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Добірка наукової літератури з теми "Corrosion in the conditions of sulfate reduction"

Автор: Grafiati

Опубліковано: 30 травня 2022

Оновлено: 31 травня 2022

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Статті в журналах з теми "Corrosion in the conditions of sulfate reduction"

Enning, Dennis, and Julia Garrelfs. "Corrosion of Iron by Sulfate-Reducing Bacteria: New Views of an Old Problem." Applied and Environmental Microbiology 80, no. 4 (December 6, 2013): 1226–36. http://dx.doi.org/10.1128/aem.02848-13.

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ABSTRACTAbout a century ago, researchers first recognized a connection between the activity of environmental microorganisms and cases of anaerobic iron corrosion. Since then, such microbially influenced corrosion (MIC) has gained prominence and its technical and economic implications are now widely recognized. Under anoxic conditions (e.g., in oil and gas pipelines), sulfate-reducing bacteria (SRB) are commonly considered the main culprits of MIC. This perception largely stems from three recurrent observations. First, anoxic sulfate-rich environments (e.g., anoxic seawater) are particularly corrosive. Second, SRB and their characteristic corrosion product iron sulfide are ubiquitously associated with anaerobic corrosion damage, and third, no other physiological group produces comparably severe corrosion damage in laboratory-grown pure cultures. However, there remain many open questions as to the underlying mechanisms and their relative contributions to corrosion. On the one hand, SRB damage iron constructions indirectly through a corrosive chemical agent, hydrogen sulfide, formed by the organisms as a dissimilatory product from sulfate reduction with organic compounds or hydrogen (“chemical microbially influenced corrosion”; CMIC). On the other hand, certain SRB can also attack iron via withdrawal of electrons (“electrical microbially influenced corrosion”; EMIC),viz., directly by metabolic coupling. Corrosion of iron by SRB is typically associated with the formation of iron sulfides (FeS) which, paradoxically, may reduce corrosion in some cases while they increase it in others. This brief review traces the historical twists in the perception of SRB-induced corrosion, considering the presently most plausible explanations as well as possible early misconceptions in the understanding of severe corrosion in anoxic, sulfate-rich environments.

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Nicoletti, Danika, Mohita Sharma, and Lisa M. Gieg. "Assessing Microbial Corrosion Risk on Offshore Crude Oil Production Topsides under Conditions of Nitrate and Nitrite Treatment for Souring." Microorganisms 10, no. 5 (April 29, 2022): 932. http://dx.doi.org/10.3390/microorganisms10050932.

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Oilfield souring is a detrimental effect caused by sulfate-reducing microorganisms that reduce sulfate to sulfide during their respiration process. Nitrate or nitrite can be used to mitigate souring, but may also impart a corrosion risk. Produced fluids sampled from the topside infrastructure of two floating, production, storage, and offloading (FPSO) vessels (Platform A and Platform B) were assessed for microbial corrosion under nitrate and nitrite breakthrough conditions using microcosm tests incubated at 54 °C. Microbial community compositions on each individual FPSO were similar, while those between the two FPSO vessels differed. Platform B microbial communities responded as expected to nitrate breakthrough conditions, where nitrate-reducing activity was enhanced and sulfate reduction was inhibited. In contrast, nitrate treatments of Platform A microbial communities were not as effective in preventing sulfide production. Nitrite breakthrough conditions had the strongest sulfate reduction inhibition in samples from both platforms, but exhibited the highest pitting density. Live experimental replicates with no nitrate or nitrite additive yielded the highest general corrosion rates in the study (up to 0.48 mm/year), while nitrate- or nitrite-treated fluids revealed general corrosion rates that are considered low or moderate (<0.12 mm/year). Overall, the results of this study provide a description of nitrogen- and sulfur-based microbial activities under thermophilic conditions, and their risk for MIC that can occur along fluid processing lines on FPSO topsides that process fluids during offshore oil production operations.

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Vyšvařil, Martin, and Markéta Rovnaníková. "Study of Fine-Grained Composites Exposed to Sulfuric Acid and Sodium Sulfate." Applied Mechanics and Materials 827 (February 2016): 275–78. http://dx.doi.org/10.4028/www.scientific.net/amm.827.275.

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The degradation of concrete due to ingress of sulfate ions from the environment plays an important role in the durability of concrete constructions, especially in sewage collection systems where concrete sewer pipes are exposed to sulfates from waste water and from biogenic activity of bacteria. During this process the pH of the surface of concrete sewer pipes is reduced and it may lead to the steel depassivation and results in the corrosion of steel reinforcement. Damage due to sulfate interaction can result in the cracking and softening, with loss of strength of concrete. This paper is focused on the sulfate attack on fine-grained concrete where the effect of one-year contact of 0.5% H2SO4, and 5% Na2SO4 on changes of pH and content of sulfates in 7 types of concrete has been analyzed. It was found that after one year of sulfate attack on concrete, significant growth of content of sulfates is observed in the lowermost layer of the samples. Samples treated by 5% Na2SO4 contain slightly more sulfates in the upper layers than samples treated by sulfuric acid. The reduction in pH of aqueous leaches occurred in all layers of the samples. However, even in the lower layers of the samples, the reduction of pH below 9.5 did not turn up (except for SRS sample), and thus the conditions for the depassivation of reinforcement were not met.

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Boontian, Nittaya. "Effect of Zero Valent Iron (ZVI) in Wastewater Treatment: A Review." Applied Mechanics and Materials 775 (July 2015): 180–84. http://dx.doi.org/10.4028/www.scientific.net/amm.775.180.

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Cathodic hydrogen was produced in the presence of anaerobic zero valent iron (ZVI) corrosion by water. It can enhance microbial denitrification to convert nitrate to N2O and N2. Autotrophic denitrifying growth on ZVI can enhance nitrate removal. Results showed that by increasing nitrate removal rates, innocuous gases (N2O and N2) are produced rather than ammonium. Using steel wool with a small specific surface area instead of powdered ZVI, pH was not significantly increased. Little pH change was caused by corrosion. This is a positive condition for autotrophic denitrifying bacteria. ZVI was used in permeable reactive barriers (PRBs) process under anaerobic conditions. It used sulfate reducing bacteria for immobilization of heavy metals. In fermentation, methanogenesis and sulfate reduction was complete after adding ZVI to mixed anaerobic cultures. It was found that methane production increased and sulfate was reduced. This was due to readily utilizable ZVI which served as a slow-release electron donor for methanogenesis and sulfate reduction. ZVI has potential as a useful material in bioremediation.

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Choung, Y. K., and S. J. Jeon. "Phosphorus removal in domestic wastewater using anaerobic fixed beds packied with iron contactors." Water Science and Technology 41, no. 1 (January 1, 2000): 241–44. http://dx.doi.org/10.2166/wst.2000.0035.

