Pub Date : 2001-10-01DOI: 10.1179/000705901101501703
M. Abdel-Aal, M. Morad
Abstract The inhibiting effects of quinoline, 8-hydroxyquinoline, benzo(f)quinoline, quinoline-2-thiol, triphenylbenzyl, and tetrabenzyl phosphonium chloride on the corrosion of mild steel (0.26 wt-%C) in deaerated 3M HCl solution have been studied using the determination of polarisation curves as well as linear polarisation measurements. Adsorption isotherms and thermodynamic parameters for the adsorption process of the inhibitors were also determined and are discussed. Except for benzo(f)quinoline, which acts as an accelerator of corrosion, the other quinolines act as corrosion inhibitors. The inhibition was found to be predominantly anodic with quinoline and 8-hydroxyquinoline, while quinoline-2-thiol is a mixed inhibitor. The increase in inhibition efficiency with temperature, the resulting Langmuir adsorption isotherm and the high negative values of the standard free energy of adsorption ΔGa° denoted chemisorption. Triphenylbenzyl and tetrabenzyl phosphonium compounds were found to be inhibitors of the mixed type. High negative values of the standard free energy of adsorption and the resulting Temkin isotherm indicated chemisorption of the phosphonium compounds. The positive values of the standard enthalpy and entropy of adsorption indicated that adsorption of the inhibitors is associated with the desorption of H2O molecules from the electrode surface. High values of the standard energy of activation Ea* of the inhibited corrosion process were interpreted in terms of deactivating coverage.
{"title":"Inhibiting effects of some quinolines and organic phosphonium compounds on corrosion of mild steel in 3M HCl solution and their adsorption characteristics","authors":"M. Abdel-Aal, M. Morad","doi":"10.1179/000705901101501703","DOIUrl":"https://doi.org/10.1179/000705901101501703","url":null,"abstract":"Abstract The inhibiting effects of quinoline, 8-hydroxyquinoline, benzo(f)quinoline, quinoline-2-thiol, triphenylbenzyl, and tetrabenzyl phosphonium chloride on the corrosion of mild steel (0.26 wt-%C) in deaerated 3M HCl solution have been studied using the determination of polarisation curves as well as linear polarisation measurements. Adsorption isotherms and thermodynamic parameters for the adsorption process of the inhibitors were also determined and are discussed. Except for benzo(f)quinoline, which acts as an accelerator of corrosion, the other quinolines act as corrosion inhibitors. The inhibition was found to be predominantly anodic with quinoline and 8-hydroxyquinoline, while quinoline-2-thiol is a mixed inhibitor. The increase in inhibition efficiency with temperature, the resulting Langmuir adsorption isotherm and the high negative values of the standard free energy of adsorption ΔGa° denoted chemisorption. Triphenylbenzyl and tetrabenzyl phosphonium compounds were found to be inhibitors of the mixed type. High negative values of the standard free energy of adsorption and the resulting Temkin isotherm indicated chemisorption of the phosphonium compounds. The positive values of the standard enthalpy and entropy of adsorption indicated that adsorption of the inhibitors is associated with the desorption of H2O molecules from the electrode surface. High values of the standard energy of activation Ea* of the inhibited corrosion process were interpreted in terms of deactivating coverage.","PeriodicalId":9349,"journal":{"name":"British Corrosion Journal","volume":"22 1","pages":"253 - 260"},"PeriodicalIF":0.0,"publicationDate":"2001-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85622267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-10-01DOI: 10.1179/000705901101501712
S. Keera
Abstract The corrosion of low carbon steel in mixtures of oil and water with various oil/water ratios has been studied using weight loss and potentiodynamic polarisation measurements. The inhibiting behaviour of some alkyl amine ethoxylate derivatives having an average of 14-14.3 moles ethylene oxide per mole and different chain lengths has been investigated. These included: ethoxylated hexyl amine, C6H13NH(CH2CH2O)14-H; ethoxylated decyl amine, C6 0H13NH(CH2CH2O)14-H; and ethoxylated tetradecyl amine, C14H29NH(CH2CH2O)14-H. The inhibitors were used at concentrations corresponding to 40-100 ppm of the water content in the environment and the effects of storage time at temperatures of 30, 50, and 70 °C were investigated. The inhibitors provided satisfactory corrosion inhibition which decreased with increasing temperature. The adsorption of the inhibitors on the carbon steel surface was found to obey the Langmiur adsorption isotherm. Thermodynamic activation parameters such as the activation energy E°, enthalpy ΔH°, entropy ΔS°, and free energy of activation ΔG° for the dissolution of carbon steel were calculated. The inhibition efficiency was observed to increase with increasing chain length of the alkyl amine group. The tetradecyl amine ethoxylate, which has the longest chain, was the most efficient inhibitor.
