Cathodic Protection

The goal of cathodic protection is to prevent corrosion by maintaining buried pipelines at a constant potential with respect to the surrounding soil. In practice, however, the implementation is very complicated since many factors can contribute to the current flowing off the pipe. Design requires characterization of the parameters impacting the corrosion process, such as soil resistivity, size of the pipe and quality of the coating.

Results of electrochemical measurements of conductive coatings, based on the mixing of pigmentary graphite in a polymer matrix are presented in this work. Electrochemical parameters are determined for the investigated coatings during long-term anodic polarisation on reinforced concrete. Based on impedance measurements the electrochemical parameters of conducting coatings are calculated. It is shown that the investigated coatings can be used in cathodic protection of reinforced concrete. The investigations show that the optimum graphite contents in coatings used for protection of concrete should be in the range from 40% to 45%.

This experimental field study interrupted the protection current offered by Impressed Current Cathodic Protection (ICCP) to ten in-service reinforced concrete structures. The study aimed to identify the long-term effects of ICCP after it was recognised that some of the systems are now reaching the end of their design life and require a significant level of maintenance. It was found that after five or more years of ICCP, the steel remained passive for at least 24 months after interrupting the protection current despite chloride contamination that would represent a corrosion risk.

Current distribution from a surface mounted anode to steel reinforcement in atmospherically exposed concrete is modelled as a function of the condition of the steel, the resistivity of the concrete and anode-steel geometry. The boundary conditions at the steel have a significant effect on current distribution with more uniform distribution arising at low steel corrosion rates. In a typical situation the surface of a steel bar facing the anode may receive 50% more current than the opposite surface. As cathodic protection has proved to be effective in these cases, a basis for many design decisions that influence current distribution is that their effect is small by comparison. When more than one layer of reinforcement is present the current distribution is significantly worse. In this case a surface anode may not be enough and discrete anodes may be necessary to improve current distribution. An increase in the concrete resistivity, cover and the anode to cathode area ratio at a constant anode current density will increase the voltage drop through the concrete inducing an improvement in the environment at the steel that promotes steel passivity. Ó

Biofilm formed on carbon steel by various species of bacterial cells causes serious problems such as corrosion of steel, choking of flow in the pipe, deterioration of the heat-transfer efficiency, and so on. Cathodic protection is known to be a reliable method for protecting carbon steel from corrosion. However, the initial attachment of bacteria to the surface and the effects of cathodic protection on bacterial viability in the biofilm have not been clarified. In this study, cathodic protection was applied to an artificial biofilm containing Pseudomonas aeruginosa (PAO1), a biofilm constituent, on carbon steel. The aims of this study were to evaluate the inhibition effect of cathodic protection on biofilm formation and to reveal the inhibition mechanisms. The viability of PAO1 in artificial biofilm of 5 mm thickness on cathodically protected steel decreased to 1% of the initial cell concentration. Analysis of pH distribution in the artificial biofilm by pH microelectrode revealed that pH in proximity to carbon steel increased to approximately 11 after cathodic protection for 5 h. Moreover, 99% of region in the artificial biofilm was under the pH conditions of over nine. A simulation of pH profile was shown to correspond to experimental values. These results indicate cells in the artificial biofilm were killed or damaged by cathodic protection due to pH increase.

Two aspects related to the deterioration process of organic coated structures under cathodic protection, detected in a previous work, are analysed: (i) why the size of failures exposing the metallic substrate can in¯uence the level of delamination and (ii) if there is a failure exposing the metallic substrate, why the appearance of blisters is fostered even away far from the original failure. The results show that an improvement of laboratory procedures for coatings selection can contribute to the development of coating/cathodic protection technology. Finally, the limitations of usual cathodic protection criteria are discussed considering the impedance measurements of samples with electrodes placed at the coating/metal interface.

