Showing papers in "Corrosion in 2014"
TL;DR: In this paper, the internal corrosion of mild steel in the presence of hydrogen sulfide (H2S) represents a significant challenge in oil production and natural gas treatment facilities, but the underlying mechanisms involved in H2S corrosion are still not fully understood.
Abstract: The internal corrosion of mild steel in the presence of hydrogen sulfide (H2S) represents a significant challenge in oil production and natural gas treatment facilities, but the underlying mechanisms involved in H2S corrosion are still not fully understood. This lack of knowledge makes the prediction, prevention, and/or control of aqueous H2S corrosion of mild steel much more difficult. In the present study, H2S corrosion mechanisms were experimentally investigated in short-term corrosion tests (lasting 1 h to 2 h), conducted in a 1 wt% sodium chloride (NaCl) solution at different pH (pH 2 to pH 5), at different temperatures (30°C to 80°C), under various H2S/N2 gaseous concentration ratios (0 to 10%[v]) and flow rates, using a X65 mild steel rotating cylinder electrode. Corrosion rates were measured by linear polarization resistance (LPR). Corrosion mechanisms were investigated by using potentiodynamic sweeps and by comparison with electrochemical modeling. LPR results showed that corrosion rates increase...
103 citations
TL;DR: In this article, the best prediction model for H2S solubility and dissociation in an H 2S-H2O system was identified by comparing with experimental data, and it was found that, in short-term exposures, mackinawite formed at 25°C, while greigite and pyrite were detected at 60°C.
Abstract: Expanding the basic knowledge required for improved understanding of hydrogen sulfide (H2S) corrosion of mild steel is needed. When it comes to even the most basic chemical descriptors of aqueous H2S systems such as H2S solubility, water chemistry, polymorphism of iron sulfide, the formation or dissolution of iron sulfide scale, and its protectiveness, many open questions persist and more investigation is required. Inconsistencies in prevailing expressions for H2S solubility constant (KH2S), the first dissociation constant (Ka,1), and the second dissociation constant (Ka,2) are reviewed here. By comparing with experimental data, the best prediction model for H2S solubility and dissociation in an H2S–H2O system was identified. Occurrence of iron sulfide polymorphs was experimentally investigated and it was found that, in short-term exposures, mackinawite formed at 25°C, while greigite and pyrite were detected at 60°C. The solubility limits for these iron sulfides were determined. Simplified Pourbaix diagra...
86 citations
TL;DR: A compilation of the reported corrosion potentials for Mg alloys and selected intermetallic compounds is presented in this article, based on a collection of data collected from the National Institute of Standards and Technology (NIST).
Abstract: A compilation of the reported corrosion potentials for Mg alloys and selected intermetallic compounds is presented. This study presents a galvanic series for Mg alloys based on a collection of data...
73 citations
TL;DR: In this article, the stability of a protective iron carbonate layer has been studied at 80°C over a relatively wide range of bulk pH, and experimental results confirmed a pseudo-passive behavior, indicated by a positive shift in the opencircuit potential and a significantly retarded corrosion rate for systems at pH 6.0 and above.
Abstract: The iron carbonate corrosion product layer formed on mild steel in carbon dioxide (CO2) environments is known to retard corrosion. When not fully covering the steel surface, it may also lead to initiation of localized corrosion, due to a galvanic effect. In this work, the stability of a protective iron carbonate layer has been studied at 80°C over a relatively wide range of bulk pH. Experiments were done in a glass cell using a three-electrode system. Electrochemical techniques such as linear polarization resistance (LPR) and potentiodynamic polarization (PP) were used. Surface analysis techniques (scanning electron microscopy [SEM], x-ray diffraction [XRD], and transmission electron microscopy [TEM]) were used to confirm the composition and structure of the protective layer. Experimental results confirmed a pseudo-passive behavior, indicated by a positive shift in the open-circuit potential and a significantly retarded corrosion rate for systems at pH 6.0 and above. However, a stable and protective pseud...
65 citations
TL;DR: In this article, procedures and parameters that enable identification of, or discrimination between, general and localized corrosion processes through electrochemical noise are discussed and their relevant similarities, differences, and interdependences are indicated.
