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Collaborating Authors
Water Management
ABSTRACT Power plants have experienced severe corrosion, including microbiologically influenced corrosion (MC) in cooling water systems. This attack has resulted in decreased plant availability and significantly increased operations and maintenance costs. Copper base alloys, carbon steels and stainless steels have all been susceptible. In a number of instances, replacement of piping and beat exchangers has been required to alleviate corrosion-related problems. Monitoring is a key element to improved corrosion and fouling control in cooling water systems. On-line methods provide evaluations of corrosion rates in real time and are sensitive to localized corrosion. Electrochemical methods of corrosion measurement are readily automated, both for acquisition of corrosion data and for process control. Electrochemical probes for on-line monitoring of biofilm activity were exposed to a slowly flowing, brackish cooling water environment to assess system performance at Pacific Gas & Electric Company’s Pittsburg Power Plant. BACKGROUND Many industries, including nuclear and fossil-fueled power plants, oil and gas production, chemical processing, pulp and paper, transportation, and water distribution networks have experienced damage due to corrosion in natural waters. This damage results in increased downtime of equipment, increased operating costs, and can jeopardize the safe operation of plant equipment. These industries have recognized the importance of corrosion control on continued reliability and economic operation of their plants. In most circumstances, general corrosion has been adequately controlled or addressed during design. Localized corrosion due to pitting crevice corrosion, underdeposit corrosion, or microbiologically influenced corrosion (MIC) has, of necessity, received greater attention during the 1980s and 1990s. Methods for control of localized attack require a greater understanding of the types of local environments that can exist in power plant equipment. The power generation industry has devoted increasing attention to corrosion monitoring and monitoring of biofilm activity in cooling water environments, These environments range from “soft”, fairly low conductivity fresh waters to scale-forming freshwater to brackish waters and seawater. Monitoring tools for a power plant must address the corrosion concerns associated with that plant’s cooling water, including both the seasonal fluctuations that may be expected and the creation of local environments due to corrosion products, deposits, and microbiological growth. Simple to use. Installation and routine maintenance of the monitor(s) should not impact power plant operations. Simple to interpret. Results should be readily interpreted by operations personnel. Corrosion specialists should not need to be consulted routinely. Outputs should be amenable to automation (alarms, etc.). Rugged. The probes and equipment must be sufficiently rugged that frequent, unscheduled maintenance is avoided. Sensitivity to external noise (e.g., welding, the plant’s turbine-generators) is unacceptable. Sensitive. Detectable electrochemical effects should appear on the probe before thick biofilms are established on plant components. Accurate. A monitoring device must provide reliable detection of biofilm activity with a minimum of false calls. Economical. Cost for installation, maintenance, and operation must be cost effective, as reflected by potential savings realized as a result of the improved monitoring capabilities. On-line monitors must be:
- North America > United States > California (0.68)
- North America > United States > Texas (0.47)
- Energy > Power Industry (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Lifecycle > Sourcing (0.61)
ABSTRACT API or proprietary test-kits presently used for the detection of bacteria involved in microbial corrosion are designed for specific detection of sulfate-reducing bacteria (SRB). It was recently shown that other sulfidogenic bacteria such as thiosulfate-reducing bacteria (TRB) are also involved in the corrosion of carbon steel. Since these bacteria cannot be detected by SRB test-kits, a new kit was developed for TRB detection. INTRODUCTION The bacteriological monitoring of microbial corrosion currently focus on the specific detection of SRB. API detection kits are widely used, as well as improved proprietary test-kits which recently allowed the detection of numerous new SRB species In 1989, Elf Congo experienced corrosion of a 22 km main subsea line that transported sour oil. An extensive campaign of sampling and microbiological study was undertaken that unexpectedly revealed the presence of several non SRB, strictly anaerobic, thiosulfate-reducing bacteria. These microorganisms were detected all over the oil field facilities, from wellheads to pipelines. Although thiosulfate-reduction is a common metabolism in