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The objective of this study is to develop an alternative phosphorus removal system for small-scale plants disposing domestic wastewater. In order to promote anaerobic microbial corrosion by sulfate reducing bacteria (SRB), a bench-scale upflow anaerobic fixed bed (UAFB) packed with iron contactors was installed, and operated to investigate the treatment characteristics of domestic wastewater from an apartment complex. It was found that there is a linear relationship between anaerobic corrosion and sulfate reduction by SRB within the range of operational conditions. As the results of introducing the UAFBs prior to an anoxic/oxic process, phosphorus removal efficiencies were enhanced with no adverse effects on nitrification and denitrification.

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Fang, Xiao Jun, Li Liu, Zhi Gang Yang, and Yong Qiang Zhang. "Preparation and Performance Evaluation of a Novel Bactericide for Sulfate Reducing Bacteria." Materials Science Forum 1035 (June 22, 2021): 624–29. http://dx.doi.org/10.4028/www.scientific.net/msf.1035.624.

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The sulfate reducing bacteria (SRB) bactericide was synthesized using KNO3, isothiazolinone, quaternary ammonium salt, and additives as main components, and the optimal ratio and critical concentration of the bactericide were determined. Weight loss method, potentiodynamic polarization curve, compatibility study were used to investigate the changes of corrosion rate and corrosion current density and compatibility after adding the bactericide. The results showed that the optimal formula ratio of the bactericide was: KNO3: isothiazolinone: quaternary ammonium salt: additive is 20:1:2:3, and the critical concentration of the bactericide was 50 mg/L. The addition of bactericides reduced the corrosion rate of pipes by 67% to 88%, and the electrochemical corrosion current density of pipes was significantly reduced, indicating that the presence of bactericides under the given media conditions significantly slowed down the corrosion process of metals. The bactericide was used in conjunction with commonly used oilfield chemicals such as corrosion inhibitors, scale inhibitors, flocculants, without obvious changes in appearance, no reduction in efficacy. Therefore, it may be concluded that the bactericide has good compatibility.

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Ehsani, Ali, Mohammad Ghasem Mahjani, Maryam Nasseri, and Majid Jafarian. "Influence of electrosynthesis conditions and Al2O3 nanoparticles on corrosion protection effect of polypyrrole films." Anti-Corrosion Methods and Materials 61, no. 3 (April 29, 2014): 146–52. http://dx.doi.org/10.1108/acmm-07-2012-1193.

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Purpose – The purpose of this paper was to investigate the anti-corrosion behavior of polypyrrole (PPy) films in different states and presence of alumina nanoparticles synthesized by galvanostatic electropolymerization on stainless steel (SS) electrodes in an artificial seawater solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Design/methodology/approach – The electrochemical measurements were used to examine the effects of PPy and its nanocomposite on the corrosion behavior of SS type 316L in artificial seawater. A standard electrochemical cell with three electrodes was used for the measurements. The electrochemical response of the coated electrodes in the doped and the undoped state was compared with that of a bare electrode. Corrosion rate information was obtained by the Tafel extrapolation method, where the intersection point of a cathodic and an anodic polarization curve provides both the corrosion potential and the corrosion current. EIS measurements confirmed the potentiodynamic and open circuit potential (OCP) results. The microstructure of the obtained films was investigated by scanning electron microscopy. Findings – The results showed that the coated polymer films shifted the electrode potential toward more positive potentials, but this shift did not lead to passivation. However, a notable synergy was observed between PPy undoped film, oxygen reduction and iron dissolution. The potential of the SS remained in the active dissolution region, and it was not possible to produce a passive oxide layer in this region. PPy separates the metal dissolution process from the oxygen reduction process. This would prevent the local pH increase at the metal surface and subsequent delamination. The polarization curves, EOCP and impedance measurements showed that PPy undoped/Al2O3 layers show promise as good candidates for the corrosion protection of reactive metals. Originality/value – This paper presents that electrodes coated with undoped PPy synthesized in the presence of dodecyl sulfate anions and Al2O3 nanoparticles offered a noticeable enhancement of protection against corrosion processes.

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García-Ávila, Fernando, Lía Ramos-Fernández, and César Zhindón-Arévalo. "Estimation of corrosive and scaling trend in drinking water systems in the city of Azogues, Ecuador." Ambiente e Agua - An Interdisciplinary Journal of Applied Science 13, no. 5 (October 1, 2018): 1. http://dx.doi.org/10.4136/ambi-agua.2237.

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The quality of drinking water flowing in a distribution network can possess corrosive characteristics that may cause the material degradation of pipes and accessories. This problem can result in reduction of the service life of pipes and create a major public health problem. The agreement between the physical-chemical water quality analysis and national standards are not enough to confirm the balance of the water quality in terms of corrosion. In order to predict pipe corrosion in water distribution system networks, the corrosive trend was evaluated using the Langelier (LSI), Ryznar (RSI), and Larson-Skold (LRI) indexes based on measurements of pH, temperature, total dissolved solids, alkalinity, calcium hardness, sulfate and chloride. This study was setup with 180 samples collected in six zones of the distribution network, from July to December of 2017, according to the standard methods for the analysis of drinking water. The results indicate a variation of the LSI from -1.22 to -1.68; RSI from 9.75 to 10.52 and LRI from 0.46 to 0.77. A linear model was fitted for each index to predict the corrosion with the water quality conditions of this study case. Therefore, the drinking water of the city of Azogues, Ecuador has a corrosive tendency from significant to severe. Corrosion indices were calculated to provide useful information on the water's corrosiveness. These results indicate the need to constantly monitor the corrosion rate in the distribution network and conduct a laboratory study to adjust effective parameters such as pH, in order to control corrosion.

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Vossoughi, M., and I. Alemzadeh. "A Study of Microbial Problems and Their Control in the Oilfield Waters." Water Science and Technology 25, no. 3 (February 1, 1992): 263. http://dx.doi.org/10.2166/wst.1992.0102.

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Microorganisms present in injection water or other oilfield water may cause corrosion or plugging of lines and reservoir formation rock. It should be pointed out that the mere presence of bacteria or other microorganisms in water does not necessarily mean that they present a problem. Elimination or reduction of bacteria is justified only if it represents an economical solution to a corrosion or plugging problem. This paper is an attempt to report the most important bacteria which grow in oilfield of Ahwaz (Iran), in order to control the action and their growth. Sulfate reducing bacteria (SRB) were the most important and damaging bacteria in this area. They cause corrosion, and the iron sulfide produced as a product of the corrosion reaction is an excellent,plugging material. The bacteria have been isolated from black deep sediments of a river in the neighbourhood of Ahwaz in which the sulfate concentration is high enough to promote the activity of SRB. The strains were first cultivated in anaerobic shakeflasks and progressively adapted to the culture contained carbohydrate and yeast extract as a model for primary experiment. The effect of the pH and temperature on the growth of bacteria under continuous cultivation show that the SRB grow under rather extreme conditions e.g. under pH ranging from 4 to 10, and temperature from 20 to 50°c.