The corrosion sensor should have high sensitivity enough to measure the corrosion rate in mild corrosive environments and the ability to detect the corrosion mechanism. Therefore, our goal is to develop and apply a steel thin film electrical resistance (TFER) sensor based on the measurement of changes in electrical resistance of the sensing elements in order to follow the corrosion of steel in a wide range of environments. The sensor with a thickness of 600 nm is fabricated by DC magnetron sputter deposition of steel on an Al2O3 substrate, followed by silk screen printing to improve the sensitivity of the sensor, especially to measure the corrosion rate in low corrosive environments such as anoxic corrosion in neutral solutions, steel protected by protective measures like a corrosion inhibitor or cathodic protection, and atmospheric corrosion. The sensor also has multiple-line sensing elements to detect the localized corrosion of steel. The TFER sensor is laboratory and field tested. All the studies demonstrate that the newly developed TFER sensor can be a promising and reliable tool for corrosion monitoring of steel exposed to various environments.

Incidents of failure due to corrosion/stress corrosion cracking of high-pressure gas pipelines in Pakistan have been observed to occur after about 15-20 years of service. The present paper constitutes the failure analysis of an 18-inch diameter electric resistance-welded gas pipeline. The failure was characterized, on the basis of all the available evidence and the metallurgical examination carried out on the ruptured pipe, as a stress corrosion failure that had initiated at a longitudinal 'stress raiser'. This stress raiser, which was essentially a manufacturing defect, constituted a longitudinal 'step' on the pipe surface that had resulted from the faulty trimming/shaving of the weld flash. The findings of this study, thus, emphasize the need for the care that must be taken during the shaving-off of the weld flash.

samples buried in soil have been studied in this research. Samples of unprotected carbon steel are used with other protected by different corrosion protection such as galvanic coating, rubber coating and two types of cathodic protection (impressed current and sacrificial anodes). The weight loss technique is used as a
function of the corrosion rate (mdd). The results, which have been obtained, show that the corrosion rates in the
unprotected samples are high compared with the  corrosion protected samples, and the maximum corrosion resistance is found to be at the cathodic protection
systems.

Pre-disturbance measurements of the in-situ corrosion properties of iron fittings on the snow brig James Matthews (1841) have been used as conservation management tools for the site. The wreck of the former slave trader is historically significant and the potential impact of continued industrial activities associated with nearby dredging activities necessitated in-situ cathodic protection of exposed iron fittings. A laboratory simulation study of the impact of pH and chloride content on the corrosion of cast iron and mild steel was conducted. There was a linear relationship between the corrosion rate of cast iron and the log of chloride ion concentration in the pH range 7.8< pH >5.5 with only a small pH effect noted for the given range of conditions. Studies on a 19th century mild steel sample indicated that the corrosion rate was linearly dependent on the square root of the chloride ion concentration and the corrosion rate fell in a linear fashion as the pH was increased to s...

The corrosion of metallic structures buried in soils or in contact with soils has long been a serious engineering and economic problem. All over the world many of buried structures such as (storage tanks, pipelines and critical structures foundations) are suffering from soil corrosion problems which affect mainly the external surfaces of these structures. This paper emphasizes a model defining adequate CP technique including detailed design requirements in accordance with SABIC standards & specification, international codes and standards for the external bottom of newly constructed tank bottom. ICCP Ti-MMO grid system is one of important CP technique where can be used to protect aboveground storage tank bottom. A Ti-MMO anode grid system placed between an aboveground storage tank's bottom surfaces and the secondary High Density Poly Ethylene (HDPE) liner with properly distributed power-feeders connections can protect the tank's bottom plates against external corrosion. Such systems can achieve uniform potentials along the tank bottom surfaces.

Pulse current technology (PRT) for well casing cathodic protection has been successfully applied in North America since the late 1960's. Pulse technology has been limited primarily due to a lack of understanding of how the advantages are achieved. As well, there have not been any strong case histories that clearly demonstrate pulse current success where conventional DC current could not adequately protect the casing. This paper will provide a short review of pulse technology, along with a brief review of case studies from earlier publications. This paper will also present a new case study that demonstrates the superiority of pulse current over DC current.