{"title":"Inhibition of steel by alkylamine ethoxylate in petroleum production","authors":"S. Keera","doi":"10.1179/000705901101501712","DOIUrl":"https://doi.org/10.1179/000705901101501712","url":null,"abstract":"Abstract The corrosion of low carbon steel in mixtures of oil and water with various oil/water ratios has been studied using weight loss and potentiodynamic polarisation measurements. The inhibiting behaviour of some alkyl amine ethoxylate derivatives having an average of 14-14.3 moles ethylene oxide per mole and different chain lengths has been investigated. These included: ethoxylated hexyl amine, C6H13NH(CH2CH2O)14-H; ethoxylated decyl amine, C6 0H13NH(CH2CH2O)14-H; and ethoxylated tetradecyl amine, C14H29NH(CH2CH2O)14-H. The inhibitors were used at concentrations corresponding to 40-100 ppm of the water content in the environment and the effects of storage time at temperatures of 30, 50, and 70 °C were investigated. The inhibitors provided satisfactory corrosion inhibition which decreased with increasing temperature. The adsorption of the inhibitors on the carbon steel surface was found to obey the Langmiur adsorption isotherm. Thermodynamic activation parameters such as the activation energy E°, enthalpy ΔH°, entropy ΔS°, and free energy of activation ΔG° for the dissolution of carbon steel were calculated. The inhibition efficiency was observed to increase with increasing chain length of the alkyl amine group. The tetradecyl amine ethoxylate, which has the longest chain, was the most efficient inhibitor.","PeriodicalId":9349,"journal":{"name":"British Corrosion Journal","volume":"32 1","pages":"261 - 265"},"PeriodicalIF":0.0,"publicationDate":"2001-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91355178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-10-01DOI: 10.1179/bcj.1996.31.2.98
L. Gittins, J. Costa, R. W. Lewis, A. Patsis, J. Gibson, J. Chenoweth
{"title":"Forthcoming corrosion events","authors":"L. Gittins, J. Costa, R. W. Lewis, A. Patsis, J. Gibson, J. Chenoweth","doi":"10.1179/bcj.1996.31.2.98","DOIUrl":"https://doi.org/10.1179/bcj.1996.31.2.98","url":null,"abstract":"","PeriodicalId":9349,"journal":{"name":"British Corrosion Journal","volume":"20 1","pages":"236 - 239"},"PeriodicalIF":0.0,"publicationDate":"2001-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73528535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-10-01DOI: 10.1179/000705901101501730
C. P. Gardiner, R. Melchers
Abstract The process of enclosed atmospheric corrosion within ship spaces is investigated. It is proposed that corrosion rates are influenced mainly by three parameters; time of wetness, salt deposition and temperature. Assuming atmospheric corrosion to be primarily cathodically controlled, it is shown that, as a first approximation, the rate of atmospheric corrosion is linearly proportional to both temperature and salt deposition. This is shown to be consistent with available experimental data. An equation is presented for the prediction of corrosion rates within ship spaces exposed to an enclosed atmosphere, such as cargo holds and ballast tanks, on a per voyage basis. The influencing parameters identified in this study, and the proposed model, provide a starting point for future probabilistic modelling of one component of ship corrosion, namely, enclosed atmospheric corrosion.