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Chen, Shi Qiang, Dun Zhang, and Jia Jia Wu. "Influence of Sulfide on Oxygen Reduction Reaction in 3.5% Sodium Chloride Solution." Advanced Materials Research 581-582 (October 2012): 104–7. http://dx.doi.org/10.4028/www.scientific.net/amr.581-582.104.

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Different from the corrosion under anaerobic conditions, oxygen (O2) takes part in the cathodic reaction under aerobic conditions. Sulfate-reducing bacteria (SRB) have been regarded for many years as strictly anaerobic bacteria, but recently, they are found to be able to survive in the presence of O2, and how they affect the oxygen reduction reaction (ORR) has not been clear. In this study, the role of sulfide, a key inorganic metabolite of SRB, in ORR has been investigated on Q235 carbon steel electrode with cyclic voltammetry and electrochemical impedance spectroscopy. Three cathodic processes are recorded on cyclic voltammograms in O2-saturated 3.5% NaCl solution: ORR, iron oxides reduction and hydrogen evolution. The peak current of ORR decreases with the introduction of sulfide, and finally vanishes when the sulfide concentration is more than 0.5 mM. EIS reveals that sulfide leads to the disappearance of the feature of semi-infinite diffusion of ORR and the fitting results demonstrate that charge transfer resistance increases with increasing sulfide concentration. Therefore sulfide hinders the cathodic reduction of O2on Q235 carbon steel in 3.5% NaCl solution.

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Дисертації з теми "Corrosion in the conditions of sulfate reduction"

Zhao, Weijie. "Corrosion initiation induced by sodium sulfate and sodium chloride particles on Cu and the golden alloy Cu5Al5Zn at simulated atmospheric conditions." Thesis, KTH, Materialvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-219471.

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Effects of sodium sulfate (Na2SO4) particle deposition on the atmospheric corrosion of copper (Cu) metal and a Cu-based alloy (Cu5Al5Zn) used in architectural applications were investigated at laboratory conditions compared with effects induced by sodium chloride (NaCl) and to some extent ammonium sulfate (NH4)2SO4 induced corrosion. Pre-deposited surfaces were exposed to repeated wet/dry conditions in a climatic chamber and the formation of corrosion products were assessed using light optical microscopy (LOM), scanning electron microscopy with elemental analysis (SEM/EDS), Fourier transform infrared techniques (FTIR microscopy) and cathodic reduction (CR). Na2SO4 induced corrosion resulted in corrosion cells locally over the surface on both Cu and Cu5Al5Zn, of increased oxygen content in the anodic area of the cells (center of pre-deposited area). The main corrosion products formed on Cu metal are basic copper sulfates and cuprite (Cu2O), while basic sulfates (copper and/or zinc) and Cu2O were the main corrosion products formed on Cu5Al5Zn. A combined deposition of Na2SO4 + NaCl was carried out on the Cu5Al5Zn alloy using two different deposition methods to investigate the possible interplay from a corrosion initiation perspective between the two salt particles. For short time exposed Cu5Al5Zn (1 cycle), two different corrosion cells formed, mainly induced by Na2SO4 and NaCl. Corrosion products formed in anodic areas of a Na2SO4 induced corrosion cell were similar to findings observed for Cu5Al5Zn pre-deposited with Na2SO4 only, whereas peripheral cathodic areas primarily were affected by NaCl dissolution and predominantly composed of Cu2O that was the main corrosion product with small amount of hydroxides and carbonates of the NaCl induced corrosion cells. After relatively longer exposure periods (2 and 6 wet/dry cycles), NaCl dominated the corrosion of the entire surface with the formation of more Cu2O, hydroxides and carbonates. Cathodic reduction findings revealed a negative interplay on corrosion for the mixed salt after short time exposures (1 and 2 cycles), whereas a slight synergistic effect was evident after a longer exposure period (6 cycles), compared with corrosion induced by single salts.

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Погребова, Інна Сергіївна. "Наукові основи створення синергетичних адсорбційних інгібіторів корозії поліфункціонального призначення". Doctoral thesis, Київ, 2021. https://ela.kpi.ua/handle/123456789/45499.

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Дисертація присвячена вирішенню важливої науково-технічної проблеми: підвищенню корозійної стійкості та експлуатаційно-технічних властивостей металевих виробів, устаткування та пристроїв шляхом використання синергетичних адсорбційних інгібіторів корозії широкого спектру захисної дії. Розроблено науково-обґрунтований підхід до створення ефективних інгібіторів корозії на основі поліфункціональних органічних сполук та комбінацій органічних сполук і солей металів. Підхід базується на комплексному дослідженні процесів адсорбції, встановленні взаємозв’язку між будовою органічних сполук, їх адсорбційними захисними властивостями, визначенні особливостей кінетики парціальних реакцій конкретних видів корозії і шляхів впливу на них інгібіторів, врахуванні ефектів внутрішньомолекулярного і міжмолекулярного синергізму, які виникають при інгібуванні корозії. Досліджено закономірності адсорбції та захисної дії при кислотній корозії заліза та вуглецевих сталей різних за хімічним складом монофункціональних і поліфункціональних органічних сполук. Виявлена роль амінних, піридинієвих, карбонільних, тіокарбонільних, карбоксильних груп в захисній дії цих інгібіторів. Розвинені сучасні наукові положення щодо механізму захисної дії органічних інгібіторів корозії та ролі різних частинних ефектів її інгібування. Запропоновано і експериментально обґрунтовано рівняння, яке встановлює взаємозв’язок між кінетичними параметрами корозійних процесів, захисною дією інгібіторів та їх адсорбційними властивостями з урахуванням механізму анодного розчинення заліза. Досліджено і науково обґрунтовано ефекти внутрішньомолекулярного і міжмолекулярного синергізму, які виникають при інгібуванні корозії металів поліфункціональними органічними сполуками з атомами Нітрогену, Оксигену, Сульфуру та сумішами органічних і неорганічних сполук різного механізму захисної дії. Встановлено, що амінні та піридинові фрагменти поліфункціональних органічних сполук забезпечують їх захисну дію за енергетичним механізмом при невисоких температурах, а тіокарбонільних та карбоксильних – при підвищених. Висвітлено взаємозв’язок між характером сил взаємодії між адсорбованими частинками та їх захисною дією при кислотній корозії заліза. Запропоновано новий тип синергетичних інгібіторів кислотної, сольової та лужної корозії цинку на основі сумішей органічних сполук і катіонів металів. Встановлено роль модифікації поверхневих властивостей цинку, що відбувається внаслідок протікання різних електрохімічних процесів в захисній дії цього типу інгібіторів корозії. Розроблена модель адсорбції органічних сполук на металах, заснована на уявленнях про утворення комплексів з частинним переносом заряду та прогнозуванні її протікання з використанням принципу ЖМКО Пірсона. На підставі застосування запропонованої моделі адсорбції розроблено напрямки створення нових ефективних інгібіторів корозії, засновані на врахуванні адсорбційних властивостей металів, специфіки механізмів корозії, ефектів синергізму їх захисної дії. Розроблено нову серію органічних інгібіторів корозії на основі четвертинних піридинієвих солей з карбонільними групами широкого спектру дії і поліфункціонального призначення (кислотна корозія, мікробна корозія металів в умовах бактеріальної сульфатредукції, кислотне корозійно-механічне руйнування сталей). Досліджено взаємозв’язок між захисною дією органічних сполук, електронними та стеричними властивостями їх замісників та природою додаткових функціональних угрупувань, схильних до безпосередньої адсорбції на сталі. Виявлено роль біологічного та електрохімічного факторів при інгібуванні корозії металів в умовах бактеріальної сульфатредукції. Науково обґрунтовано ефект синергізму захисної дії органічних сполук під впливом продуктів метаболізму бактерій (HS - , H S). Досліджено вплив інгібіторів на саморозряд, електричні та розрядні 2 характеристики цинкових та кадмієвих анодів хімічних джерел струму. На підставі використання розроблених інгібіторів корозії запропоновано удосконалені свинцево-цинкові та свинцево-кадмієві елементи з кислотними електролітами, марганцево-цинкові елементи водно-сольової та водно-лужної системи. Встановлена перспективність застосування комбінованого протикорозійного захисту вуглецевих сталей в водних агресивних середовищах на основі сумісного використання дифузійних покриттів та інгібіторів корозії.