This article discusses the use of CP (cathodic protection) for the cost effective control of external well casing corrosion. CP is an important tool because maintaining casing integrity is essential to oil and gas production, water and gas injection, and gas storage fields. When a leak develops, production (or injection) usually ceases until the leak is repaired or a liner is installed. When corrosion is severe, the casing can collapse and the well may have to be abandoned, which can result in lost reserves. CP can be utilized in maintaining casing integrity caused by external corrosion, thereby reducing operating costs and maximizing total production and profits.

Condition assessment or controlling systems for cathodic protection of reinforced concrete structures are usually based on potential measurements. In case of permanent monitoring systems, reference electrodes are embedded in the concrete, whereas for occasional investigations external reference electrodes are normally used and placed on the concrete surface. However, ionic concentration gradients between the inner solution of the reference electrode and the concrete pore solution give rise to liquid junction potentials. In addition, internal gradients in pH or chloride content, as well as permselective properties of the cement paste lead to membrane potentials. Although these phenomena are usually not considered to be significant, they might be underestimated in many cases and lead to misinterpretation of measurement results. This is especially important with regard to applications of potentiometric sensors such as chloride or pH sensors, where accurate potential readings are fundamental. This article presents the theoretical background and summarises available literature with regard to diffusion potentials in concrete. Liquid junction potentials between various solutions have been measured experimentally. Practical consequences and possible attempts to minimise measurement errors are discussed.

Marine environment is the most severe exposure condition for reinforced concrete structures due to the presence of moisture, chlorides and sulphates. Coastal and offshore structures are subjected to time-dependent deterioration due to chemical attack and steel corrosion. The components of the concrete jetties show rapid deterioration due to the combined effects of abrasion, corrosion and changes in both temperature and moisture content. Maintenance of concrete jetties is a major concern to Port and Harbour Authorities in both developing and developed countries. This paper reviews the possible deterioration mechanisms, inspection techniques and restoration methods used for concrete jetties. Restoration methods can be grouped into four categories, namely, conventional repair, cathodic protection, chloride extraction and protective coatings. Advantages and disadvantages of these methods are discussed. Restoration strategy needs to cover issues such as (a) whether a short-term or long-term strategy is needed; (b)

The effect of zinc and tin addition to pure aluminum was investigated in 3 wt.% NaCl solution. The corrosion behavior of the elaborated samples (Al, Al–Zn and Al–Zn–Sn) was studied by open circuit potential, Tafel plot and electrochemical impedance spectroscopy. For the microstructure characterization, Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy were used. The aluminum activation increases in the following order: Al < Al–5Zn < Al–5Zn–0.1Sn < Al–5Zn–0.2Sn < Al–5Zn–0.4Sn. The impedance measurements and the microscopic observations confirmed the great activity of Al–Zn and Al–Zn–Sn compared to pure Al. The segregation at the grain boundaries leads to intergranular corrosion.

This book tries to collect the main ideas, techniques, and methods used by these prominent engineers in order to repair and rehab the large variety of structures. Furthermore, this book presents study cases of rehabilitation of structures such as bridges, buildings, garages, hotels and other exciting kind of structures. What is more, the book discuss about different types of construction as Pre-stressing, Post-tensioning, Cast-in-place, Pre-cast.

This article discusses the use of CP (cathodic protection) for the cost effective control of external well casing corrosion. CP is an important tool because maintaining casing integrity is essential to oil and gas production, water and gas injection, and gas storage fields. When a leak develops, production (or injection) usually ceases until the leak is repaired or a liner is installed. When corrosion is severe, the casing can collapse and the well may have to be abandoned, which can result in lost reserves. CP can be utilized in maintaining casing integrity caused by external corrosion, thereby reducing operating costs and maximizing total production and profits.