{"title":"Enclosed atmospheric corrosion in ship spaces","authors":"C. P. Gardiner, R. Melchers","doi":"10.1179/000705901101501730","DOIUrl":"https://doi.org/10.1179/000705901101501730","url":null,"abstract":"Abstract The process of enclosed atmospheric corrosion within ship spaces is investigated. It is proposed that corrosion rates are influenced mainly by three parameters; time of wetness, salt deposition and temperature. Assuming atmospheric corrosion to be primarily cathodically controlled, it is shown that, as a first approximation, the rate of atmospheric corrosion is linearly proportional to both temperature and salt deposition. This is shown to be consistent with available experimental data. An equation is presented for the prediction of corrosion rates within ship spaces exposed to an enclosed atmosphere, such as cargo holds and ballast tanks, on a per voyage basis. The influencing parameters identified in this study, and the proposed model, provide a starting point for future probabilistic modelling of one component of ship corrosion, namely, enclosed atmospheric corrosion.","PeriodicalId":9349,"journal":{"name":"British Corrosion Journal","volume":"80 1","pages":"272 - 276"},"PeriodicalIF":0.0,"publicationDate":"2001-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80423531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-10-01DOI: 10.1179/000705901101501622
A. Iversen
Abstract Microbially influenced corrosion (MIC)on stainless steel in freshwater is commonly related to the development of an active biofilm on the surface. A known effect of the microbial activity that causes the formation of a biofilm on stainless steel surfaces is the ennoblement of the stainless steel, as shown in the field test presented in part 1 of this study. Ennoblement may increase the risk of local corrosion if the potential rises above the breakdown potential of the passive layer for the steel grade. An aim of this investigation was to examine the reasons for corrosion when ennoblement occurs on stainless steels and to provide guidance on the use of particular grades of stainless steel in the final stages of waste water treatment systems operating under aerobic conditions. In this paper (part 2), the corrosion resistance of stainless steels in distilled waters containing various amounts of chlorides, nitrates, and sulphates has been evaluated according to a factorial design. A risk window was then designed for predicting MIC on stainless steel in aerobic waste water treatment plants based on these results. Another aim of the investigation, carried out in a waste water treatment plant, was to test coupons with residual weld oxides on the surface and to compare the corrosion resistance with pickled welded coupons. All coupons were exposed in the final stage of the plant where no ennoblement of the open circuit potential occurred in the beginning. Nevertheless, after several weeks, high potentials were recorded following heavy rainfall. After field test, visual inspection revealed corrosion on AISI 304 stainless steel.
{"title":"Microbially influenced corrosion on stainless steel in waste water treatment plants: Part 2","authors":"A. Iversen","doi":"10.1179/000705901101501622","DOIUrl":"https://doi.org/10.1179/000705901101501622","url":null,"abstract":"Abstract Microbially influenced corrosion (MIC)on stainless steel in freshwater is commonly related to the development of an active biofilm on the surface. A known effect of the microbial activity that causes the formation of a biofilm on stainless steel surfaces is the ennoblement of the stainless steel, as shown in the field test presented in part 1 of this study. Ennoblement may increase the risk of local corrosion if the potential rises above the breakdown potential of the passive layer for the steel grade. An aim of this investigation was to examine the reasons for corrosion when ennoblement occurs on stainless steels and to provide guidance on the use of particular grades of stainless steel in the final stages of waste water treatment systems operating under aerobic conditions. In this paper (part 2), the corrosion resistance of stainless steels in distilled waters containing various amounts of chlorides, nitrates, and sulphates has been evaluated according to a factorial design. A risk window was then designed for predicting MIC on stainless steel in aerobic waste water treatment plants based on these results. Another aim of the investigation, carried out in a waste water treatment plant, was to test coupons with residual weld oxides on the surface and to compare the corrosion resistance with pickled welded coupons. All coupons were exposed in the final stage of the plant where no ennoblement of the open circuit potential occurred in the beginning. Nevertheless, after several weeks, high potentials were recorded following heavy rainfall. After field test, visual inspection revealed corrosion on AISI 304 stainless steel.","PeriodicalId":9349,"journal":{"name":"British Corrosion Journal","volume":"332 1","pages":"284 - 291"},"PeriodicalIF":0.0,"publicationDate":"2001-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77789682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-10-01DOI: 10.1179/000705901101501721
J. J. Santana, J. Santana, J. E. González, D. de la Fuente, B. Chico, M. Morcillo
Abstract On small islands like the Canary Isles the atmospheric corrosion of metals is a major concern, especially for the electricity and building industries. Corrosivity maps provide a helpful tool for selecting suitable materials, protection systems, maintenance intervals, etc. In this work an atmospheric corrosivity map for steel has been developed in the eastern zone of the Canary Isles archipelago following ISO standard 9223. The proposed map is based on corrosion rate results measured at 39 test sites located across the zone's three main islands: Gran Canaria, Fuerteventura, and Lanzarote. The study has also considered the influence of atmospheric salinity, and its dependence on distance from the sea and marine winds, on the atmospheric corrosion of steel.