the bacterial world, its implication regarding microbially influenced corrosion had never been investigated before. Subsequent work showed that TRB are widely distributed within oil and gas production facilities, as well as in brines of other industries. This metabolic bacterial group is actually composed of a wide variety of different micro-organisms, including halophilic, mesophilic or thermophilic species*. Some of them belong to already known genera or species, but new species and new genara were also discovered. These bacteria share several metabolic traits, such as the use of amino-acids or peptides as the main nutrients, the production of organic acids as the terminal end-products of their carbon metabolism, and the reduction of sometimes unusually high amounts of hydrogen sulfide due to thiosulfate-reduction This type of metabolism is partly similar to SRB metabolism, except that hydrogen sulfide production is due to thiosulfate-instead of sulfate-reduction. Since acid and H2S production is considered as a major feature in microbial corrosion, and since TRB can produce much higher amounts of H2S than SRB, TRB can be considered even more dangerous than SRB for facilities where thiosulfate can be available. This hypothesis recently received its first confirmation by electrochemical measurements of localized corrosion by a TRB strain. DESIGN AND LABORATORY EVALUATION OF A TRB TEST-KIT The TRB test-kit is very similar in its presentation to the API SRB test-kit. It is composed of 10mL penicillin-type flasks, containing 9mL of the liquid detection medium in an oxygen-free atmosphere. Syringes are used to inoculate the sample through the rubber stopper. As for SRB detection, TRB development is visualized by the appearance of a black FeSx precipitate following bacterial growth. The culture medium, the composition of which is proprietary and cannot be detailed here, was designed according to the known metabolic properties shared by TRB, and supplemented with some nutrients allowing the detection of slow-growing micro-organisms. The salinity of the medium can be adjusted according to the characteristics of the sample, and TRB test-kits have to be incubated at a temperature corresponding to the in-situ conditions.
- Europe (0.48)
- North America > United States > Texas > Harris County > Houston (0.15)
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Constituents > Bacteria (0.72)
The Role Of Metal-Reducing Bacteria In Microbiologically Influenced Corrosion
Little, Brenda (Naval Research Laboratory) | Wagner, Patricia (Naval Research Laboratory) | Hart, Kevin (Naval Research Laboratory) | Ray, Richard (Naval Research Laboratory) | Lavoie, Dennis (Naval Research Laboratory) | Nealson, Kenneth (Center for Great Lakes Studies University of Wisconsin) | Aguilar, Carmen (Center for Great Lakes Studies University of Wisconsin)
ABSTRACT Synthetic iron oxides (goethite, aFeO.OH; hematite, Fe2O3; and ferrihydrite, Fe(OH)3) were used as model compounds to simulate the mineralogy of passivating films on carbon steel. Dissolution of these oxides exposed to pure cultures of the metal-reducing bacterium, Shewanella putrefaciens, was followed by direct atomic absorption spectroscopy measurement of ferrous iron coupled with microscopic analyses using confocal laser scanning and environmental scanning electron microcopies. During an 8-day exposure the organism colonized mineral surfaces and reduced solid ferric oxides to soluble ferrous ions. Elemental composition, as monitored by energy dispersive x-ray spectroscopy, indicated mineral replacement reactions with both ferrihydrite and goethite as iron reduction occurred. When carbon steel electrodes were exposed to S. putrefaciens, microbiologically influenced corrosion was demonstrated electrochemically and microscopically. INTRODUCTION It has been established that the most devastating microbiologically influenced corrosion (MIC) takes place in the presence of microbial consortia in which many physiological types of bacteria interact in complex ways. However, many of the organisms in these consortia have yet to be characterized and the nature of the complex interactions remain uncharacterized. The groups of organisms that are most often cited as causative are the sulfate-reducing bacteria (SRB) and metal-depositing bacteria. SRB produce sulfide, initiating a variety of corrosive reactions, while metal-depositing bacteria produce visible tubercles (manganese and/or iron oxides) that are unmistakable in their appearance. SRB are ubiquitous and easily cultured and quantified. Several diagnostic kits have been developed for SRB based on sulfide reactions with metals, or the presence of specific enzymes, such as hydrogenases or reductases. A group of organisms about which much less is known in terms of role(s) in corrosion are the dissimilatory metal reducers. Dissimilatory iron and/or manganese reduction occurs in several microorganisms, including anaerobic and