Teknik Elektro -D3 iii Politeknik Enjinering Indorama KATA PENGANTAR Assalamu'alaikum Wr. Wb. Puji serta syukur penulis panjatkan kepada Allah SWT yang telah melimpahkan rahmat serta hidayah-Nya, sehingga penulis dapat melaksanakan kerja praktek di PT. PERTAMINA (Persero) RU VI Balongan, dan dapat menyelesaikan laporan praktek kerja lapangan yang berjudul "PREVENTIVE MAINTENANCE USING CATHODIC PROTECTION FOR STORAGE TANK 42 T 301B and 42 T 301C PT. PERTAMINA (PERSERO) REFINERY UNIT VI BALONGAN -INDRAMAYU JAWA BARAT". Laporan ini disusun sebagai salah satu syarat memenuhi mata kuliah praktek kerja lapangan Program Studi Teknik Elektro POLITEKNIK ENJINERING INDORAMA. Laporan kerja praktek ini disusun berdasarkan data-data literature dan petunjuk serta penjelasan dari supervisor lapangan dan pembimbing. Penulis mengucapkan banyak terimakasih kepada semua pihak yang telah banyak membantu kelancaran selama kegiatan kerja praktek serta dalam penulisan laporan ini, dalam kesempatan ini penulis ingin mengucapkan terimakasih sebesar-besarnya kepada : 1. Allah SWT karena atas segala berkah dan rahmatnya penulis masih diberikan kesempatan, kemampuan dan kesabaran untuk menyelesaikan laporan kerja praktek ini. 2. Orang tua, yang telah memberikan dukungan, kasih saying dan kepercayaan serta gurauan-gurauan yang berpengaruh besar pada semangat penulis. Sehingga penulis dapat menyelesaikan laporan ini. 3. Bapak Bima O, selaku pembimbing kerja praktek di PT. PERTAMINA (Persero) Refinery Unit VI Balongan yang telah mengarahkan, memberi informasi dan selalu membimbing penulis selama kerja praktek. Laporan Praktik Kerja Lapangan Teknik Elektro -D3 iv Politeknik Enjinering Indorama 4. Bapak Yanto, Bapak Daud serta segenap staf pusdiklat yang telah membantu memberi referensi dan saran untuk penulis sehinga diberi kelancaran dalam melaksanakan kerja praktek. 5. Bapak Dr. Ir. Junaidy Burhan M.Sc. selaku kepala program studi Teknik Elektro sekaligus dosen pembimbing yang senantiasa membantu dan memberikan pengarahan kepada penulis sehingga penulis dapat menyelesaikan laporan kerja praktek ini. 6. Tiara Lidia Kani, yang selalu memberi semangat serta membantu dalam menyelesaikan laporan penulis. 7. Rekan-Rekan kuliah dan rekan-rekan Himpunan Mahasiswa Elektro PEI, yang selalu memberi dukungan moril selama kerja praktek. 8. Semua pihak yang tidak mungkin penulis sebutkan satu persatu, yang telah sangat berjasa membantu penulis selama kerja praktek di PT. PERTAMINA (Persero) Refinery Unit VI.

Corrosion Engineering–Principles and Solved Problems is based on the
author’s experience teaching undergraduate and graduate corrosion courses entitled Corrosion Engineering, Advanced Corrosion Engineering, and Electrochemical and Corrosion Techniques at the University of South Carolina. The book provides an extensive and in-depth theoretical analysis of thermodynamics kinetics, mass transfer, potential theory, and passivation, creating a foundation for understanding the electrochemical nature of the corrosion process and corrosion protection strategies discussed in the book’s second part. Around the world, the students who currently attend corrosion-engineering courses are enrolled in different engineering programs. This fact requires additional topics to be included in the book, and to this end, the book reviews the corrosion processes ,protection strategies, and testing for civil-engineering structures; corrosion in chemical process engineering; mechanical and nuclear corrosion engineering; and metallurgy. The fundamental principles of corrosion and related protection strategies are explained
through solved problems, exercises, and case studies, and the book helps upper-level undergraduate and graduate students learn the subject through an extensive theoretical description of corrosion theory, passivity, corrosion prevention strategies, and corrosion protection system design. The author has attempted to organize the book so the instructor can use it as the basis for a course in corrosion engineering for undergraduate students and also graduate students.