Abstract: In this paper, procedures and parameters that enable identification of, or discrimination between, general and localized corrosion processes through electrochemical noise are critically discussed. Their relevant similarities, differences, and interdependences are indicated. In addition, the relation between different procedures and parameters with the underlying physicochemical processes is indicated. Consistent and reliable information can be obtained from electrochemical noise data when a data analysis procedure is selected, which on the one hand has a high discrimination ability and on the other hand yields a descriptive parameter that is directly associated to the underlying physico-chemical process. Procedures that meet these two requirements appear to be the Hilbert-Huang transform (Hilbert spectrum), wavelet transform (energy distribution plot), and the analysis of charge and frequency of corrosion events. In addition to the procedures that meet these two requirements, some of the descriptive parameters can be determined by different analysis procedures, which increase their reliability.
55 citations
TL;DR: In this paper, steel coupons were exposed to a supercritical carbon dioxide (CO2) environment in which water contamination was deliberately added over the range from 100 ppmw to 50,000 ppmw.
Abstract: Steel coupons were exposed to a supercritical carbon dioxide (CO2) environment in which water contamination was deliberately added over the range from 100 ppmw to 50,000 ppmw. Exposure was carried ...
53 citations
TL;DR: The localized corrosion susceptibility of a clean grade of Type 304 (UNS S30400) stainless steel (SS304), which was processed with the intent of having fewer and smaller inclusions, was compared in this paper.
Abstract: The localized corrosion susceptibility of a clean grade of Type 304 (UNS S30400) stainless steel (SS304), which was processed with the intent of having fewer and smaller inclusions, was compared wi...
49 citations
TL;DR: In this article, the effects of Cr, Mo, and W on the crevice corrosion of commercial Ni-Cr-Mo(W) alloys in 1.0 mol/L sodium chloride (NaCl) were studied using the potentiodynamic-galvanostaticpotentiod.
Abstract: The effects of Cr, Mo, and W on the crevice corrosion of a number of commercial Ni-Cr-Mo(W) alloys in 1.0 mol/L sodium chloride (NaCl) were studied using the potentiodynamic-galvanostatic-potentiod...
49 citations
TL;DR: In this article, the effect of prior cold work (10, 20, and 40% reduction in thickness) on hydrogen diffusion and trapping was investigated using both Devanathan permeation and thermal desorption methods.
Abstract: The effect of prior cold work (10, 20, and 40% reduction in thickness) on hydrogen diffusion and trapping was investigated using both Devanathan permeation and thermal desorption methods. The first...
48 citations
TL;DR: In this paper, an electrochemical review on the corrosion behavior of iron and steel in bicarbonate and carbonate solutions is presented, where the mechanisms of dissolution and passivation are at first consolidated.
Abstract: This paper presents an electrochemical review on the corrosion behavior of iron and steel in bicarbonate and carbonate solutions. The mechanisms of dissolution and passivation are at first consolid...
47 citations
TL;DR: Corrosion performance of austenitic-ferritic (duplex) stainless steels UNS S32101, S32202, S 32304, and S32205 was studied in the presence of ch...
Abstract: Corrosion performance of austenitic-ferritic (duplex) stainless steels UNS S32101, S32202, S32304, and S32205 and austenitic stainless steels UNS S30403 and S31603 was studied in the presence of ch...
TL;DR: Acetic acid (CH3COOH) is recognized as an important factor in mild steel corrosion as discussed by the authors, similar to carbonic acid (H2CO3) present in carbon dioxide (CO2)-saturated aqueous environments.
Abstract: 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...
TL;DR: In this paper, the authors evaluated the corrosion properties of carbon steel in supercritical carbon dioxide (CO2)/brine mixtures related to the deep water oil production development, and the results showed that the corrosion rates at 65°C showed a high corrosion rate (~10 mm/y) and a slight difference with pressure.
Abstract: The objective of the present study was to evaluate the corrosion properties of carbon steel in supercritical carbon dioxide (CO2)/brine mixtures related to the deep water oil production development. Corrosion tests were performed in 25 wt% sodium chloride (NaCl) solution under different CO2 partial pressures (4, 8, 12 MPa) and temperatures (65°C, 90°C). Corrosion behavior of carbon steel was evaluated using electrochemical methods (linear polarization resistance [LPR] and electrochemical impedance spectroscopy [EIS]), weight-loss measurements, and surface analytical techniques (scanning electron microscopy [SEM], energy-dispersive x-ray spectroscopy [EDS], x-ray diffraction [XRD], and infinite focus microscopy [IFM]). The corrosion rates measured at 65°C showed a high corrosion rate (~10 mm/y) and a slight difference with pressure. Under these conditions, the sample surface was locally covered by iron carbide (Fe3C), which is porous and non-protective. However, the corrosion rates measured at 90°C increas...