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Liu, Bert C. Liu. "Joining Dissimilar Structural Alloys by Vaporizing Foil Actuator Welding: Process Conditions, Microstructure, Corrosion, and Strength." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1471629967.

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Eckert, Thomas. "The Influence of Sulfide Stress Conditions on the 34S-isotope Enrichment in Sulfate During Dissimilatory Sulfate Reduction." Thesis, 2009. http://hdl.handle.net/1807/32006.

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The purpose of this thesis was to experimentally investigate the influence of increasing sulfide concentrations on the 34S isotope enrichment in sulfate during dissimilatory sulfate reduction (DSR). Two independent batch culture experiments with different maximum sulfide concentrations of up to 20 mM in the first and up to 40 mM in the second experiment were conducted using the marine sulfate reducer Desulfobacter latus. A comparison of the results from both experiments revealed a distinct offset towards more positive δ34S(SO42-) values in the 'high-sulfide' experiment, compared to the 'low-sulfide' experiment. While a Rayleigh type fractionation model was able to match the slopes - i.e., enrichment factors - of both experiments, it failed to reproduce the proper y-axis intercept in the 'high-sulfide' experiment. I therefore propose a new fractionation model that allows for a backward flow of ambient H2S into the bacterial cell and a subsequent enzymatically mediated oxidation of H2S to sulfate. The new backward flow increases with elevated H2S concentrations and is described as a first order rate constant. Unlike a Rayleigh type fractionation model, my model explains the slope and y-intercept of both experiments with a single parameter set. The new model with H2S-reflux further suggests that it can be used to determine growth kinetic parameters like the half-saturation constant through δ34S measurements. These findings support the hypothesis of microbially mediated, bi-directional S-fluxes between oxidized and reduced sulfur species. Because the S-transport during DSR appears to be bi-directional, great care must be taken when evaluating culture experiments with a Rayleigh type fractionation model, owing to the fact that an evident S-backward flow violates the prerequisites for applying the Rayleigh model. A variable S-backward flow results in variable enrichment factors which increased from -11 (no H2S) to ≈-17 ‰ (40 mM of H2S) in my experiments. I show for the first time the significance of a bi-directional H2S transport across the cell membrane during DSR and its consequences for the 34S-isotope fractionation in sulfate.

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Частини книг з теми "Corrosion in the conditions of sulfate reduction"

Bijmans, M. F. M., C. J. N. Buisman, and Piet N. L. Lens. "Sulfate Reduction under Acidic Conditions in High Rate Bioreactor Systems for Treatment of Mining and Metallurgical Waste and Process Water." In Advanced Materials Research, 324–25. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-452-9.324.

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"Trichloroethylene biodegradation under sulfate reduction conditions." In Advanced Engineering and Technology, 209–14. CRC Press, 2014. http://dx.doi.org/10.1201/b16699-34.

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Wood, Robert J. K., and Mandar R. Thakare. "Abrasion-Corrosion of Thermal Spray Coatings." In Materials Science and Engineering, 1265–92. IGI Global, 2017. http://dx.doi.org/10.4018/978-1-5225-1798-6.ch050.

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WC-based thermal-spray and High Velocity Oxy-Fuel (HVOF) coatings are extensively used in a wide range of applications ranging from downhole drilling tools to gas turbine engines. WC-based thermal spray coatings offer improved wear resistance as a result of hard phases dispersed in binder-rich regions. However, the presence of hard and soft phases within the coating can also lead to the formation of micro-galvanic couplings in aqueous environments leading to some reduction in combined wear-corrosion resistance. Furthermore, the coating also responds differently to change in mechanical loading conditions. This chapter examines the wear-corrosion performance of thermal spray coatings in a range of wear, electrochemical, and wear-corrosion tests under varying contact conditions to develop models and establish relationships between wear mechanisms, wear rates, and environmental factors such as pH and applied load.

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Daniyal, Md, and Sabih Akhtar. "Corrosion Assessment and Control Techniques for Reinforced Concrete Structures." In New Challenges and Industrial Applications for Corrosion Prevention and Control, 226–59. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-2775-7.ch010.

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The steel reinforced concrete structures perform well in various environmental conditions, but structures may undergo premature damage in aggressive environments such as marine or acidic, primarily due to steel corrosion, and substantial reduction in service life occurs. This also causes huge economical loss and create safety and environmental problems. The repair and maintenance of steel reinforced concrete structures for their safety needs effective monitoring and inspection systems for evaluating the corrosion condition of steel. Since the corrosion of steel reinforcement occurs through electrochemical reactions, electrochemical methods are suitable to study the corrosion processes. In this chapter, some commonly used electrochemical techniques have been comprehensively explained. In addition, there is a critical requirement to develop effective and long-lasting techniques to control the corrosion of steel. Hence, some of the commonly used corrosion control methods have been comprehensively described in this chapter.