{"title":"Atmospheric corrosivity map for steel in Canary Isles","authors":"J. J. Santana, J. Santana, J. E. González, D. de la Fuente, B. Chico, M. Morcillo","doi":"10.1179/000705901101501721","DOIUrl":"https://doi.org/10.1179/000705901101501721","url":null,"abstract":"Abstract On small islands like the Canary Isles the atmospheric corrosion of metals is a major concern, especially for the electricity and building industries. Corrosivity maps provide a helpful tool for selecting suitable materials, protection systems, maintenance intervals, etc. In this work an atmospheric corrosivity map for steel has been developed in the eastern zone of the Canary Isles archipelago following ISO standard 9223. The proposed map is based on corrosion rate results measured at 39 test sites located across the zone's three main islands: Gran Canaria, Fuerteventura, and Lanzarote. The study has also considered the influence of atmospheric salinity, and its dependence on distance from the sea and marine winds, on the atmospheric corrosion of steel.","PeriodicalId":9349,"journal":{"name":"British Corrosion Journal","volume":"55 1","pages":"266 - 271"},"PeriodicalIF":0.0,"publicationDate":"2001-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81209845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-10-01DOI: 10.1179/000705901101501749
A. Iversen
Abstract Field tests on stainless steels have been carried out at five waste water treatment plants for one year. Three grades of stainless steel, i.e. AISI 304 (UNS S30400), AISI 316 (UNS S31600), and duplex 2205 (UNS S31803) were tested in the final settling tank in the plants. The time dependence of the open circuit potential (OCP) was measured for all coupons. Ennoblement of the OCP, similar to that reported from investigations in sea water, was found in one of the plants. Waters from three of the exposure sites, containing dispersed deposits from exposed coupons, were chemically analysed. Pitting corrosion was observed after the field test on steel grade AISI 304 in three of the five plants, and on AISI 316 in one plant. No corrosion was found on 2205 in any of the plants. Laboratory measurements of the OCP were carried out for the AISI 304, AISI 316, and duplex 2205 steels in water collected from one of the plants. Cathodic polarisation curves were recorded in waste water from the same plant. T he cathodic reaction rate increased at the highest OCP. Simulation of the ennoblement was carried out by potentiostatic polarisation in a 600 ppm chloride solution. The current response indicated corrosion of welded AISI 304 material and of AISI 304 and AISI 316 steels in crevice assemblies after a long induction time. Part 2 of this study presents the results of further testing and a risk assessment design.