Build a rugged and portable device capable of performing NACE´s recommended indirect corrosion surveys. The equipment should be synchronized with a cathodic protection system through a GPS antenna. It should perform high-speed analog measurements and log the synchronized data.

This work aims to evaluate the effects of hydrogen in three high- strength steel grades. The phenomena of hydrogen (H) entry, transport and trapping inside the metals, together with the different types of damages due to the presence of hydrogen are presented. The study materials are a range of AHSS steel grades: Dual Phase Steel (DP 1000 and DP 1200) and Martensitic Steel (M 190). The hydrogen entry was performed by cathodic charging, which is suitable for industrial applications. In order to evaluate the influence of H on the steel mechanical properties, the following tests were done: H charging, to measure total H content (saturation point) and diffusible H content (embrittlement susceptibility); uniaxial tensile test of uncharged samples to determine notched tensile strength values and the strength levels at the end of elastic region and constant load tensile testing carried out in hydrogen environment, to determine the threshold values where hydrogen has an effect on the material. DP 1200 and M 190 were strongly affected by H pre-charging, as shown by the significant drop in stress required to break them. On the other hand, DP 1000 showed a lower embrittlement susceptibility, which is attributed to its lower mechanical strength. The current densities effects (0.2 up to 1.0 mA/cm²) were evaluated during H charging to measure diffusible H content. All steels showed a drop in the tensile strength i.e. experienced hydrogen embrittlement. Steels with higher tensile strength, as DP 1200 and M 190, showed a much bigger drop that is related to the favorable characteristics of martensitic microstructure regarding to the hydrogen permeability and diffusivity.

Reinforced concrete is subject to deterioration when reinforcing bars corrode as a result of chloride contamination and/or carbonation. Conventional patch repair methods are often inadequate, particularly for chloride-related problems. Cathodic protection provides a reliable long term reinstatement procedure which can be applied to most concrete structures. Reinforcing bar corrosion is becoming a significant problem in coastal areas of South Africa and the first trial installations of cathodic protection have been successfully commissioned in Richards Bay.

Pipelines and AC power transmission lines frequently share corridors leading to AC interference corrosion problems, as documented by pipeline failures that have occurred in the USA, Canada and Europe, even when cathodic protection is applied. In order to investigate these phenomena, weight loss tests on carbon steel samples were performed in soil-simulating conditions (aerated and de-aerated sulphate solutions) at various AC current densities from 10 to about 900 A/m 2 . Tests on freely corroding samples showed that the corrosion rate increased as AC current density increased; the effect of AC on corrosion rate was also detected at current densities lower than 30 A/m 2 . The results obtained are analyzed and discussed together with polarization test results, which were presented in a previous paper by Goidanich et al. (submitted for publication) [1].

I would like to thank my advisor, Dr. Alberto Sagüés, whose guidance, supervision and support from the early stages to the concluding level of this project, allowed me to finish this dissertation. Appreciation is given to my examining committee chairperson Dr. Alex Volinsky and members, Dr. R. Sen, A.

When cathodic protection is selected as a rehabilitation method for a concrete structure, there are many choices that can influence the type, effectiveness, durability and cost of the system. If the structure is complex in design and exposed to a dynamic environment, proper selection of the system components is important to suitable performance and longevity of the system. In particular, the cathodic protection system should be selected keeping in mind the owner‟s long term interests and maintenance capabilities. The purpose of this paper is to provide a general guideline to owners and design engineers for proper selection of cathodic protection systems to overcome corrosion problems on reinforced and prestressed concrete structures.

This report presents results of various tests performed to establish design guidelines for the use of impressed-current cathodic protection systems on surface-effect ships. These results show that commercially available reference cells can be used in this application, and that dielectric shield materials, which can withstand the applied voltages, are available.