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Najiah Dahnel, Aishah, Mohamad Noor Ikhwan Naiman, Muhammad Azim Mirza Mohd Farid, Ahmad Faris Abdul Rahman, and Nur Munirah Meera Mydin. "Drilling of 7075 Aluminum Alloys." In Aluminium Alloys - Design and Development of Innovative Alloys, Manufacturing Processes and Applications [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.102864.

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Aluminum alloy (Al 7075) has been increasingly used as structural components in automotive and aerospace industry due to their low density, high strength and good corrosion resistance compared with other metals. To manufacture and assemble the components, drilling operations are often conducted. However, Al 7075 is ductile and soft, which causes difficulty in drilling, resulting in material adhesion, high tool wear, short tool life and poor hole quality. As a result of the poor hole quality, there is a high percentage of part rejection, which can increase the manufacturing time and cost. This chapter discusses challenges and techniques to drill Al 7075 in terms of the cutting parameters and drilling conditions to prolong the tool life and achieve good hole quality. Drilling experiments on Al 7075-T6 (heat-treated) were conducted using carbide cutting tools at various cutting parameters. Reducing cutting speed and increasing feed rate resulted in reducing tool wear, whereas a reduction in surface roughness, hence improved machined surface finish, was found when both cutting speed and feed rate were reduced in drilling Al 7075-T6. Producing good hole quality is vital during the drilling process to ensure a good assembly and product service performance.

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Su, Chunming, Robert W. Puls, Thomas A. Krug, Mark T. Watling, Suzanne K. O'Hara, Jacqueline W. Quinn, and Nancy E. Ruiz. "Long-Term Performance Evaluation of Groundwater Chlorinated Solvents Remediation Using Nanoscale Emulsified Zerovalent Iron at a Superfund Site." In Waste Management, 1352–71. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-1210-4.ch061.

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This chapter addresses a case study of long-term assessment of a field application of environmental nanotechnology. Dense Non-Aqueous Phase Liquid (DNAPL) contaminants such as Tetrachloroethene (PCE) and Trichloroethene (TCE) are a type of recalcitrant compounds commonly found at contaminated sites. Recent research has focused on their remediation using environmental nanotechnology in which nanomaterials such as nanoscale Emulsified Zerovalent Iron (EZVI) are added to the subsurface environment to enhance contaminant degradation. Such nanoremediation approach may be mostly applicable to the source zone where the contaminant mass is the greatest and source removal is a critical step in controlling the further spreading of the groundwater plume. Compared to micro-scale and granular counterparts, NZVI exhibits greater degradation rates due to its greater surface area and reactivity from its faster corrosion. While NZVI shows promise in both laboratory and field tests, limited information is available about the long-term effectiveness of nanoremediation because previous field tests are mostly less than two years. Here an update is provided for a six-year performance evaluation of EZVI for treating PCE and its daughter products at a Superfund site at Parris Island, South Carolina, USA. The field test consisted of two side-by-side treatment plots to remedy a shallow PCE source zone (less than 6 m below ground surface) using pneumatic injection and direct injection, separately in October 2006. For the pneumatic injections, a two-step injection procedure was used. First, the formation was fluidized by the injection of nitrogen gas alone, followed by injection of the EZVI with nitrogen gas as the carrier. In the pneumatic injection plot, 2,180 liters of EZVI containing 225 kg of iron (Toda RNIP-10DS), 856 kg of corn oil, and 22.5 kg of surfactant were injected to remedy an estimated 38 kg of chlorinated volatile compounds (CVOC)s. Direct injections were performed using a direct push rig. In the direct injection plot, 572 liters of EZVI were injected to treat an estimated 0.155 kg of CVOCs. Visual inspection of collected soil cores before and after EZVI injections shows that the travel distance of EZVI was dependent on the method of delivery with pneumatic injection achieving a greater distance of 2.1 m than did direct injection reaching a distance of 0.89 m. Significant decreases in PCE and TCE concentrations were observed in downgradient wells with corresponding increases in degradation products including significant increases in ethene. In the pneumatic injection plot, there were significant reductions in the downgradient groundwater mass flux values for chlorinated ethenes (>58%) and a significant increase in the mass flux of ethene (628%). There were significant reductions in total CVOCs mass (78%), which was less than an estimated 86% decrease in total CVOCs made at 2.5 years due to variations in soil cores collected for CVOCs extraction and determination; an estimated reduction of 23% (vs.63% at 2.5 years) in the sorbed and dissolved phases and 95% (vs. 93% at 2.5 years) reduction in the PCE DNAPL mass. Significant increases in dissolved sulfide, volatile fatty acids (VFA), and total organic carbon (TOC) were observed and dissolved sulfate and pH decreased in many monitoring wells. The apparent effective destruction of CVOC was accomplished by a combination of abiotic dechlorination by nanoiron and biological reductive dechlorination stimulated by the oil in the emulsion. No adverse effects of EZVI were observed for the microbes. In contrast, populations of dehalococcoides showed an increase up to 10,000 fold after EZVI injection. The dechlorination reactions were sustained for the six-year period from a single EZVI delivery. Repeated EZVI injections four to six years apart may be cost-effective to more completely remove the source zone contaminant mass. Overall, the advantages of the EZVI technology include an effective “one-two punch” of rapid abiotic dechlorination followed by a sustained biodegradation; contaminants are destroyed rather than transferred to another medium; ability to treat both DNAPL source zones and dissolved-phase contaminants to contain plume migration; ability to deliver reactants to targeted zones not readily accessible by conventional permeable reactive barriers; and potential for lower overall costs relative to alternative technologies such as groundwater pump-and-treat with high operation and maintenance costs or thermal technologies with high capital costs. The main limitations of the EZVI technology are difficulty in effectively distributing the viscous EZVI to all areas impacted with DNAPL; potential decrease in hydraulic conductivity due to iron corrosion products buildup or biofouling; potential to adversely impact secondary groundwater quality through mobilization of metals and production of sulfides or methane; injection of EZVI may displace DNAPL away from the injection point; and repeated injections may be required to completely destroy the contaminants.

