ions. The thermodynamics and kinetics of such chemical reactions depends on temperature, solution pH, ionic strength, etc. Corrosion process has an electrochemical nature and it is widely agreed that presence of CO2 in aqueous environments increases corrosion rate of mild steel via accelerating cathodic reactions involved in the corrosion processes. Although mechanism of chemical reactions involved in CO2 corrosion is widely agreed, disagreement exists on the electrochemical part. This paper reviews the basics of chemical and electrochemical mechanisms in CO2 corrosion. With the emphasis on the “buffering behavior” and “direct reduction” mechanisms proposed for the presence of carbonic acid at the bulk solution and/or metal surface.
IOP Conference Series: Materials Science and Engineering
Models for predicting top-of-line corrosion (TLC) rates on carbon steels are important tools for cost-effectively designing and operating natural gas transportation pipelines. The work presented in this paper is aimed to investigate how the corrosion rates on carbon steel is affected by acids typically present in the transported pipeline fluids. This investigation may contribute to the development of improved models. In a series of experiments, the corrosion rate differences for pure CO2 (carbonic acid) corrosion and pure organic acid corrosion (acetic acid and formic acid) on X65 carbon steel were investigated at starting pH values; 4.5, 5.3, or 6.3. The experiments were conducted in deaerated low-salinity aqueous solutions at atmospheric pressure and temperature of 65 °C. The corrosion rates were evaluated from linear polarization resistance data as well as mass loss and released iron concentration. A correlation between lower pH values and increased corrosion rates was found for ...
Investigation of corrosion behaviour of iron in four different organic acids
Bayero Journal of Pure and Applied Sciences, 2019
INTRODUCTION Corrosion is defined as the destruction or deterioration of material because o with its environment which is often to metals but the corrosion engineers both metals and non-metals (Venkatachalam al., 2011). Corrosion attack infrastructures such as bridges, pipelines, vehicles, utilities (electrical, water, telecommunications, and nuclear power plant), engineering manufacturing, chemical industry, and the oil and gas industry (Ugi et al., 2017) the acids responsible for metal surface corrosion through acid attack mechanisms, resulting in millions of dollars being spent annually on maintenance. It is reported that, with proper corrosion prevention techniques, 25-30% of maintenance costs c (Isam et al., 2018). Corrosion of metal is an electro-chemical reaction between the metal and its environment in which the metal revert to iron oxide (Usman et al., 2015). chemical process causes a gradual alteration or wearing away of the metal surface and since the process returns the metal to its stable thermodynamic state, the action is considered as a degradation of the materia Zhang 2011). Corrosion of metal components has been recognized as a major problem i many engineering applications, due engineering systems such as brittle fracture and fatigue (Hurlen et al., 2013). Iron is known to be the best preferred materials for industry as it has many industrial applications easy availability, excellent physical properties, stronger and more workability, low cost, uncomplicated fabrication made it to use in different applications like pipeline materials in oil and gas industry water pipe lines al., 2008).The corrosive nature of acids also ABSTRACT The corrosion behaviour of iron in four different organic acid have been investigated using weight loss method. The acids used includes succinic, formic, maleic and citric acid. The results of the corrosion rates of iron in C 0.800 and 0.500 mg cm-2 h-1 respectively. The rate of corrosion increases with increasing concentration of acid and with increase in temperature. The study shows that the rate of corrosion follows the order of reactivity C
CO2 Top-of-Line-Corrosion; Assessing the Role of Acetic Acid on General and Pitting Corrosion
Corrosion
Based on a review of both literature and field data, it is apparent that the role of acetic acid (HAc) in oilfield brines is both extremely complex and somewhat controversial. Although it is commonly believed that the presence of this organic compound enhances both the general and the localized corrosion rate of carbon steel, HAc has recently been reported to also act as a weak general corrosion inhibitor in specific aqueous environments. These observations prompted a study into whether such behavior is apparent in a CO2 top-of-line corrosion (TLC) scenario, i.e., when HAc dissolves into condensed water that forms on the upper internal wall of carbon steel pipelines during wet-gas stratified flow. Four different water condensation rates/temperature TLC conditions were selected to investigate the role of HAc on both the kinetics and mechanism of carbon steel dissolution. A miniature three-electrode setup was developed to characterize the real-time TLC response through the implementat...