This project aimed to study a comprehensive conservation plan for archaeological iron in seawater using cathodic protection as the main conservation technique. Nine cast iron cannons were discovered in 2000 just off the coast of Marettimo island (Sicily, Italy), dated between 17th and 18th century at about 15m depth, dispersed as a consequence of the sinking of a Spanish ship. The fieldwork (2017-2018) investigated two cannons, C and D, to connect them to a cathodic protection system, study degradation processes and assess how the cleaning treatment could affect corrosion processes. An innovative cathodic protection system was designed to minimize its aesthetic and physical invasiveness and, throughout the project, measurements of surface potential in different points along the external surface of the cannons had been taken. Data-loggers were used to collect time series of temperature of the water and surface potentials. One of the two cannons chosen for this research was cleaned and then its potential measurements were compared to the other one that was not. The aim of this procedure was to make the archaeological objects more recognizable and easier to study for a larger audience by partly removing marine encrustations. By cleaning the surface, exposed metal could be sandblasted and eroded; thereby a protective layer was essential. A polipropilene geotextile was used to test how effective it was as physical barrier against erosion and biological growth.

The work described here deals with the performance of ethylenediamine N,N 0 -dibenzylidene, ethylenediamine N,N 0 -di(p-methoxybenzylidene), ethylenediamine N,N 0 -disalicylidene as corrosion inhibitors for zinc in sulphuric acid. The effect of various parameters on the efficiency of these inhibitors has been studied. Ethylenediamine N,N 0 -di(p-methoxybenzylidene) and ethylenediamine N,N 0 -disalicylidene give 99% protection under a variety of conditions. Activation energies in the presence and absence of inhibitors have been calculated. It appears that an efficient inhibitor is characterized by a relatively greater decrease in free energy of adsorption, relatively lower entropy of adsorption and relatively lower heat of adsorption. Galvanostatic polarisation studies indicate that these are basically cathodic inhibitors. Cathodic protection in the presence of these inhibitors has been studied. With an efficient inhibitor, cathodic protection is achieved at potentials much less negative than that required for plain acid. The difference between protective potential and corrosion potential appears to be less for an effective inhibitor. Mechanism of the action of inhibitors has been provided.

Reinforced mortar and concrete are multi-phase composite materials at different levels of aggregation. In the framework of an extensive experimental study on cathodic protection (CP) efficiencies, the authors have investigated the electrochemical phenomena of steel reinforcement corrosion in aggressive environments by means of Electrochemical Impedance Spectroscopy (EIS). Microscopic and image analysis techniques render possible quantitative characterization of the composite microstructure at various interfaces, including structural morphology of steel corrosion and cement hydration products, pore structure, as well as the interfacial transition zones between cement paste and aggregate or bulk cementitious matrix and steel. This work aims to explore the microstructure alterations of the bulk mortar matrix and the steel/cement paste interface in reinforced mortar, relevant to corrosion and cathodic protection and compare to reference (non-corroding) conditions. Further, the morphological aspects, chemical composition and distribution of corrosion and hydration products are discussed in terms of modifying the material characteristics as consequence of the conditioning regimes. Both chloride-induced corrosion and CP are found to exert influence on the bulk material and the relevant interfaces, thus affecting the electrical properties and electrochemical characteristics, derived by EIS measurements. The correlation between EIS measurements and microstructure investigations allows breaking down the electrical properties of reinforced mortar during the corrosion process to the micro-level.

The extent of corrosion between a miniature steel ship model at different relative velocities of sea water fitted with commercial sacrificial anodes of aluminium (Al) in sea water and magnesium (Mg) in fresh water is studied. The experimental results show that the degree of cathodic protection represented by the cathode potential at a given distance from different types of sacrificial anodes decreases slightly with an increase in the relative velocity. The results also show that the amount of Al or Mg required to protect the ship cathodically increases as the relative velocity increases.