TL;DR: In this article, the effect of quaternary alloying additions to aluminum alloy (AA)5083 (Al-4.4Mg-0.5Mn [UNS A95083]) was investigated.
Abstract: The calculated effect of a range of quaternary alloying additions to aluminum alloy (AA)5083 (Al-4.4Mg-0.5Mn [UNS A95083]) was investigated. Attention was given to the influence of composition on the volume fraction of β-phase (Mg2Al3), and the possible formation of any additional phases (which we term γ-phase herein). Alloying additions of silver, cerium, copper, lithium, neodymium, nickel, scandium, silicon, strontium, yttrium, zinc, and zirconium were studied in hypothetical additions of 0.1 wt% and 0.5 wt%, revealing that there is potential to modify the fraction of β-phase, and hence sensitization, in AA5083. Calculations indicated strontium to be the most effective addition in decreasing β-phase fraction during thermal exposure (sensitization); therefore, the influence of Sr additions were studied empirically via production of custom Al-Mg-Mn alloys. Sensitization was investigated via the nitric acid mass loss test (NAMLT), revealing that mass loss from intergranular corrosion decreased by more than...
TL;DR: In this paper, the use of Bayesian network models for assessing the probability of corrosion in pipelines is discussed. But, the authors focus on the case of internal corrosion and external corrosion of oil and gas pipelines.
Abstract: Corrosion processes mainly affect the probability of failure, which then leads to consequences, such as, fire, explosion, or environmental damage. This paper focuses on the use of Bayesian network models for assessing the probability of corrosion. The Bayesian network approach incorporates cause- effect relationships of complex systems in the form of conditional probabilities. This method considers both knowledge uncertainties (i.e., modeling uncertainties) and data uncertainties to make more informed decisions. The Bayes theorem allows the model to predict the probability of events from their causes, and, if a particular event is known to have occurred, predict probable causes of that event. Two case studies, the first one involving internal corrosion and the second involving external corrosion of oil and gas pipeline, are presented, along with validation using field measurements. The extension of the approach to predicting stress corrosion cracking of pipelines is discussed.
TL;DR: Corrosion behavior of zinc exposed to a tropical marine atmosphere for 4 years was investigated in this article, which showed an obvious decrease in the corrosion rate, which was attributed to the developmen...
Abstract: Corrosion behavior of zinc exposed to a tropical marine atmosphere for 4 years was investigated. The results showed an obvious decrease in the corrosion rate, which was attributed to the developmen...
Journal Article•
TL;DR: In this paper, a model sulfur compound and model naphthenic acids were used to mimic the corrosion by crude fractions in the present study, and the iron sulfide scale formed by the model sulfur/acid compounds was challenged by naphthensic acids under high-velocity conditions to examine its protectiveness against corrosion.
Abstract: Corrosive naphthenic acids and sulfur compounds in crude oils present a major challenge for refineries from a corrosion perspective. Although it is accepted that some sulfur compoundsmay form protective FeS scales on themetal surface and deter corrosion, attempting to correlate the characteristics of FeS scale with its protective properties has not been successful. Given the complex chemical compositions of real crudes, model sulfur compound and model naphthenic acids were used to mimic the corrosion by crude fractions in the present study. The iron sulfide scale formed by the model sulfur/acid compounds was challenged by naphthenic acids under high-velocity conditions to examine its protectiveness against corrosion.Moreover, the scalewas analyzedwith transmission electron microscope/energy dispersive X-ray spectroscopy technique, and a layer of iron oxide formed on the 5Cr steel was found when naphthenic acids were present in the solution. The iron oxide layer appeared to be important for maintaining protection against naphthenic acid corrosion, and further analysis revealed that it was composed of magnetite. Copyright © 2015 John Wiley & Sons, Ltd.
TL;DR: In this paper, the authors investigated the stress corrosion cracking and the electrochemical behavior of an API X70 pipeline steel in a simulated acidic soil solution using slow strain rate testing (SSRT), electr...
