Corrosion Behavior of API-X120 Carbon Steel Alloy in a GTL F-T Process Water Environment at Low COD Concentration (original) (raw)
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Corrosion, 2013
The corrosion behavior of API 5L-X65 carbon steel in a carbon dioxide (CO 2)-saturated solution was investigated by electrochemical measurements (polarization curves, Levich plots, and electrochemical impedance spectroscopy) with a rotating disk electrode. Different experimental conditions such as hydrodynamics, immersion time, and temperature were considered. From the polarization curves, it was shown that both the anodic and cathodic current densities decreased as the electrode rotation speed, the immersion time, and the temperature increased. This behavior was in agreement with the impedance results obtained at the corrosion potential. It was shown that the corrosion processes were initially controlled by mass transport but they became under activation control for longer immersion times. Scanning electron microscopy was used to characterize the corrosion products. For short immersion times (2 h and 6 h), the corrosion products mainly deposited on the cathodic sites (pearlitic zones) of the carbon steel surface forming a heterogeneous layer, whereas they covered the whole electrode surface after longer periods (>15 h). At a microscale, localized corrosion, as a result of galvanic coupling between pearlite and ferrite, was also observed.
Materials Research, 2013
X52 and X60 high strength low alloy (HSLA) steels are widely used in the construction of petroleum pipelines. This paper discusses the corrosion resistance of X52 and X60 steels in CO 2 containing saltwater at pH 4.4 and 50 °C. A circulating flow loop system inside an autoclave was used for conducting the experimental work. The rotating impeller speed was 2000 rpm. The corrosion rate was monitored using in situ electrochemical methods such as potentiodynamic sweep, linear polarization resistance, and electrochemical impedance spectroscopy (EIS) methods. Results indicated that the corrosion rate of X60 steel is relatively higher than that of X52 steel.
International Journal of Electrochemical Science, 2017
Surface analyses aimed at assessing the corrosion damage suffered by API 5L X52 steel as a result of long immersion times in an aqueous salty medium (ASM), in absence and presence of oxygen, were carried out. The ASM chemical analyses revealed high concentrations of inorganic and organic ions, which evidenced a highly corrosive medium. The characterization of the corrosion products formed after 60 days exposing the steel sample to the ASM was performed by X-ray photoelectron spectroscopy (XPS), which confirmed the presence of different iron oxide faces. The modeling of electrochemical impedance spectroscopy (EIS) spectra showed that the electric charge transfer is a function of the temperature and immersion time used to expose the steel sample to the aqueous medium. Finally, the SEM/EDX analyses confirmed the combined presence of a not-compact film with corrosion products and salts on the surface, having as a result, an irregular and porous surface topography.
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 Science and Engineering, 2019
Oil and gas industry is constantly facing challenges in prospecting and transport, dealing with the corrosion and degradation of the pipelines. This work presents an electrochemical evaluation of API X65 steel exposed to CO 2 /thiosulfate (10-3 mol/l) aqueous deaerated medium. Sweet and sour corrosion were studied simultaneously. Electrochemical Impedance Spectroscopy (EIS) and Linear Polarization Resistance (LPR) tests were performed using an autoclave, 5 bar of CO 2 partial pressure at 25, 90 and 120 °C with and without H 2 S. Corrosion products were characterized by Weight loss, Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). Protective corrosion conditions were achieved at 120 °C with and without H 2 S. Without H 2 S, a stable and denser FeCO 3 film was formed. With H 2 S, FeS film reduced the CO 2 corrosive effect and retarded FeCO 3 precipitation. Both cases demonstrated an improvement of the substrate corrosion resistance at 120°C. At this temperature occurred a competitive films formation, reflecting in a corrosion rate decrease.
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.