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"gluten quality involves the addition of low levels of gluten, ied typically are compared to results obtained by some about 2%, to a standard test flour, which often is of a type of baking test. McDermott [85] compared baking "weak" type, and observing the effects on bread quality. (Chorleywood bake test) and other properties of 30 com-Water absorption is adjusted as appropriate for the gluten mercial glutens, mostly of European origin (Table 8), and levels added [23]. A stressed gluten-enriched baking test found that under his test conditions six samples were of was identified [31], which assumes that gluten is added to relatively poor quality; correlation between baking perfor-enable production of specialty breads using substantial mance and other measured properties was not high. levels of non-gluten-containing ingredients such as rye Weegels and Hamer [130] studied a group of 32 European flour, dietary fiber, bran and germ, or raisins [49]. Czucha-commercial glutens. These workers devised a test involv-j owska and Pomeranz [31] described a simple, repro-ing protein content, denaturation index (based on a series ducible method for baking undiluted gluten, highly corre-of sodium dodecyl sulfate sedimentation measurements), lated with the gluten-enrichment baking test. and extensigraph resistance; a model utilizing these tests A prime reason for performing end-use tests of func-was able to predict 59% of the baking quality variation of tionality, of course, is to monitor variations in the quality the glutens. Bushuk and Wadhawan [20] examined 27 of commercial wheat glutens that can occur. Differences commercial gluten samples, although only 8 were subject-among commercial gluten are usually attributable to varia-ed to extensive end-use testing; the highest correlation co-tions in the starting material, wheat or flour, and/or efficients were between loaf volume and acetic acid-solu-changes caused by production processing conditions. Dur-ble protein (r = 0.88) and between loaf volume and ing processing, the drying of gluten is critical, as noted fluorescence of acetic acid extract (r = 0.98). above, and investigators have shown that less than opti-mum heat treatment can lower the baking quality of gluten (b) Nonbaking Tests. Considerable efforts have been [14,49,98,111,130]. However, McDermott [85] reported expended in developing nonbaking tests to evaluate the no definite relationship between manufacturing variables quality or vitality of wheat gluten for baking purposes. The and gluten quality in a group of 30 commercial glutens. baking test is often cited as being labor intensive, relative-Dreese et al. [38] studied commercial and hand-washed ly expensive, requiring skilled workers, and not effectively lyophilized gluten and found that differences were more differentiating gluten quality [86]. The farinograph has attributable to washing procedures than to drying proce-been used to evaluate gluten for many years. The usual ap-dures. proach has been to test the gluten as a gluten-flour mixture Results obtained by other methods that have been stud-(e.g., Refs. 5, 18, 36, and 49), while an alternative method TABLE 8 Properties of 30 Commercial Glutens Baking performance Property Average Range Poor Average Good Increase in loaf volume, %a 10 7.7-12.2 8.3 10.2 11.8 Protein, %b 77.4 66.4-84.3 76.2 77.4 81.1 Moisture, % 7.55.3-10.2 8.877.7 Particle size, % <160 p.m 88.8 55.8-98 80.5 91 90.3 Color 68.3 56.5-75 65.2 68.9 69.5 Lipid, % 5.84.2-7.65.86.15.1 Ash, % 0.69 0.44-0.94 0.71 0.74 0.6 Chloride, %` 0.08 0.01-0.28 0.10.08 0.08 Water absorption, mug protein 2.37 1.84-2.93 2.26 2.45 2.29 SDS sedimentation volume, ml/g protein 99 55-159 70 107 127 Lactic acid sedimentation, % reduction in turbidity 18 2-68 49 11 7 Hydration time, min 0.90.2-10 2.72.40.6 Extensibility, units/min 3.80.7-9.33.23.93.9 Viscosity, cP 117 73-222 159 109 101 '2% gluten protein. Dry matter basis. `As NaCl. Source: Ref. 85." In Handbook of Cereal Science and Technology, Revised and Expanded, 779–92. CRC Press, 2000. http://dx.doi.org/10.1201/9781420027228-83.

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Тези доповідей конференцій з теми "Corrosion in the conditions of sulfate reduction"

Sharobem, Timothy T., and Marco J. Castaldi. "The Effect of SO2:HCl in Mixed Gas and Deposit Corrosion of Waste-to-Energy Boilers." In 2013 21st Annual North American Waste-to-Energy Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/nawtec21-2722.

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High temperature corrosion via chlorine is a key factor in the degradation of boiler tubes in waste-to-energy (WTE) plants. Corrosion rates are particularly high in the superheater where material temperatures may exceed 450°C and where carbon or low alloy steels may be used. Although increasing sulfur, in the form of SO2, in WTE flue gas has been shown in previous works to have potential for decreasing the corrosion of these materials, the inhibitive effect is not well understood. This work investigated the corrosion of SA178A, a low carbon steel alloy (0.07 wt% C), and NSSER-4, a stainless steel (17.3Cr-13.1Ni-2.5 Si-Fe), via exposure under various well-defined environments, SO2:HCl ratios between 1:8 to 2:1 (HCl fixed at 800 ppm), 8% O2, 12% CO2, 0 and 15% H2O, N2 (balance) at 500°C in a horizontal tube furnace for 50 hours. Additional coupon testing was performed on NSSER-4 after application of 4 mg/cm2 ± 10% NaCl or Na2SO4 at 500 and 700°C for 24 hours to assess the impact of higher SO2 in the against both deposit and gaseous corrosion. Specimen preparation and corrosion assessment followed ASTM method G1-03. Experiments demonstrated little to no trends in corrosion rates at SO2:HCl ratios between 1:8–2:1 under mixed gas environment. However corrosion reduction was observed when SO2:HCl was increased from a reference condition of 1:8 to greater than 1.4:1 in tests with NaCl present, which was also not observed under dry conditions. These results suggest that one possible explanation for the reduction of boiler materials corrosion rate with higher concentrations of SO2 may be largely attributed to the conversion of metal chlorides to sulfates.

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Wang, Lu, Amy T. Kan, Zhang Zhang, Fei Yan, Ya Liu, Zhaoyi Dai, and Mason B. Tomson. "Field Method for Determination of Bicarbonate Alkalinity." In SPE International Oilfield Scale Conference and Exhibition. SPE, 2014. http://dx.doi.org/10.2118/spe-169758-ms.