{"title":"Microbially influenced corrosion on stainless steels in waste water treatment plants: Part 1","authors":"A. Iversen","doi":"10.1179/000705901101501749","DOIUrl":"https://doi.org/10.1179/000705901101501749","url":null,"abstract":"Abstract Field tests on stainless steels have been carried out at five waste water treatment plants for one year. Three grades of stainless steel, i.e. AISI 304 (UNS S30400), AISI 316 (UNS S31600), and duplex 2205 (UNS S31803) were tested in the final settling tank in the plants. The time dependence of the open circuit potential (OCP) was measured for all coupons. Ennoblement of the OCP, similar to that reported from investigations in sea water, was found in one of the plants. Waters from three of the exposure sites, containing dispersed deposits from exposed coupons, were chemically analysed. Pitting corrosion was observed after the field test on steel grade AISI 304 in three of the five plants, and on AISI 316 in one plant. No corrosion was found on 2205 in any of the plants. Laboratory measurements of the OCP were carried out for the AISI 304, AISI 316, and duplex 2205 steels in water collected from one of the plants. Cathodic polarisation curves were recorded in waste water from the same plant. T he cathodic reaction rate increased at the highest OCP. Simulation of the ennoblement was carried out by potentiostatic polarisation in a 600 ppm chloride solution. The current response indicated corrosion of welded AISI 304 material and of AISI 304 and AISI 316 steels in crevice assemblies after a long induction time. Part 2 of this study presents the results of further testing and a risk assessment design.","PeriodicalId":9349,"journal":{"name":"British Corrosion Journal","volume":"12 1","pages":"277 - 283"},"PeriodicalIF":0.0,"publicationDate":"2001-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80972981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-10-01DOI: 10.1179/000705901101501668
B. Hou, J. Zhang, H.-Y. Sun, Yongxiang Li, B. Xiang
Abstract Experiments to simulate the corrosion of a mild steel (designated A3) in the open sea have been conducted to explain observed differences between the behaviour of suspended specimens that were electrically connected together on the one hand and unconnected on the other. Reasons for differences between the corrosion behaviour of individually suspended specimens in the laboratory and that of steel in a marine service environment have also been investigated. The effect on corrosion of the ratio of water depth in the tidal zone to that in the immersion zone has also been studied.
{"title":"Corrosion of C–Mn steel in simulated tidal and immersion zones","authors":"B. Hou, J. Zhang, H.-Y. Sun, Yongxiang Li, B. Xiang","doi":"10.1179/000705901101501668","DOIUrl":"https://doi.org/10.1179/000705901101501668","url":null,"abstract":"Abstract Experiments to simulate the corrosion of a mild steel (designated A3) in the open sea have been conducted to explain observed differences between the behaviour of suspended specimens that were electrically connected together on the one hand and unconnected on the other. Reasons for differences between the corrosion behaviour of individually suspended specimens in the laboratory and that of steel in a marine service environment have also been investigated. The effect on corrosion of the ratio of water depth in the tidal zone to that in the immersion zone has also been studied.","PeriodicalId":9349,"journal":{"name":"British Corrosion Journal","volume":"6 1","pages":"310 - 312"},"PeriodicalIF":0.0,"publicationDate":"2001-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74355930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-10-01DOI: 10.1179/000705901101501631
C. Angeles-Chávez, J. M. Romero, M. Amaya, L. Martínez, R. Pérez
Abstract Studies of microbiologically induced corrosion have been carried out in connection with sea water pipelines used in the oil fields of the Southern Region of Mexico. The bacteria used in the studies were obtained from a sea water pipeline belonging to a secondary oil recovery system and were grown in an API RP 38 liquid medium. The morphological and chemical characteristics of the bacteria isolated from the growth medium were investigated and phylogenetic analysis showed that the most closely related bacterial strain is clostridium sphenoides. However, the existence of significant differences in the phylogenetic codes indicates that the bacteria from the sea water pipeline belongs to a new species of sulphate reducing bacteria. Coupons of API 5L X52 pipeline steel exposed to these bacteria developed corrosion pits which did not form during the exposure of similar coupons to the sterile growth medium. What is more, bacteria from the biofilm formed on the pitted coupons contained iron, which was absent from bacteria cultured in growth medium in which there were no steel coupons. These results demonstrate the existence of an association between the new species of sulphate reducing bacteria and the development of pitting corrosion in X52 pipeline steel.