Corrosion, 2007
Corrosion of carbon steel in un-buffered NaCl solutions was studied applying linear potential sweep technique to a rotating disk electrode. Current-potential curves were obtained from linear potential sweep at a rate of 1 mV s À1 in solution with concentrations in the range 0.02-1 M NaCl and rotation rates in the range 170-370 rad s À1 , at 22°C. Potential sweeps, which were conducted in the potential range À700 to À100 mV/SHE, were started from the cathodic limit in order to approach the measurement of corrosion under rust-free conditions. Polarization curves were analyzed with a superimposition model developed ad hoc and implemented in a computer program, which enabled determining the corrosion rate and kinetics parameters of the underlying anodic and cathodic sub-processes. The anodic sub-process, dissolution of iron, was well described in terms of a pure charge transfer controlled reaction, while the cathodic sub-process, oxygen reduction on iron, was well described in terms of mixed mass transfer and charge transfer control. Increase of electrode rotation rate increases the limiting current of oxygen reduction, which results in an enhanced corrosion rate of carbon steel. Increase of NaCl concentration has a dual effect: the limiting current of oxygen reduction decreases as a result of the influence of NaCl concentration on solution viscosity and the anodic dissolution of iron increases due to the influence of NaCl on pitting formation. However, this last mechanism predominates and a net increase in carbon steel corrosion rate is observed in this case.
Corrosion Of Carbon Steel In Waters Of Varying Purity And Velocity
NACE - International Corrosion Conference Series
There have been several instances where water purified from seawater by reverse osmosis has caused accelerated corrosion of carbon steel pipes. Therefore research was undertaken to determine the corrosion rate of low carbon steel in water with different contaminants, with and without aeration, and at different velocities. The results show that in high purity deionized (DI) water with oxygen, the corrosion rates were initially very high but dropped rapidly within a few hours to <100µm/yr. In jet impingement of DI water with oxygen, the corrosion rates dropped even lower, approaching zero, because the steel surface passivated. Water analysis from the reverse osmosis units from the offshore oil drilling platforms showed that reverse osmosis units would typically leave behind many ppm of NaCl and Na 2 SO 4 . Therefore laboratory tests were conducted and it was found that adding NaCl and Na 2 SO 4 to the DI water, increased the corrosion rate, proportionally to the concentration. In t...
Effect of CO2 corrosion behavior of mild steel in oilfield produced water
Journal of Loss Prevention in the Process Industries, 2015
The corrosion rates of API X65 mild steel alloy in CO 2 e containing produced water have been studied by weight loss technique, potentiodynamic polarization technique and characterization of the corroded surface techniques. The effect of temperature, speed of rotation, pH and acetic acid concentration were studied. The optimum condition in presence and absence of protective film were also addressed. The kinetic parameters and reaction behavior were discussed in details. Corrosion rates increases with increasing temperature, acetic acid concentration, and speed of rotation, and decreased with increasing solution pH. The primary corrosion product of API X65 mild steel is ferrous carbonate (FeCO 3) at high temperatures, high pH's (alkaline media) and absence of acetic acid, which could act as a protective film so that CO 2 corrosion rate can be reduced.
International journal of electrochemical science
The effect of increasing the immersion time form 1 h to 24 h on the corrosion behavior of API X-70 pipeline steel in 4.0 wt. % NaCl solution was reported using different electrochemical and spectroscopic techniques. The cyclic potentiodynamic polarization (CPP) measurements indicated that increasing the time of immersion decreases the anodic, cathodic and corrosion currents. Chronoamperometric current-time (CCT) experiments at-0.5 and-0.35 V vs. Ag/AgCl showed that the absolute current of the steel decreases with increasing immersion time and that pitting corrosion occurs only at-0.35 V as indicated also by scanning electron microscope images. Electrochemical impedance spectroscopy (EIS) confirmed the results obtained by CPP and CCT that the increase of immersion time from 1 h to 24 h increases both the solution and polarization resistances. Results together were consistent with each other confirming that the corrosion of API X-70 5L pipeline steel in 4.0 wt. % NaCl solution decreas...