facultative aerobic bacteria. Inhibitor and competition experiments suggest that Mn(IV) and Fe(III) are efficient electron acceptors similar to nitrate in redox ability and are capable of out-competing electron acceptors of lower potential, such as sulfate or carbon dioxide. Many of the recently described metal reducers are capable of using a variety of electron acceptors, including nitrate and oxygen.Assimilatory ferric reductases are common to almost all aerobic bacteria, which must obtain iron under conditions where it is at low concentrations due to its spontaneous oxidation to insoluble ferric oxides. Such bacteria use high affinity iron-binding compounds called siderophores to scavenge the rare iron from the environment. Siderophore- Fe(III) complexes are then transported into the bacterial cells where the iron is reduced enzymatically and released from the siderophore. Enzymes with iron reductase activities have been detected in soluble fractions of Escherichia, Pseudomonas, and Bacillus, among others.In the early 1980s Westlake and colleagues reported isolation and characterization of a bacterium capable of dissimilatory iron reduction. This organism, originally identified as Pseudomonas ferrireductans and subsequently reclassified as Shewanella putrefaciens, was isolated from mine tailings and oilfield samples. S. putrefaciens can use an array of electron acceptors including o
- Materials > Metals & Mining (1.00)
- Materials > Chemicals (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Constituents > Bacteria (0.74)
ABSTRACT Current metal primers utilized by the US Air Force contain chromates to inhibit corrosion of the underlying metal. These chromates are both highly toxic and carcinogenic and pose a severe health risk to personnel involved in their application, stripping and disposal. Environmentally-friendly primers with chromate replacements have historically performed poorly with respect to corrosion inhibition. The purpose of this study was to investigate the interaction of chromates with microorganisms in an environment not traditionally associated with biologically-enhanced corrosion to determine if corrosion inhibition by a chromate pigment is, in part, through its action as a biocide. Inoculation of panels which had been coated with a nonchromated primer prior to salt fog exposure and storage in humid conditions resulted in a significant growth of filiform corrosion around a scribe mark. The presence of chromate in the primer severely limited the formation of this corrosion. Likewise, in the absence of the inoculation procedure, the extent of corrosion was strongly diminished. These results suggest that the chromate may be acting as a biocide to limit corrosion which is enhanced by the presence of biological activity. INTRODUCTION Primary and secondary structures on aircraft are susceptible to corrosion under normal service conditions. Many of these metallic and polymer composite structures can be adequately protected against corrosion by organic coatings. However, routine maintenance and special mission requirements often require periodic stripping of these coatings during the ever-increasing life cycle of the aircraft. The application and disposal of these coatings can cause substantial environmental pollution problems. Current metal primers utilized by the US Air Force contain chromates to inhibit corrosion of the Underlying metal. These chromates are both highly toxic and carcinogenic and pose a severe health risk to personnel involved in their application, stripping and disposal. The health risks are of particular concern during the stripping and disposal processes utilized prior to refinishing the metal surfaces. Environmentally-friendly primers with chromate replacements have historically performed poorly with respect to corrosion inhibition. Microorganisms have been shown to both initiate and accelerate corrosion in many environments. The premise of this study was to investigate the interaction of chromates with microorganisms in an environment not traditionally associated with biologically - enhanced corrosion, to determine if corrosion inhibition by a chromate pigment is, in part, through its action as a biocide. The results of this investigation will provide some guidance in the search for environmentally - friendly chromate replacements. EXPERIMENTAL PROCEDURE Primers with and without chromium are required to investigate the premise that chromates act as a biocide to limit biologically-enhanced corrosion of a coated metal substrate. Two polyamide-based primers were obtained from DEFT, Inc. The primer compositions were essentially identical with the exception that one primer contained barium chromate as a corrosion inhibitor, while the other did not contain any corrosion inhibitor. The primers were prepared as directed by the manufacturer. Clad 7075 aluminum was the substrate used in this study, sectioned into panels measuring approximately 7.6 mm by 15.2 mm.
