Effects of turbulent flow on the corrosion kinetics of X52 pipeline steel in aqueous solutions containing H2S

This work presents the electrochemical results obtained during the study of the corrosion of X52 pipeline steel sample, immersed in brines containing H₂S, under turbulent flow conditions. Linear polarisation resistance (LPR), electrochemical impedance spectroscopy (EIS), Electrochemical Noise (EN) and polarisation curves were used in order to determine the effect of turbulent flow upon the corrosion kinetics of the steel. It was found that flow has a considerable influence upon the electrochemical process occurring on the surface of the steel and the corrosion rate is increased.     

油气管线钢土壤环境硫酸盐还原菌腐蚀研究进展

结合国内外埋地管线钢微生物腐蚀的研究,综述了腐蚀性土壤微生物种类和特点、环境因素对硫酸盐还原菌腐蚀的影响、生物腐蚀研究方法和进展,以及微生物腐蚀防护与监检测技术.最后,对埋地管线钢微生物腐蚀研究进行了展望.埋地管线钢服役环境复杂,受到土壤类型、杂散电流、阴极保护、应力、剥离涂层和微生物等多种因素的影响,而各种因素之间又存在着相互的耦合作用.多因素耦合作用下埋地管线钢微生物腐蚀将成为土壤微生物腐蚀今后的主要研究方向.土壤微生物腐蚀研究涉及土壤学、材料学、腐蚀科学和微生物学等多学科,是一个多学科交叉的研究课题,而化学和电化学分析技术、微生物分析技术以及材料表征技术等的联用也将为土壤微生物腐蚀行为和机制的研究提供更多的研究方法,这也有助于更好地理解微生物/材料之间的相互作用机制.随着对微生物腐蚀研究的深入,人们对硫酸盐还原菌腐蚀机理的认识也更加全面,"生物阴极催化还原"理论从生物能量学和生物电化学角度解释了微生物腐蚀的过程和机理.抗菌涂层开发和耐微生物腐蚀管线钢研发为MIC防治提供了一个新的研究路径.     

Microbial consortium influence upon steel corrosion rate,using the electrochemical impedance spectroscopy technique

The Electrochemical Impedance Technique was used to evaluate the influence of a microbial consortium, isolated from a gas pipeline, upon API XL52 steel corrosion rate. The bacteria growth exhibited two different kinetics behavior, one for the plancktonic and the other for the sessile phase. The sessile bacteria were found to be the main responsible for the corrosion rate increment observed during the experiments and no relationship between the plancktonic microorganisms and the corrosion rate increment was found. The diagrams obtained from the electrochemical impedance measurements, indicated a biofilm formation and that the system changed from activation to diffusion control. Although the system was under diffusion control, an increment on the corrosion rate was detected, and a localized corrosion process was induced. The results were complemented with some surface analysis using Scanning Electron Microscopy.     

Role of anaerobic and aerobic bacteria in localised corrosion: field and laboratory morphological study

Abstract

Bacterial evidence was found in the biofilm deposited on the surface of an API X52 steel coupon following exposure to flowing seawater within a pipeline for 60 days. Extensive corrosion pitting was observed on the steel surface after removing the biofilm. Several types of anaerobic and aerobic bacteria were isolated from the biofilm. The anaerobic bacteria were cultured and grown in API RP 38 culture medium and the aerobic bacteria were grown in a general heterotrophic culture medium. The morphological and chemical characteristics of the bacteria were determined. Subsequently, separate specimens of API X52 pipeline steel were inoculated with each bacterial strain in under laboratory conditions. The specimen exposed to the anaerobic bacteria showed several micropits of different sizes on its surface while that exposed to the aerobic bacteria showed freedom from surface pits.     

Enhanced Bio-corrosion Resistance by Cu Alloying in a Micro-alloyed Pipeline Steel

On the composition base of commercial X65 grade pipeline steels, a Cu modified pipeline steel was designed to show improved resistance to microbially induced corrosion (MIC). The mechanical properties of the Cu-added steel and its corrosion behavior in a soil solution inoculated with sulfate-reducing bacteria (SRB) were investigated in this work. The results demonstrated that Cu-added steel exhibits a good combination of strength and toughness. Cu ions released from the Cu-added steel could effectively kill the SRB attaching on the steel surface, thus evidently decreased the pit depth and diameter of Cu-added steel. Furthermore, during the long-term immersion, the Cu-rich film formed by the enrichment of Cu in the corrosion product layer on the steel surface could also contribute to the improvement of the bio-corrosion resistance of Cu-added steel.     