It is well known that controlled changes in the electrode potential of specimens strongly influence the behaviour of corrosion fatigue for alloys in aqueous media. In other words, the effect of polarisation on the corrosion fatigue performance of steel can be handled depending on the magnitude of applied potential. In the present work, the effect of applied polarisation potential from Ϫ750 mV (SCE) to Ϫ1500 mV (SCE) on the corrosion fatigue performance of AISI 4140 steel has been investigated by conducting a series of rotary bending, corrosion fatigue tests at 95 Hz, in aerated 3% NaCl aqueous solution. Hourglass shaped, 4 mm diameter fatigue specimens were ion nitrided at 748 K for 1 h prior to tests. It was found that corrosion fatigue life was enhanced by increasing the applied polarisation potential from Ϫ750 mV (passive range) to Ϫ1080 mV (cathodic range). Extremely rare and shallow pit formation was detected at the surface of specimens under the influence of Ϫ1080 mV potential, and the corrosion fatigue strength was increased by 2.6 times the free corrosion fatigue strength based on a fatigue life of 10 6 cycles. An improvement of 93% in fatigue strength could be attained by cathodic protection referring to the data in air for a life of 3×10 6 cycles. An attempt was made to quantify the progress in corrosion fatigue performance by using the parameter of protection ratio, PR. Over-cathodic protection at Ϫ1500 mV adversely affected the corrosion fatigue performance of ion nitrided steel due to hydrogen embrittlement, which yields an easy intergranular type of crack initiation and propagation, particularly in the case of the ion nitrided region. 

Discovering the need for more dedicated work in the conservation field relating to the preservation of historic structures with iron content and their potential for catastrophic failure through hydrogen embrittlement. Covered only in the engineering field, preservationists need to rapidly awaken to the risks that cathodic protection and seawater exposure can have on imbed rebar and learn quickly how to halt any chance of hydrogen penetration into the structural matrix

This article presents a case study of corrosion of a ship hull that began after continuous failure of the impressed current cathodic protection system. The purpose of this article is not to question or criticise the design, installation, maintenance, or operation of the cathodic protection system, but only to show through the inspection carried out that the main aspects of the corrosive process that occurred when it was anchored for more than six months. In order to leave the ship in normal operating conditions, repairs were conducted that consisted of cleaning with pressurised water blasting, welding repair of corroded plates, paint application, and installation of zinc anodes in cathodic protection replacement.

ORROSION HAS BEEN AROUND FOR ALL OF RECORDED history. Cathodic protection is the electrical solution to the corrosion problem. In this article, the history of cathodic protection (CP) is traced, and the design fundamentals are developed, including the three components of a corrosion system, the three elements of an electric circuit, and the three configurations causing potential difference. CP is the process of forcing a metal to be more negative (cathodic) than the natural state. Case studies investigate unintended side effects from CP. One is from a pipeline crossing a lake. Another is a pipeline in very rocky soil. Technical ramifications are involved when bonding of electrical grounding systems to metal protected by CP. Installation and maintenance requirements are identified. A compendium of applicable standards and recommended practices is presented. Corrosion is not exactly a new topic. It has been around since the beginning of time. Corrosion is simply the loss of material resulting from current leaving a metal, flowing through a medium, and returning to the metal at a different point, as shown in Figure [1]. Corrosion takes many forms and has various names, such as oxidation, rust, chemical, and bacteria action. Regardless of the agent, all corrosion is the result of electrical current flow. Various methods are used to treat corrosion or to try to prevent it. Some of these include chemical treatment, coatings, and electrical current [2]. Proper impressed current can stop corrosive action on the protected surface; nevertheless, this may not be practical in some environments. The concept of CP has been around for quite some time. Marine vessels have used CP for almost 200 years The first recorded use of CP occurred in the early 1800s. In 1824, © DIGITALVISION, LTD.

A novel test setup has been used in this study to simulate stress corrosion cracking initiation under a disbonded coating on an X-65 pipeline steel. In this setup, the synergistic effects of cyclic loading, cathodic protection and soil solution environment under disbonded coatings have been considered. When the X-65 pipeline steel was exposed to the test environment, there existed a wide range of corrosion products on the steel surface in the gradient of cathodic protection. Increasing the test time and the maximum stress increased the possibility of stress corrosion cracking initiation in regions with a high susceptibility to pitting corrosion.