- Water & Waste Management > Water Management (1.00)
- Government > Military > Air Force (0.96)
- Materials > Chemicals (0.88)
ABSTRACT The souring of normally sweet production systems is a significant problem which can have implications to continued oilfield operations. Such problems are commonly approached by gathering of field sample and laboratory analysis or by simple test kits, This paper describes an alternative approach which includes the use of specialized field sampling and analysis procedures and portable equipment that can be move from site to site. A case study is presented that illustrates the use of these procedures and equipment. In the present case, it was learned that whereas souring was occurring in oil producing wells, no major infection of SRB was found. Evaluation of the injection wells indicated only limited inflection. Based on field studies it was found that the problem was likely due to maintenance of a sessile SRB population in the injection system due to a combination of GHB and accumulation of solids followed by growth of mesophilic SRB in the formation after injection. Remedial actions were developed based on field data and this mechanism of reservoir souring. INTRODUCTION The souring of normally sweet production systems is a significant problem. It can have implications in terms of ( 1) reduced quality of produced hydrocarbons relative, (2) the reduced productivity of wells, (3) increased corrosivity of produced fluids. In cases where remedial action is not taken, it can also have implications relative to the potential for sulfide stress cracking and selection of materials for downhole, flowlines and surface facilities. Therefore, it is important to be able to properly characterize field situations and make accurate recommendation for remedial actions to minimize the impact of souring and to prevent the occurrence of similar occurrences in other related field operations. Is the souring a direct consequence of bacterial action. Whether the bacteria were introduced by the water injection system. Are the bacteria naturally occurring in the reservoir. Can the bacteria survive and grow under reservoir conditions. How adaptable are they to varying field conditions. Are there sufficient nutrients to sustain bacterial growth in the system What is the potential for control. In an assessment of reservoir souring, field analysis provides an important technical basis for engineering decision making through their supporting scientific evidence. Such tests can yield information useful in determining the sources and the potential severity of souring and the selection and confirmation of successful remedial actions. Some of the significant questions that can be addressed through field investigation are indicated below:Field souring is often studied by either of two approaches: (1) field sampling followed by transportation of the samples to the laboratory for analysis, or (2) analysis directly in the field using simplified field test kits. In many cases, the field sampling/laboratory approach is difficult due to the remote nature of many onshore and offshore production and injection facilities and the inability to transport, maintain and analyze cultures. Additionally, most simple field tests lack the sensitivity required to properly assess, characterize and differentiate marginal cases.
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (0.57)
- North America > United States > Texas > Permian Basin > Delaware Basin > Thistle Field (0.99)
- Asia > Middle East > Oman > Ad Dhahirah Governorate > Arabian Basin > Rub' al-Khali Basin > Block 6 > Lekhwair Field > Thamama Group > Thamama Group > Shuaiba Formation (0.99)
- Asia > Middle East > Oman > Ad Dhahirah Governorate > Arabian Basin > Rub' al-Khali Basin > Block 6 > Lekhwair Field > Thamama Group > Kharaib Formation > Shuaiba Formation (0.99)
ABSTRACT Aluminum-clad spent nuclear fuels are being stored in water in the Receiving Basin for Off-site Fuels (RBOF) and the reactor disassembly (cooling) basins at the Savannah River Site (SRS). Experience shows that fuels stored in water are subject to rapid pitting corrosion if the water quality is poor. Upgrade projects and actions, including those to improve water quality, were recently undertaken to upgrade the disassembly basins for extended storage.A technical strategy was developed for continued basin storage of aluminum-clad fire] assemblies. The strategy includes development and implementation of basin technical standards for water quality to minimize attack due to pitting corrosion over a desired storage period. In the absence of localized corrosion, only slow, general corrosion of the cladding would be expected.A laboratory corrosion program is being performed to provide the bases for technical standards by identifying the region of “aggressive” water qualities where existing oxide films would tend to break down and pits would initiate and remain active. Initial results horn corrosion potential and cyclic polarization testing of aluminum alloys in various water chemistries have shown that low conductivity water (<50 µS/cm) should not be aggressive to cause self-pitting corrosion. Initial results from tests of 8001 and 5052 aluminum and aluminum- 10%urarrium alloy indicate that a strong galvanic couple should not exist between the aluminum cladding materials and the ahrminum-urau.hun fuel. Additional laboratory testing will include immersion testing to allow characterization of the growth rate of