X65管线钢在成品油管道沉积物中的微生物腐蚀行为

目的分析华南一成品油管道内微生物腐蚀(MIC)的主要原因及行为,为成品油管道安全运行提供支撑。方法利用微生物分析、表面分析和电化学手段,分析成品油管道沉积物中可能引发腐蚀的细菌群落,研究细菌群落协同作用下,X65管线钢的腐蚀状态,并对X65管线钢在成品油管道沉积物稀释液中的MIC行为进行分析。结果从属水平来看,成品油管道沉积物中相对丰度大于0.1%的29种菌属中有13种可能引发MIC。在实验的1～3天,天然稀释液体系(X65-Bacteria)的OCP持续正移,且正移幅度大于灭菌稀释液体系(X65-Asepsis),第3天的EIS阻抗弧半径最大。在实验的3～7天,天然稀释液(X65-Bacterias)体系的OCP负移,且负移程度明显大于灭菌稀释液(X65-Asepsis)体系。在实验的第7天,天然稀释液(X65-Bacterias)体系的阻抗弧半径小于灭菌稀释液(X65-Asepsis)体系,且自腐蚀电位更负。对生成的生物膜进行成分分析发现,生物膜和腐蚀产物膜主要由有机物和铁的氧化物组成。结论柠檬酸杆菌属(Citrobacter)和鞘氨醇单胞菌属(Sphingomonas)可能是造成华南一成品油管道沉积物中MIC的主要菌群。在管道沉积物中细菌群落的协同作用下,X65管线钢的腐蚀速度加快。     

New strain of anaerobic bacteria and its association with corrosion pitting of X52 pipeline steel

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.     

The effect of Acetobacter sp. and a sulfate-reducing bacterial consortium from ethanol fuel environments on fatigue crack propagation in pipeline and storage tank steels

This paper evaluates the effects of microbiologically influenced corrosion (MIC) on fatigue-crack growth of candidate materials useful in expanding bio-ethanol usage, including a storage-tank steel (ASTM A36) and two pipeline steels (API 5L X52 and X70). The microbiological species sampled and cultivated from an ethanol fuel production stream are responsible for both acetic acid and hydrogen sulfide production that lead to significant increases in fatigue-crack growth rate across a wide range of stress-intensity-factor amplitudes (ΔK). The mechanism for increased fatigue damage is hydrogen uptake through adsorption into the steel, which embrittles material ahead of the growing fatigue crack.     

金属表面混合微生物腐蚀及分析方法研究进展

微生物腐蚀研究一直都是金属腐蚀领域关注的热点,微生物种类的不同,对金属材料的腐蚀影响也不尽相同。实际环境中,微生物的复杂性导致单一微生物的腐蚀机理并不能完全解释实际的腐蚀现象,因此混合微生物体系研究成为微生物腐蚀领域新的研究方向。在基于单种微生物对金属的腐蚀行为及其腐蚀机理的研究基础上,综述了两种微生物的混合体系在金属表面对其腐蚀的影响。归纳总结了混合微生物的构成,重点综述了含有SRB、IOB和其他典型微生物的混合体系的作用过程,分析了混合体系中,不同微生物的相互作用(如协同、竞争作用等)对金属腐蚀影响。梳理了目前混合微生物体系研究的实验环境,并针对混合微生物体系在金属表面腐蚀微观的研究,介绍了几种技术,以期能更加直观地显示混合体系中微生物间的作用机制。最后对研究两种微生物混合体系下的金属腐蚀问题提出了建议和发展方向。     

Effect of turbulent flow on the anodic and cathodic kinetics of API X52 steel corrosion in H2S containing solutions. A rotating cylinder electrode study

This work presents the electrochemical kinetics results measured during the corrosion of API X52 pipeline steel immersed in aqueous environments, containing dissolved hydrogen sulfide (H₂S) under turbulent flow conditions. In order to control the turbulent flow conditions, a rotating cylinder electrode (RCE) was used. Five different rotation rates were studied: 0 (or static conditions), 1000, 3000, 5000 and 7000 rpm. It was found that the turbulent flow increases the corrosion rate and the corrosion mechanism for X52 steel exhibits a significant dependence on mass transfer on the cathodic kinetics.     