When cathodic protection is selected as a rehabilitation method for a concrete structure, there are many choices that can influence the type, effectiveness, durability and cost of the system. If the structure is complex in design and exposed to a dynamic environment, proper selection of the system components is important to suitable performance and longevity of the system. In particular, the cathodic protection system should be selected keeping in mind the owner's long term interests and maintenance capabilities. The purpose of this paper is to provide a general guideline to owners and design engineers for proper selection of cathodic protection systems to overcome corrosion problems on reinforced and prestressed concrete structures.

Impressed Current Cathodic Protection (ICCP) has been one of the major components of the repair and maintenance strategy on many motorway structures in the U.K. It has helped to prolong the life of more than 700 structures, in a significantly sustainable manner, by reducing the need to remove chloride contaminated (but otherwise sound) concrete. This study was initiated after identifying that some of the ICCP systems were reaching the end of their design life and required a significant level of maintenance (including anode replacement) to operate in accordance with the latest Codes of Practice. In addition, there were a number of structures where the application of ICCP has been interrupted due to severe anode deterioration or vandalism.

In the present work electrochemical studies were carried out with disc electrodes of Fe–36Ni alloy in sulphate solution at pH 1?5, using linear voltammetry (LV) and electrochemical impedance spectroscopy (EIS) techniques, comparing the results with those of pure iron and pure nickel. The alloy shows a reduced corrosion when compared to pure iron, following the classical binary alloy behaviour where iron is preferentially dissolved (dealloyed) resulting in a nickel rich surface. The corrosion of Fe–36Ni alloy was further investigated under a thin electrolyte layer, where it was of interest to study the potential distribution as well as the variation of the electrochemical impedance as a function of the electrolyte film thickness. In this geometry, the corrosion current density, estimated from the low frequency (10 mHz) intercept of the EIS plot, decreases as the electrolyte thickness decreases below 500 mm, but does not change significantly while e is .500 mm.

Transmission lines are considered one of the major sources of magnetic field. In recent years electromagnetic field (EMF) interference with buried pipelines has been of great interest in the literature. The EMF interference on pipelines located in utility corridors is a real and serious problem which can place both operator safety and pipeline integrity at risk. Installing pipelines in energy utility corridors containing high-voltage AC transmission lines subjects the pipelines to induced AC voltages. This can be caused by an imbalance in the transmission system, and by high voltages near transmission tower grounding systems resulting from lightning strikes and phase faults. When a long-term induced AC voltage exists on a pipeline, it can be dangerous and potentially life-threatening for operations personnel to touch the pipeline or appurtenances. In addition, pipe corrosion also can result from AC discharge. Due to the wide lands of Saudi Arabia and its long water and oil pipelines...

Impressed current cathodic protection (ICCP) is a widely used method to protect steel reinforcements against corrosion. Bond degradation between concrete and steel at protection and overprotection levels was studied. Two types of materials were tested: an ordinary Portland cement (OPC) and a mixture of 85% OPC and 15% fly ash (OPC/FA). Concrete specimens were immersed in a 3.5% sodium chloride (NaCl) solution. Chemical analysis of sodium, potassium and hydrogen ions was performed using atomic absorption spectrophotometry (AAS). Hydrogen ion content was monitored using electrochemical impedance spectroscopy (EIS). Mechanical behaviour was analysed by means of pullout tests, and microstructure characterisation was carried out using scanning electron microscopy (SEM). Sodium, potassium and hydrogen ions were found at the concrete-steel interface. The mechanical properties of the specimens were poorer at overprotection level than at protection level.

Cathodic protection (CP) is considered to be the only rehabilitation method for chloride-induced rebar corrosion in reinforced concrete structures. The protection current distribution depends on several parameters, such as the geometry and number of rebars and the concrete resistivity. In order to investigate the influence of concrete resistivity on the possibilities and limitations of rebar protection, this paper presents a numerical approach based on the finite element method (FEM) in conjunction with laboratory results to determine its impact on the CP of alkali-activated slag mortar. An ordinary Portland cement was also tested for comparative purposes.