active pits to benchmark a kinetic model. This model will form the basis for a water quality technical standard and enable prediction of the life of aluminum-clad spent nuclear fuels in basin storage.INTRODUCTION AND BACKGROUND INFORMATIONThe United States Department of Energy (DOE) has selected the Savannah River Site (SRS) as the location to consolidate and store aluminum-clad spent nuclear fuel from foreign and domestic research reactors. Fuel storage basins at the SRS will be receiving aluminum-clad fuels from domestic and foreign research reactors (DRR and FRR, respectively). Extended basin (wet) storage of spent nuclear fuels from the SRS reactors and from the DRR and FRR may be implemented as a de facto alternative for interim storage while technologies are developed and decisions are made for interim storage and ultimate disposal.Successful extended storage of spent nuclear fuels in water basins would involve avoiding unacceptable degradation of the fuel throughout the desired storage period. Degradation of the fuel involves mechanisms that can cause a loss in net section of the cladding, distortion of the fuel, or a loss of fuel and fission products into the water.Aluminum-clad fuel assemblies that have been stored in basins may have been subjected to pitting corrosion conditions. Storage histories have shown that pitting can occur via local breakdown in the protective, passive film under poor water quality conditions. A project to support continued interim storage of fuel assemblies in the reactor disassembly basins, the Disassembly Basin Upgrade Project, is nearly complete.
- Water & Waste Management > Water Management (1.00)
- Government > Regional Government > North America Government > United States Government (1.00)
- Energy > Power Industry > Utilities > Nuclear (1.00)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Health, Safety, Environment & Sustainability (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
Effects Of Eta, Ph Change, And Increased Hydrazine Levels On Deposit-Covered Alloy 600 And Brass Corrosion
Barkatt, Aaron (The Catholic University) | Labuda, Ewa (The Catholic University) | Wilder, Donna M. (The Catholic University) | Smialowska, Susan (The Ohio State University) | Rebak, Raul B. (The Ohio State University) | Cherepakhov, Gahna (Consolidated Edison Co. of New York, Inc) | Bums, Reynolds J. (Consolidated Edison Co. of New York, Inc)
ABSTRACT Chemical dissolution tests and electrochemical tests were carried out on Alloy 600 specimens covered with synthetic deposit simulating the tube deposits in the steam generators at Indian Point 2. The tests showed that the introduction of ETA and a moderate increase in pH gave rise to lower corrosion rates, but enhancement of hydrazine levels caused them to rise. In the case of brass, both types of tests showed that raising the pH caused the corrosion rates to increase, but the introduction of ETA led to mild decrease in these rates. INTRODUCTION in recent years many nuclear plants implemented changes in secondary water chemistry in an effort to minimize corrosion in the secondary system and to reduce the extent of transport of iron into steam generators. Until the late 80’s, most plants used ammonia to control the pH of secondary water. Most recently, advanced amines, such as morpholine and ethanolamine (ETA) were introduced. These amines are less volatile than ammonia, and therefore they are more effective in maintaining a high pH at steam generator temperatures. However, it was recognized that the implementation of advanced amine chemistry requires evaluation of its consequences on a site-specific basis, taking into account the materials of construction and the past and present operating conditions in individual plants. The Indian Point 2 Station is a 995-MWe PWR with four Model 44 Westinghouse steam generators. It started operations in 1973. Many of the original components of the secondary system were made out of copper alloys (admiralty brass, cupronickel). Although many of these components were later replaced by stainless steel or titanium components, the low-pressure heaters and one condenser still consist of copper-based materials. In addition, much copper (some of it in oxide form) is still present in deposits and sludge accumulated in the steam generators. accumulation of relatively large amounts of sludge and deposits in the steam generators. Some of the accumulated material is quite hard. The build-up of sludge has required lancing during each refueling outage since the beginning of operations. However, tube corrosion has been limited to mild pitting. No secondary-side SCC has been observed. Through the 1995 outage, only about 9% of the total number of tubes have been plugged. More significantly, less than 6% of the tubes have required plugging since the start of full-power operation. The specific features of the secondary system (presence of copper, sludge build-up, mild corrosion) had to be taken into account during the evaluation of the introduction of ETA into the secondary system at Indian Point 2. In particular, it was necessary to find out whether ETA might cause enhanced dissolution of the brass components or of the accumulated deposits and hard sludge. Dissolution of the latter materials is undesirable, because microstructural examination by SEM/EDX and radiotracer migration studies showed that the deposits and hard sludge form barriers to the migration of corrosive species such as sulfate, chloride, and lead.