摘要对墨西哥南部地区油田使用的海水管道进行了微生物腐蚀研究。研究中使用的细菌是从属于二次采油系统的海水管道中获得的，并在API RP 38液体培养基中生长。对从培养基中分离的细菌进行了形态和化学特征的研究，系统发育分析表明，与之亲缘关系最密切的菌株是蝶形梭状芽胞杆菌。然而，系统发育密码的显著差异表明，来自海水管道的细菌属于一种新的硫酸盐还原细菌。暴露在这些细菌下的API 5L X52管线钢试样产生了腐蚀坑，而类似试样暴露在无菌培养基中不会形成腐蚀坑。更重要的是，在凹痕钢板上形成的生物膜中的细菌含有铁，而在没有钢钢板的培养基中培养的细菌则不含铁。这些结果表明，新型硫酸盐还原菌的出现与X52管线钢的点蚀有一定的关系。
{"title":"New strain of anaerobic bacteria and its association with corrosion pitting of X52 pipeline steel","authors":"C. Angeles-Chávez, J. M. Romero, M. Amaya, L. Martínez, R. Pérez","doi":"10.1179/000705901101501631","DOIUrl":"https://doi.org/10.1179/000705901101501631","url":null,"abstract":"Abstract Studies of microbiologically induced corrosion have been carried out in connection with sea water pipelines used in the oil fields of the Southern Region of Mexico. The bacteria used in the studies were obtained from a sea water pipeline belonging to a secondary oil recovery system and were grown in an API RP 38 liquid medium. The morphological and chemical characteristics of the bacteria isolated from the growth medium were investigated and phylogenetic analysis showed that the most closely related bacterial strain is clostridium sphenoides. However, the existence of significant differences in the phylogenetic codes indicates that the bacteria from the sea water pipeline belongs to a new species of sulphate reducing bacteria. Coupons of API 5L X52 pipeline steel exposed to these bacteria developed corrosion pits which did not form during the exposure of similar coupons to the sterile growth medium. What is more, bacteria from the biofilm formed on the pitted coupons contained iron, which was absent from bacteria cultured in growth medium in which there were no steel coupons. These results demonstrate the existence of an association between the new species of sulphate reducing bacteria and the development of pitting corrosion in X52 pipeline steel.","PeriodicalId":9349,"journal":{"name":"British Corrosion Journal","volume":"64 1","pages":"292 - 296"},"PeriodicalIF":0.0,"publicationDate":"2001-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73906614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-10-01DOI: 10.1179/000705901101501659
G. Madhusudhan Reddy, A. Gokhale, N. Narendra Janaki Ram, K. Prasad Rao
Abstract The effects of changing the welding technique on the weld bead solidification structure and resistance to pitting corrosion of an aeronautical grade Al-Li based alloy have been studied. Russian alloy 1441, with a nominal composition Al-1.9Li-1.8Cu-1.0Mg-0.1Zr (wt-%) and in the form of sheet, was welded using constant current, pulsed current and arc oscillation gas tungsten arc welding techniques. Under the optimum conditions of welding, the solidification structure was coarse columnar in constant current welds, fine equiaxed in pulsed current welds and fine equiaxed intermixed with fine cellular grains in arc oscillation welds. The distribution of interdendritic (and intergranular) non-equilibrium solidification products became increasing discrete on changing from constant current to pulsed current and arc oscillation welding. Resitance to pitting corrosion was found to be greatest in welds having a discrete second phase distribution, i.e. those produced using the pulsed current and arc oscillation methods.
{"title":"Influence of welding techniques on microstructure and pitting corrosion behaviour of 1441 grade Al–Li alloy gas tungsten arc welds","authors":"G. Madhusudhan Reddy, A. Gokhale, N. Narendra Janaki Ram, K. Prasad Rao","doi":"10.1179/000705901101501659","DOIUrl":"https://doi.org/10.1179/000705901101501659","url":null,"abstract":"Abstract The effects of changing the welding technique on the weld bead solidification structure and resistance to pitting corrosion of an aeronautical grade Al-Li based alloy have been studied. Russian alloy 1441, with a nominal composition Al-1.9Li-1.8Cu-1.0Mg-0.1Zr (wt-%) and in the form of sheet, was welded using constant current, pulsed current and arc oscillation gas tungsten arc welding techniques. Under the optimum conditions of welding, the solidification structure was coarse columnar in constant current welds, fine equiaxed in pulsed current welds and fine equiaxed intermixed with fine cellular grains in arc oscillation welds. The distribution of interdendritic (and intergranular) non-equilibrium solidification products became increasing discrete on changing from constant current to pulsed current and arc oscillation welding. Resitance to pitting corrosion was found to be greatest in welds having a discrete second phase distribution, i.e. those produced using the pulsed current and arc oscillation methods.","PeriodicalId":9349,"journal":{"name":"British Corrosion Journal","volume":"115 1","pages":"304 - 309"},"PeriodicalIF":0.0,"publicationDate":"2001-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78723080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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