EVALUATE PERFORMANCE AND ANALYSIS CORROSION PRODUCTS FOR CARBON STEEL IN ACIDIC MEDIA
The performance of carbon steel (C1010) has been evaluated in three acidic solutions: 1M HCL, 1M H 2 SO 4 , 1M CH 3 COOH after immersion for 30 minutes and 300 minutes. The corrosion rate was determined by linear polarization resistance and potentiondynamic polarization techniques, and the corrosion rate in a short time of immersion was slightly higher than in a longer period of immersion d ue to deposits of the corrosion product on the sample surface slowing down the cathodic reaction rate and metal dissolution (anodic reaction), which can be clearly seen in PDP curves. In addition, X - ray photoelectron spectra was used to provide information on the actual compound present on the sample surface. Fe 2p, O 1s, Cl 2p, S 2p, C 1s core level spectra demonstrate that substrate termination does vary according to acidic solution type, with chloridic, sulfate, and acetate films being exhibited on top o f the surfaces of samples when immersed in 1M HCl, 1M CH 3 COOH , and 1M H 2 SO 4 respectively. The information provided by XPS supports and complements the data obtained from other techniques as mentioned above. All results indicate that the corrosion resistance of carbon steel in acetic acid is higher than hydrochloric acid or sulfuric acid due to the higher rate of hydrogen evolution in th e latter. In other words, the wo rsening of surface film stability in carbon steel occurs much faster in H 2 SO 4 than HCl or CH 3 COOH.
Journal of Petroleum Research and Studies, 2020
The presence of contaminants in water even in small amounts can cause considerablecorrosion damages of metals. This is due to free corrosion effect or the formation ofconcentration cell of pollutants resulting in a galvanic effect. The current work was devotedto study the effect of formic acid (CH2O2) as an organic pollutant on the corrosion rate ofcarbon steel under different operating conditions. It includes an investigation of galvaniccorrosion caused by the establishment of concentration cell of formic acid under differentoperating conditions. The ranges of operating parameters were formic acid concentration of10-4 - 10-5 M and temperature of 32 - 50 °C. The results showed that increasing formic acidconcentration to 10-4 M leads to an increase in the corrosion rate by up to 7.6 times that inthe water of 0.1N NaCl. In addition, the corrosion rate in each terminal in concentrationcell also increased by up to 2.3 times. Pumping of air in formic acid solution led to aconsiderable in...
Comparative Study and Analysis of Carbon Steel Corrosion in co2 Saturated Environment
African Journal of Engineering and Environment Research, Volume 2 of 1, January, 2021
Carbon steel is arguably one of the most efficient, reliable and safer kind of steel used in petroleum and gas industry for production, distribution and transmission of products. Acetic acid (HAc), is also one of the impurities in oil and gas during transportation from the well sites to the refineries. It is formed in the formation water, which also present in oil and gas production and transportation processes. Acetic acid aids corrosion in pipelines and as a result causes environmental degradation. It has been observed that high concentration of HAc increases the rate of corrosion of carbon steel in CO2 environment. Corrosion slows down production of oil and gas and thereby reduces revenue. In this work, a comparative study and analysis of carbon steel corrosion in the presence of HAc was carried out at 25 o C and 80 o C in CO2 saturated environment. Weight loss and surface analysis methods (XRD, EDX and SEM) were used to characterize the corrosion layers of the carbon steel samples at different conditions. The weight loss results show that the corrosion rate increased initially with the increase in the concentration of HAc and attained a maximum, and then gradually decreased. At 25 o C with 500ppm of HAc, the corrosion rate is 1.35 mm/yr, and 1.80 mm/yr when 1000ppm of HAc was added to the solution. At 80 o C and 500ppm HAc, the corrosion rate was 1.80 mm/yr and 2.70 mm/yr with 1000ppm of HAc. A further increase was observed at 3.45 mm/yr when 2500ppm of HAc was added to the system. This increase in corrosion rate is attributed to increase in temperature as increased temperature increases the rate of all reactions. The XRD analysis confirmed that the iron is formed in the absence of HAc while siderite (FeCO3), which is an ore of iron is observed on the materials with HAc. The SEM and EDX results confirmed that a fairly dense material of FeCO3 was formed in the absence of HAc and the layers became porous on addition of HAc to the solution.