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Abstract Alkalinity is used to calculate the bicarbonate concentrations under various production conditions and the bicarbonate concentration is needed to calculate saturation indices for the prediction of carbonate and sulfide scale formation and also to predict the corrosivity of the produced water during production. Since the saturation index is related to the square of the bicarbonate concentration, the accuracy of alkalinity is vitally important for the prediction of corrosion and scaling indices of all oil and gas production systems. Unfortunately, the total alkalinity remains one of the most difficult parameters to be measured accurately in produced water due to both interferences and the difficulty in preserving the sample during storage. When collected samples de-gas during transport, the dissolved CO2 concentration decreases, pH increases, and brine components start to react with O2 and these reactions cause a reduction in bicarbonate alkalinity. In this study, an experimental method was developed to determine bicarbonate alkalinity in minimal time and operating difficulty. The apparatus consists of four parts: a low pressure sealing vessel, high accuracy pressure gauge, a syringe for acid addition and a thermometer. The changed pressure in this closed vessel, which indicates the amount of CO2 evolved after the addition of a strong acid, is used to determine the bicarbonate alkalinity of the sample. A wide range of synthetic waters and two production water samples were tested. Excellent agreement has been observed between true and calculated concentration. The results enable a more accurate measurement of produced water composition without the error caused by collection and preservation of samples. The field method combined with our automatic titration method enables more accurate prediction of pH, saturation index and corrosion risk at typical conditions of deep water production. This paper provides a reliable and detailed approach for field test of bicarbonate alkalinity with high accuracy and precision and a set of recommendations for field use.

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Tiemeyer, Amy E., Tara A. Kneeshaw, and Erin M. Driver. "USING MICROCOSMS TO EVALUATE IRON AND SULFATE REDUCTION RATES UNDER VARYING BIOGEOCHEMICAL CONDITIONS." In GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-301466.

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Shifler, David A. "The Increasing Complexity of Corrosion in Gas Turbines." In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90111.

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Abstract Removal of fuel sulfur assumes that hot corrosion events will subsequently end in shipboard and aero gas turbine engines. Most papers in the literature since the 1970s consider Na2SO4 and SO3 as the primary reactants causing hot corrosion. However, several geographical sites around the world have relatively high pollutant levels (particulate matter, SO2, etc.) that have the potential to initiate high-temperature corrosion. The deposit chemistry influencing hot corrosion is more complex consisting of multiple sulfates and silicates with the addition of chlorides in a marine environment. Sulfur species may still enter a ship combustion chamber as contaminants via air intake or with seawater entrained in air entering through the ship air intake. High levels of impurities (SO2) above 2 ppm can lead to hot corrosion attack. Research is needed to determine how sulfate salt mixtures and air impurities influence hot corrosion in marine and non-marine conditions. Other impurities such as phosphorus, lead, chlorides, sand, and unburned carbon may lower salt melting temperatures, alter the sulfate activity, or change the solution chemistry and acidity/basicity that leads to accelerating hot corrosion. Other issues need to be considered in non-metallic materials system.

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Men, Hong, Yan Peng, Jing Zhang, Shanrang Yang, and Zhiming Xu. "Study on Biocorrosion Induced by Sulfate-Reducing Bacteria on Heat Exchanger Material in Cooling Water." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22747.

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Corrosion associated with microorganisms has been recognized for over 50 years and yet the study of microbiologically influenced corrosion (MIC) is relatively new. MIC can occur in diverse environments. Industrial cooling water from rivers, lakes and sea water contain lots of microorganisms which are able to grow and multiply under certain conditions when pH, water temperature and sunlight etc are suitable. MIC is one of key cause of heat exchanger faults. MIC of heat exchanger materials in cooling waters has caused expensive unplanned outages, the need for local repairs and, in some cases, completes system replacement. Sulfate-reducing bacteria (SRB) are the main harmful bacteria in circulating cooling water. Under anaerobic conditions, SRB reproduce a lot to produce mucus, which speed up the formation of corrosion, erode the metal equipment, plug the pipeline, affect the efficiency of heat transfer, and bring a lot of inconvenience to the production. The corrosion behaviors of 304 stainless steel induced by SRB were studied by measuring the polarization curves, electrochemical impedance Spectrum, weight loss measurements of fore-and-aft biocorrosion, and electrochemical noise method. The electrochemical noise signal of 304 stainless steel corrosion were de-noised by using a wavelet threshold de-noising method, which made the quadratic biorthogonal spline wavelet as the mother wavelet and adopted an soft threshold processing function. The result showed that the slope of cathodic polarization curves measured included with SRB is lower than the one obtained without SRB, while the slope of anodic polarization curves is higher than it. It is concluded that the process of anode polarization was repressed at the presence of SRB. With the growth of the culture time, the value of electrochemical impedance without bacteria reduced at first, then rose, while with bacteria fell at all times. It indicated that SRB accelerated the corrosion of stainless steel. With the dipping time, a biofilm, under which corrosion products congregate to form local battery corrosion, was formed on the surface of stainless steel, so that the serious pitting corrosion is induced. The results from electrochemical noise method showed that the quadratic biorthogonal spline wavelet much smoother and it can remove the noise from the electrochemical noise effectively, and can effectively identify the location of the sudden changes in the signal and accurately reflect the useful information of the signal. The more useful information and data about biocorrosion induced by SRB are also gotten.

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Jeon, Chi-Ho, and Chang-Su Shim. "Experimental study on PSC beams with various conditions of corrosion." In IABSE Congress, Christchurch 2021: Resilient technologies for sustainable infrastructure. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2021. http://dx.doi.org/10.2749/christchurch.2021.0148.

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<p>There have been many reports released on failure of prestressing steels due to corrosion. This is taken seriously in that it can cause sudden collapse of the structure. In this paper, experimental investigation was performed to evaluate the performance of prestressed concrete beams. The strands of the specimens were electro-chemically corroded with Impressed Current Method (ICM). Location of corrosion, degree of corrosion, and the number of corroded strands are the parameters considered herein. The test result shows strength reduction of a centrally corroded PSC beam, but not in the other location near anchorages. Based on the analytical solutions using mechanical models of corroded strands with different pit depth, the flexural strength of the PSC beams was assessed. A procedure to assess the influence of the corroded strand on the behaviour of a PSC beam is suggested.</p>

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Miller, Jonathon D., Brett J. Warren, and Luc G. Chabot. "Microbiologically Influenced Corrosion of Gulf of Mexico Mooring Chain at 6,000 Feet Depths." In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-84067.

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During a post-installation inspection of a polyester and chain mooring system in water depths of approximately 6,000 ft, evidence of microbiologically influenced corrosion (MIC) was found in the form of rust tubercles known as rusticles. These porous concretions commonly form on submerged steel shipwrecks and provide evidence that subsea corrosion occurs in a hypoxic environment. Iron and sulfate-reducing bacteria cause corrosion in marine environments. This paper will discuss one form of MIC found on submerged steel structures, analyze the ambient conditions required for MIC to occur, and compare rusticles found during the mooring inspection to those found on other subsea shipwrecks such as the RMS Titanic. An analysis of the type of iron used in mooring chains and the rate of rusticle formation will be presented. Possible remedies to prevent rusticle growth on mooring chains will be summarized.

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Hannon, C. L., J. Gerstmann, F. B. Mansfeld, and Z. Sun. "Development of Corrosion Inhibitors for Absorption Heat Pumps." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-33411.