Abstract: The stress corrosion cracking (SCC) and the electrochemical behavior of an API X70 pipeline steel in a simulated acidic soil solution were investigated using slow strain rate testing (SSRT), electr...
TL;DR: The development of materials possessing the ability to recover their main function(s) in response to destructive impacts is, today, one of the most rapidly growing fields in material science.
Abstract: Development of materials possessing the ability to recover their main function(s) in response to destructive impacts is, today, one of most rapidly growing fields in material science. In particular...
TL;DR: Magnesium-rich primer, in a non-topcoated, scribed condition, was utilized for the corrosion protection of an aluminum alloy (AA)2024-T351 (UNS A92024) substrate as mentioned in this paper.
Abstract: Magnesium-rich primer, in a non-topcoated, scribed condition, was utilized for the corrosion protection of an aluminum alloy (AA)2024-T351 (UNS A92024) substrate. Exposures were conducted in the fi...
TL;DR: In this article, pitting and weight loss of carbon steel (CS) coupons due to corrosion caused by a sulfate-reducing bacteria (SRB) culture were examined over a 40-day period after the organic substrate had been exhausted.
Abstract: Sulfate-reducing bacteria (SRB) are known as potential promoters for microbiologically influenced corrosion (MIC). Many researchers have studied the SRB-induced corrosion in the presence of organic nutrients. However, SRB-metabolizable organics are not constantly present in corroding environments. In this study, pitting and weight loss of carbon steel (CS) coupons due to corrosion caused by a SRB culture were examined over a 40-day period after the organic substrate had been exhausted. The extents of pitting corrosion on the polished and unpolished sides of the coupons were also compared to investigate the effect of roughness. The study was done in reactors with constant bubbling of nitrogen to ensure the anoxic condition (verified by the redox indicator resazurin). The surface structure of biofilm was observed using scanning electron microscopy (SEM). Pit depth, density, and morphology were examined using infinite focus microscopy (IFM). The SRB, surviving through the 40-day starvation of an organic ener...
TL;DR: In this article, the authors compared the stress corrosion cracking (SCC) resistance of materials used at the present time for steam generator (SG) tubing in pressurized water reactor (PWR) primary water.
Abstract: The purpose of this research was to compare the stress corrosion cracking (SCC) resistance of materials used at the present time for steam generator (SG) tubing in pressurized water reactor (PWR) primary water. Our results in PWR primary water for 20% cold-worked (CW) Alloy 800 (UNS N08800) are compared with already published data for SCC growth from 20%CW Alloy thermally treated (TT)690 (UNS N06690), 20%CW Alloy mill-annealed (MA)600 (UNS N06600), and 20%CW austenitic stainless steels. The second purpose was to examine the dependence of SCC growth on nickel and chromium in PWR primary water; the objective was to obtain the basic knowledge to understand SCC behavior of SG tubing materials. The third objective was to understand whether accelerated testing at higher temperatures is appropriate for predicting SCC initiation and growth at lower temperatures. For these objectives, SCC growth was measured in PWR primary water at 290, 320, 330, 340, and 360°C under static load conditions. Tests were performed us...
TL;DR: A test sample incorporating a painted Al alloy panel, uncoated through-hole fasteners, and scribes has recently been shown to provide an accelerated response during atmospheric corrosion testing in this article.
Abstract: A test sample incorporating a painted Al alloy panel, uncoated through-hole fasteners, and scribes has recently been shown to provide an accelerated response during atmospheric corrosion testing in...
TL;DR: In this article, an active corrosion protection system consisting of organic-inorganic hybrid sol-gel coating impregnated with inhibitor-loaded nanocontainers is described. But it is not shown how to apply it to real-world applications.
Abstract: The present work describes the development of an active corrosion protection system consisting of organic-inorganic hybrid sol-gel coating impregnated with inhibitor-loaded nanocontainers. Hollow m...
TL;DR: In this article, the properties of an adsorbed corrosion inhibitor (tall oil fatty acid (TOFA) imidazolium chloride) on mica, gold, and X65 steel were studied using in situ atomic force microscopy (AFM).
Abstract: The properties of an adsorbed corrosion inhibitor—tall oil fatty acid (TOFA) imidazolium chloride—on mica, gold, and X65 steel were studied using in situ atomic force microscopy (AFM). Topography i...