- Energy > Power Industry (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.95)
- Water & Waste Management > Water Management > Water & Sanitation Products (0.93)
- (2 more...)
ABSTRACT The use of volatile corrosion inhibitor (VCI) paper materials for protection of ferrous parts has been standard practice for years. Periodically, failures have occurred on various component parts with no apparent explanation. A failures analysis was performed on 20mm ammunition and residual chlorine was found to be present. This paper identifies the potential source of the halogen contamination. BACKGROUND Over the past 10 years, corrosion problems have been experienced with the use of volatile corrosion inhibitors (VCIs). The specific form in all these cases was VCI paper products. The causes of failure have been summarized as follows: Inadequate closures - allowing the volatile protestant to escape. Severe corrosion environment-an environment exceeding the VCI’s protection capability. Improper storage prior to use - VCI allowed to escape prior to closure Material incompatibility - packaging materials releasing acidic corrosive vapors. Non-Qualified Product List (QPL) material - use of products not tested per the specification. Excessive oil absorbed by the paper - paper unable to properly release VCI. Every one of these situations is a story in itself and, as it can be seen, results in some type of material/process variable that can exist. All the testing on VCIs properly applied shows that bare steel can be adequately protected for up to 30 years. None of the application problems cited above involved the use of bare steel. These failures were observed on zinc phosphate coated parts with or without a supplemental oil. See Figures 1-4. While all the above situations may result in the demise of a protection system utilizing VCIS, rarely ever could the cause of these failures be documented with a failure analysis. The failures would occur anywhere within a few months to a few years after the manufacturing and packaging were completed. There was no way to go back and actually validate the suspected cause. The contractor would blame the government QPL material. The government would blame the contractor for improper handling packaging, or phosphating. In another case, an independent analysis blamed incompatibility with another packaging material, i.e., a problem with the packaging instructions in the technical data. The bottom line was always that someone had to begrudgingly pay to fix the problem. A few years ago, corrosion was occurring on 20mm projectiles that were zinc phosphate coated steel. The projectiles that failed were packaged with a VCI material. An analysis was conducted in an attempt to establish the cause of the problem. A scanning electron microscope (SEM) with an X-ray analyzer was used to examine the surface and determine what elements were present. When chloride was found in the corroded area along with oxygen and iron (See Figure 5), the source of the chloride was a complete mystery. About the same time, corrosion was occurring on zinc plated parts that were given a supplemental zinc phosphate coating. The X-ray analysis on the SEM showed chlorine and bromine. See Figure 6. These situations began a three year effort to unveil the mystery.