海洋环境下金属材料微生物腐蚀研究进展

海洋环境下的微生物易附着在金属材料表面形成生物膜,进而导致金属材料表面的微生物腐蚀(MIC)。分析了海洋环境下常见的易导致腐蚀的微生物种类及其特征,如硫酸盐还原菌(SRB)、铁氧化细菌(IOB)、产酸菌(APB)与产粘液菌(SPB)等,归纳了船舶与海洋平台涉及的微生物腐蚀及其与材料摩擦磨损的协同作用。在此基础上,重点综述了近年来碳钢、不锈钢与铜合金在海洋环境下的微生物腐蚀研究进展,包括溶解氧(DO)浓度、胞外聚合物(EPS)、生物膜微观形态等因素对碳钢MIC的影响,不锈钢在MIC过程中钝化膜与Cr元素化合物形态与含量变化,微生物抵抗Cu离子毒性机制以及铜合金在MIC过程中出现的脱合金成分腐蚀。对比了碳钢、不锈钢与铜合金表面在MIC中由生物膜、腐蚀产物与钝化膜形成的复合表面层结构差异。并从阴极去极化理论与微生物电化学腐蚀理论的角度解释了MIC,总结了两种理论间的关联性与局限性,指出了一些亟待解决的问题。     

海洋环境中油气管道的微生物腐蚀研究进展

海上油气集输管道的腐蚀能够导致严重的环境风险和经济损失，其中微生物腐蚀一直以来被认为是造成该问题的主要因素之一。针对海洋环境油气管网中腐蚀性微生物的来源进行了分类，包括油藏内源性微生物、外注海水以及微生物采油（MEOR）引入的外源性微生物。分析了海底油藏储层中流体化学物质特性，确认其富含甲烷、硫化物、挥发性脂肪酸等，并依据内源微生物代谢及产物特征进行了分类，包括硫酸盐还原菌（SRB）、产甲烷菌、发酵菌以及铁还原菌（IRB）。同时，通过举例分析某油田采出水中微生物群落丰度特征，阐明了外源微生物长期受到油田开采环境胁迫后微生物群落的变化规律。在此基础上，进一步针对海上油气集输管网内涉及的微生物代谢产物理论、电活性微生物腐蚀理论以及腐蚀性微生物之间的协同与拮抗作用进行了全面的归纳总结。最后，对目前以纯培养或模式菌株混合培养为主要方式的微生物腐蚀研究中存在的问题进行了讨论，并对基于生物技术的新型防腐手段进行了展望。     

Monitoring External Corrosion of a Pipeline Covered with a Polyolefin Tape Using Electrochemical Impedance Spectroscopy

Protection of Metals and Physical Chemistry of Surfaces - The external corrosion of a pipeline buried or submerged under specific conditions was studied. The pipelines were made of API 5L X52 steel...     

Microbiologically Induced Corrosion of X80 Pipeline Steel in a Near-Neutral pH Soil Solution

MIC of X80 pipeline steel in a near-neutral pH soil solution in the presence and absence of sulfate-reducing bacteria(SRB) was monitored by electrochemical techniques and microbiological tests. The results show that soil solution is more close to the complex soil environment around pipeline. The activity of SRB leads to the shift of the phase response to low frequency, the decrease of electrolyte resistance and the alteration of dielectric constant of the film. Both the activity and metabolite of SRB influence the corrosion behavior of the steel. The steel surface undergoes localized attack in the SRB-inoculated soil solution, whereas only slight uniform corrosion occurs in the sterile soil solution.     

Comparison of sulphide corrosivity of sulphate‐ and non‐sulphate‐reducing prokaryotes isolated from oilfield injection water

The microbiologically influenced corrosion (MIC) of water injection systems by sulphate‐reducing prokaryotes (SRP) has caused many problems in the oil industry. These prokaryotes produce H₂S, which reacts aggressively with steel and is thus widely considered to be the main cause of bacterial corrosion of industrial oil equipment. However, current microbiological treatments and controls have not taken into account other groups of sulphidogenic prokaryotes, which also produce H₂S or its derivatives and with the same adverse effects of MIC. In the present work, sulphidogenic prokaryotes were isolated from water injection systems and identified by DNA sequencing. The identified species included sulphate‐reducing Desulfovibrio termitidis and non‐sulphate‐reducing Escherichia coli. Biocorrosion tests were carried out on API 5L grade X65 carbon steel. Electrochemical impedance spectroscopy, polarisation resistance, open circuit potential and weight loss were carried out. Steel corrosion resulting from the production of the metabolite H₂S by SRP and non‐SRP was observed, with sulphide generation by SRP much greater than that by non‐SRP. These results confirm the need to investigate and consider the role of not only SRP but also non‐SRP in order to improve the control over bacterial corrosion of oil‐industry equipment.     