TL;DR: In this article, as-cast Ni-Al bronze (NAB) was subjected to friction stir processing (FSP) and different processing parameters including rotating rate, traverse speed, and processing passes were selected to investigate the process.
Abstract: As-cast Ni-Al bronze (NAB) was subjected to friction stir processing (FSP). Different processing parameters including rotating rate, traverse speed, and processing passes were selected to investiga...
TL;DR: In this article, the performance of UNS N06690TT and N08800SN in simulated PWR primary water with three concentrations of dissolved oxygen (DO) was studied by open-circuit potential (OCP), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), x-ray photoelectron spectroscopic (XPS), and transmission electron microscope (TEM).
Abstract: Corrosion behaviors of UNS N06690TT and N08800SN in simulated pressurized water reactor (PWR) primary water containing three concentrations of dissolved oxygen (DO) was studied by open-circuit potential (OCP), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). These results have shown that DO in simulated PWR primary water produces a strong effect on Cr dissolution. At DO < 0.01 ppm, the electrochemical impedance of N06690TT at low frequency gradually increases and becomes larger than that of N08800SN, and N06690TT shows slightly better corrosion resistance than N08800SN. At DO ≥ 0.1 ppm, the electrochemical impedance of N06690TT at low frequency rapidly decreases and becomes lower than that of N08800SN with the increase of immersion time; N08800SN shows much better corrosion resistance than N06690TT. The spinel oxides NiFe2O4 or Fe3O4 can form in the inner oxide layer on N08800SN due to rela...
TL;DR: In this paper, the corrosion behavior of titanium was studied in sulfuric acid solutions with different additions of Cl−, Cu2+, and Fe3+ to simulate hydrometallurgical lixiviants at 25, 55, and 85°C.
Abstract: Titanium is chosen as the construction material of autoclaves for pressure acid leaching of metal ores. The corrosion behavior of titanium was studied in sulfuric acid solutions with different additions of Cl−, Cu2+, and Fe3+ to simulate hydrometallurgical lixiviants at 25, 55, and 85°C. Electrochemical methods like open-circuit potential measurement, potentiodynamic polarization, potentiostatic polarization, and electrochemical impedance spectroscopy (EIS) were used to study the influence of these ions on the corrosion response of titanium in sulfuric acid. The chemical composition of titanium oxide films was examined further using x-ray photoelectron spectroscopy (XPS). Potentiodynamic polarization experiments demonstrated that the presence of Cl−, Cu2+, and Fe3+ facilitated the anodic passivity of titanium in sulfuric acid. EIS experiments showed that modest addition of Fe3+ (1.0 g/L) increased the polarization resistance most significantly. Both electrochemical experiments and surface analysis showed ...
TL;DR: In this paper, the authors examined manganese sulfide (MnS) inclusions in steel rebar exposed to a simulated concrete pore solution to understand their role in passive film, corrosion, and pit propagation behavior.
Abstract: This study examined manganese sulfide (MnS) inclusions in steel rebar exposed to a simulated concrete pore solution to understand their role in passive film, corrosion, and pit propagation behavior. The passive film was characterized using x-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, and electrochemical techniques. The results showed that MnS inclusions adversely affected the nature of the passive film and accelerated corrosion and pit formation. A schematic model was developed to explain the deterioration of passive film formed on steel containing MnS inclusions, and was validated by Raman spectroscopy of the resulting rust formed on such steel.
TL;DR: In this paper, an innovative model to predict corrosion in reinforced concrete structures is presented, incorporating potential dependence and corrosion macrocell effects, which integrates the initiation and the propagation stages of corrosion in a single predictive model.
Abstract: The chloride corrosion threshold of steel in concrete depends not only on concrete and steel properties but also on the potential of the steel while it is still in the passive condition. An innovative model to predict corrosion in reinforced concrete structures is presented, incorporating potential dependence and corrosion macrocell effects. The novel approach integrates the initiation and the propagation stages of corrosion in a single predictive model. The model is applied to a generic, partially submerged, reinforced concrete marine pile. The purpose of this paper was to establish and illustrate the concept of a functional approach to implement potential-dependent chloride threshold in corrosion damage projections, plus articulation of the initiation and propagation stages, in one predictive model. The long-term damage projection results are markedly lower contrasted with those of an identical system with a time-invariant chloride threshold. The results show that implementing chloride threshold depende...