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This paper describes the results of a research project to develop a non-toxic corrosion in hibitor for the protection of carbon steel surfaces of ammonia-water absorption heat pumps through the use of rare earth metal salt (REMS) compounds. Chromate compounds are currently used as corrosion inhibitors in these systems, but are toxic, environmentally harmful, and their use is being phased out. Corrosion concerns in ammonia-water absorption systems are primarily those of non-condensable (NC) gases generated by corrosion reactions impeding the heat and mass transfer processes in the system. The research focused on the development of a dual-protection REMS based strategy of applying a cerium-oxide/hydroxide coating to the metal surface in a process called cerating, in conjunction with a cerium-sulfate solution-based inhibitor. A laboratory test was conducted in test rigs designed to simulate the conditions of temperature and ammonia concentration found in the desorber component of advanced ammonia-water absorption systems. The test compared the NC gas generation rate in a rig with cerated steel surfaces to a rig using sodium chromate as a solution based inhibitor. The cerated test rig demonstrated an NC gas generation rate about 3 times lower than that of the chromate protected rig. Neither rig showed any indications of significant corrosion activity. This work has shown that cerating can provide superior suppression of NC gas generation in ammonia-water absorption systems compared to sodium chromate, in a process that is simple and readily applicable to the commercial manufacture of equipment.

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Vega, Oscar E., Jose´ M. Hallen, Agusti´n Villagomez, and Antonio Contreras. "Microstructure, Mechanical Properties and SSC Susceptibility of Multiple SMAW Repairs in Line Pipe Girth Welds." In 2008 7th International Pipeline Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ipc2008-64187.

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Girth welds of seamless API X52 steel pipe containing multiple shielded metal arc welding (SMAW) repairs and one as-welded condition were studied. Microstructural characterization, mechanical behavior and sulfide stress corrosion cracking (SSC) susceptibility of the welded joints were evaluated by means of optical and scanning electron microscopy, hardness, tension, Charpy-V impact resistance and slow strain rate tests (SSRT). The results of this work indicate that increasing the number of welding repairs promotes grain growth in the heat affected zone (HAZ). The yield strength (YS) and ultimate tensile strength (UTS) for the different welding repairs satisfy the specified minimum values of the material. Significant reduction in Charpy-V impact resistance with the increases of the number of repairs was found in the coarse grained heat affected zone (CGHAZ). A high susceptibility to SSC was exhibited by the welded joints and the intercritical heat affected zone was the most susceptible area to SSC.

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Ferrari, Jean Vicente. "Discussion of Oxygen Threshold Level for Corrosion Management in Seawater Injection Systems." In SPE International Oilfield Corrosion Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/205041-ms.

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Abstract Generally, in water injection systems, oxygen levels starting from around eight ppm are deoxygenated to below 50 ppm, following international standards' guidelines. This work aims to discuss the impact of such a magnitude value of oxygen contamination on steel corrosion in seawater injection systems by analysing theoretical polarisation curves and results from published works with different approaches. Corrosion models consider mass-transfer controlled diffusion of oxygen to predict the maximum steel corrosion rate, which depends on the oxygen limiting current, which in turn is strongly influenced by flow velocity. The effect of free chlorine on corrosion in seawater injection systems has also been considered and included in an oxygen equivalent parameter. In such systems, where oxygen reduction is the key cathodic reaction, the corrosion process may be under cathodic activation control, independent of flow at higher velocities or when erosion-corrosion begins. In this work, theoretical polarisation curves were constructed by using published oxygen and chlorine cathodic limiting currents (iLc) on carbon steel and a noble metal electrode, respectively. Aerated (200 ppb and 9000 ppb of oxygen) and deaerated conditions (50 ppb of oxygen) and the presence of 300 ppb of chlorine were applied to the assumed exchange current densities (io). Neutral (pH 7) and acid (pH 4) conditions (considering the presence of CO2) were also assumed to be at room temperature and pressure. Since the corrosion rate in lower oxygen concentrations (ppb order of magnitude) may result in corrosion rates of the same order of magnitude than in higher oxygen concentrations (ppm order of magnitude) when comparing and analysing results from experimental, semi-empirical or mechanistic approaches, it is necessary to weigh up the effects of both steel surface (bare or scaled/corrosion products) and flow. At oxygen concentrations below 200 ppb and under acid conditions, the contribution of H+ reduction on corrosion rate starts to be higher than oxygen reduction, mainly in the absence of chlorine.

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Звіти організацій з теми "Corrosion in the conditions of sulfate reduction"

Kingston, A. W., O. H. Ardakani, and R A Stern. Tracing the subsurface sulfur cycle using isotopic and elemental fingerprinting: from the micro to the macro scale. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/329789.

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Анотація:

Hydrogen sulfide (H2S) is a toxic and corrosive gas that commonly occurs in deeply buried sedimentary systems. Understanding its distribution is paramount to creating safe and effective models of H2S occurrence aiding in the identification of high-risk areas. Characterizing subsurface sulfur sources and H2S formation pathways would enhance these models leading to more accurate predictions of potential high H2S regions. However, gaps remain in our understanding of the dominant formation processes and migration pathways of key ingredients for H2S production in the Lower Triassic Montney Formation of the Western Canada Sedimentary Basin (WCSB). Essential to this is assessing the reactants necessary for H2S production, potential pathways for fluid migration, diagenetic history, and changes in redox conditions through time. The Montney Formation has undergone several phases of diagenesis related to post-depositional alteration and multiple cycles of tectonic burial and uplift. Early chemical alteration includes dolomitization and, in some cases, microbial reduction of porewater sulfate to sulfide that occurred prior to significant burial (Davies et al., 1997; Vaisblat et al., 2021; Liseroudi et al., 2020, 2021). The most recent tectonic-related burial during the Laramide Orogeny resulted in burial depths in excess of 3-5 km (Ness, 2001; Ducros et al., 2017) leading to significant thermal and barometric alteration. Associated with this orogenic activity was the reactivation of underlying faults (O'Connell et al., 1990) and development of fractures especially near the deformation front. These fractures provide conduits for fluid migration into the Montney that combined with heat and pressure resulting in hydrocarbon generation, migration, and development of overpressure, notably in the western margin of the basin. In addition, high temperatures resulted in thermochemical sulfate reduction (TSR) leading to the formation of H2S and subsequently pyrite. We present an interpretation of the Montney subsurface sulfur cycle through the use of petrography, micro- and macro-scale geochemical analysis (isotopic and elemental) to illustrate the complexity of this system. This work relies heavily on previous studies within and outside our research group and incorporates new analytical techniques to expand the toolbox. We aim to guide future research directions and activities by addressing issues related to sampling and data quality issues, analytical approaches, and highlight knowledge gaps.

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