Development of microbially influenced corrosion on carbon steel in a simulated water injection system

Microbially influenced corrosion (MIC) on internal pipeline surfaces has become a severe problem during the water injection process in secondary oil recovery. The formation of a biofilm, normally dominated by sulfate‐reducing bacteria (SRB), is believed to be the critical step of the MIC process. A continuously fed biofilm simulating the water injection process was operated to investigate the influence of biofilm development on MIC behavior in the early phase of corrosion development. The development of the corrosion product film and biofilm was monitored for 5 months with electrochemical impedance spectroscopy, linear polarization resistance, scanning electron microscopy, 3D optical profiling, and direct weight measurement. MIC development was found to comprise three phases: initialization, transition, and stabilization. The initialization phase involved the formation of the corrosion product layer and the initial attachment of the sessile microbes on metal surface. In the transition phase, the MIC process gradually shifted from charge‐transfer‐controlled reaction to diffusion‐controlled reaction. The stabilization phase featured mature and compact biofilm on the metal surface, and the general corrosion rate (CR) decreased due to the diffusional effect, while the pitting CR was enhanced at a lower carbon source level, which supported the mechanism of direct electron uptake from the metal surface by SRB.     

温度对X52管线钢C02腐蚀电化学行为影响

利用动电位极化和电化学阻抗谱技术,研究了温度（30℃,50℃,70℃）对X52管线钢在饱和CO2的NaCl溶液中腐蚀过程的影响。由实验结果得出温度升高促进腐蚀反应的阳极过程和阴极过程,使X52管线钢腐蚀速率增大而且温度对阴极过程的促进作用大于阳极,使Ecorr正向移动;同时温度升高增大了腐蚀产物的形成速率,使其在电极表面析出并以膜层的形式存在,但温度的改变并没有改变X52管线钢在此环境下的腐蚀机理。     

Numerical simulation of a single corrosion pit in CO2 and acetic acid environments

The present paper bears on a numerical model of steady-state behaviour of a single corrosion pit in CO₂-containing media in the presence of acetic acid. The kinetics of electrochemical reactions occurring on the electrode surface is described by Tafel equations fitted to experimental data obtained on API 5L X65 pipeline steel. Simulation results provide an interesting insight into both the chemistry and electrochemistry inside the active pit. Particular attention is paid to the effect of HAc on the coupling behaviour between the attack base and the outer surrounding surface and to the comparison with experimental data obtained in similar conditions.     

Measuring and understanding the critical duration and amplitude of anodic transients

Anodic transients are known to affect buried pipeline cathodic protection (CP) systems; however, their actual effects on pipeline corrosion have not been sufficiently quantified due to the lack of direct experimental evidences. In this work, a novel methodology developed based on an electrochemically integrated multi-electrode array has been used to visualise the dynamic effects of anodic transients on localised corrosion processes occurring on buried steel surfaces. It is shown that anodic transients do not necessarily cause steel corrosion, as long as their amplitude and duration are below critical values. The electrode array is able to determine these critical values accurately due to its ability to detect localised corrosion initiation, while the conventional coupon electrode is only able to estimate these values. The critical anodic transient duration has been explained as the incubation period for the breakdown of passivity formed on the steel surface exposed to CP-generated high pH conditions.     

煤气管道用耐酸钢硫酸腐蚀行为研究

高炉煤气输送管道通常采用普碳钢,而煤气管道中含有硫酸、硝酸和氯离子等多种腐蚀性介质,对管道造成腐蚀,管道使用寿命低。针对研发的煤气管道用耐酸钢,采用均匀腐蚀全浸试验对其硫酸腐蚀行为进行了研究,利用扫描电镜(SEM)、电子探针(EPMA)、激光共焦扫描显微镜(LSCM)等手段揭示其腐蚀行为。结果表明,煤气管道用耐酸钢有优异的耐硫酸腐蚀性能;Cu、Sb、Cr等耐腐蚀元素的加入有利于改善点蚀现象,并在耐酸钢表面形成一层致密的不溶于硫酸的富含Cu、Sb、Cr等元素的钝化膜,从而增强耐酸钢的耐硫酸腐蚀性能;适量的S元素含量有利于提高钢的耐硫酸腐蚀性能。