- Water & Waste Management > Water Management > Water & Sanitation Products (0.88)
- Materials > Chemicals > Specialty Chemicals (0.88)
Abstract Because of government mandated industrial pretreatment, longer detention times for waste water due to construction of regional treatment plants, recent air quality regulations, and other factors, concrete structures in waste water treatment plants are exposed to more severe exposure conditions now than in the past. Protective coating systems which had performed successfully for many years no longer provide adequate protection. The result is frequent coating failure and rapid concrete degradation. This paper discusses the more aggressive service conditions today and the changes which have promoted them. The paper will give examples and then present suggested material selection criteria to be used in the future by engineers and operators to ensure successful long term corrosion protection of concrete structures in municipal Waste Water Treatment Systems.
INTRODUCTION AND BACKGROUND Hydrogen sulfide
- Water & Waste Management > Water Management > Water Supplies & Services (1.00)
- Water & Waste Management > Water Management > Lifecycle > Treatment (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Health, Safety, Environment & Sustainability > Health > Noise, chemicals, and other workplace hazards (1.00)
- Health, Safety, Environment & Sustainability > Environment (1.00)
Abstract The corrosion behavior of fusion-bonded epoxy coated steel reinforcements (FBECR), with and without artificial damage, embedded in concrete and immersed in sodium chloride solution has been determined. Four degrees of damage namely 1%, 2%, 3% and 4% were utilized. The corrosion of some of the samples was accelerated by shifting the corrosion potential of the reinforcing steel into the anodic region. Using electrochemical corrosion measurement techniques, the corrosion behavior of FBECRS embedded in concrete was determined. Results obtained from the study indicate that the area of pre-existing damage in the coating of the steel bars correlates well with the corrosion behavior of samples subjected to accelerated corrosion. Samples with 40/odarnage showed the highest susceptibility to accelerated corrosion followed by 3%, 2% and 1% damage samples. Also, the coating that was applied manually to the ends of the steel bars showed very poor performance. Samples with and without damage tested at the free corrosion potential were not affected by corrosion over the short testing period of the experiment. INTRODUCTION The deterioration of concrete structures due to reinforcement corrosion is a major concern to the construction industry in the coastal areas of the Arabian Gulf. Field studies conducted at King Fahd University of Petroleum and Minerals indicated that the concrete structures in this region deteriorate within a short fraction (less than 10 years) of their design life [1-3]. The aggressive environment conditions, characterized by high temperature and humidity variations, atmosphere contaminated with chloride and sulfate, and weak and absorptive aggregates are the primary contributors to the deterioration of concrete structures. Epoxy-coated reinforcement is an innovative procedure developed in tie 1970sto tackle the bridge deck deterioration due to corrosion of the reinforcing steel. The first major application of epoxy-coated reinforcing bars was installed in 1973 in a Pennsylvania bridge deck. But FBECR did not become commercially available in the market until 1976. Since then, its usage has been continually increasing. FBECR has been specified for new and replacement bridge decks by over 40 of the 50 state highway departments in the U.S.A.; the bars are also used in other parts of bridge structures, e.g., piers and parapets. In recent years, usage has spread to many other types of reinforced concrete structures such as parking garages, marine structures, waste water treatment plants, cooling towers, and other parts of power plants and subways [4]. The experience at the Florida Keys Bridges [5] in later years provided valuable information on the applicability and limitations of epoxy-coated rebars in similar service. Severe corrosion of epoxy-coated reinforcing steel was documented at major construction projects in a subtropical marine environment. The corrosion was caused by the combined effect of several factors. These included two primary factors: (1) mechanical coating damage and weathering exposure prior to concrete casting, and (2) macrocell action during service in a severe corrosive environment. An unexpected failure mechanism involving progressive loss of adhesion and underfilm corrosion were identified in field structures with “perfectly” coated rebars in the salt-contaminated environment [6].
- North America > United States > Texas (0.28)
- North America > United States > Florida (0.28)
- North America > United States > Pennsylvania (0.24)
- Research Report > New Finding (0.68)
- Research Report > Experimental Study (0.68)
- Materials > Construction Materials (1.00)
- Construction & Engineering (1.00)
- Water & Waste Management > Water Management > Lifecycle > Treatment (0.88)
- (2 more...)