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The purpose of this paper is to develop technically efficient and economically effective sacrificial anodes that can be used for cathodic protection (CP) of pipelines in marine environment and fill the knowledge gap in the use of carbon anodes for CP.

A sacrificial anode was produced via sand casting by adding varying weight-percent of coal and ferrosilicon to a constant weight-percent of grey cast iron. The hardness of the produced anodes was evaluated using a Rockwell hardness tester. The microstructure of the anodes was observed with scanning electron microscope/energy-dispersive spectroscopy (SEM/EDS). X-ray diffraction (XRD) was used to study the phases present. A potentiostat was used to assess the corrosion behaviour of the produced anodes and mild steel in 3.5 Wt.% NaCl solution.

The SEM results showed that some anodes had interdendritic graphite formation, while others had pronounced graphite flakes. The EDS analysis showed carbon and iron to be the prominent elements in the anode. Anodes Bc, B2 and B5 with a corrosion rate of two order of magnitudes were observed to have similar dendritic structures. Anode B4 is the most electronegative with an Ecorr of −670.274 mV Ag/AgCl and a corrosion rate of 0.052475 mmpy. The produced anodes can be used to protect mild steel in the same environment owing to their lower Ecorr values compared to that of mild steel −540.907 mV Ag/AgCl.

Alloying has been majorly used to improve the efficiency of sacrificial anodes and to alleviate its setbacks. However, development of more technically efficient and economically effective sacrificial anodes via production of composite has not been exhaustively considered. Hence, this research focuses on the development of a carbon based anode by adding natural occurring coal and ferrosilicon to grey cast iron. The corrosion behaviour of the produced anode was evaluated and compared to that of mild steel in marine environment.

Reliable grounding is an important condition for the stable operation of substations and cathodic protection is one of the electrochemical protection technologies for substation grounding grids. The purpose of this paper is to consider the design proposal, installation, construction requirements and monitoring methods for Hunan 220 kV substation grounding grid.

This paper treated Hunan 220 kV substation grounding grid as a research object. The physical and chemical data of three soil samples were measured, German DIN50929 evaluation criteria were used to assess its corrosion and a sacrificial anode cathodic protection design was selected, based on advanced concepts.

The design proposal, installation, construction requirements and monitoring methods for the 220 kV substation grounding grid were clearly explained and recommended for implementation.

This paper has some guidance on design ideas and the selection method for substation sacrificial anode cathodic protection.

Probably the first use of electricity to protect ships' hulls was Edison's trailing anode technique. It was an economic failure because of the cost of the electricity and also because of misinterpretation of the rate of corrosion of the hull in moving from laboratory to full‐scale experiment. Where Davy had succeeded dramatically with sacrificial anodes Edison failed economically with impressed current. Has the situation changed today with our tremendous advances in electrical power and control techniques?

Cathodic protection is an electrical technique for preventing the rusting of iron and steel, a phenomenon which is usually considered a chemical reaction. Because of this the subject advances hand in hand with developments in electrical engineering and in the electrochemical industry and is modified in conjunction with advances in the chemical techniques for preventing corrosion. Magnesium, aluminium and zinc can be used as sacrificial anodes to provide cathodic protection and the greatest advance in this field has been the discovery of a new series of aluminium alloys which in sea‐water become cheap and effective sacrificial anodes. Impressed current techniques require a permanent anode and the plating of a very thin film of platinum on to a titanium substrate has been found to make an ideal anode. Much of the exploitation of this anode has taken place with new electrical techniques such as automatic control, the individual adjustment of anode current and a considerable improvement in the instrumentation. The extended experience of cathodic protection has given the contracting industry a very much greater knowledge of the design problems, of the spread of protection, of the degree of control and of the economic balance between the various techniques. A wider use of cathodic protection to supplement organic coatings and the development of coatings which work more readily with cathodic protection are two of the exceptional economic advances. Cathodic protection, unlike most anti‐corrosive treatments, is a continuous process, and as such it has to be maintained: the realisation of this has perhaps done more to produce the good results of which cathodic protection is capable, than any other single scientific discovery.

Once employed merely to curb pitting corrosion in condenser tubes, cathodic protection is now used throughout the circulating‐water system of a power station, and sometimes beyond.

Recent developments in marine cathodic protection have produced automatic static, solid‐state polarisation control systems. Methods are now available capable of providing complete and continuous protection of all under‐water portions of a ship's hull under any conditions. This evaluation is by a U.S. Navy engineer responsible for initiating many repairs attributable to electrolysis damage.

The parameters for Quality Control of both the anti‐corrosion coating and, where required, concrete weight coaling, are reviewed for six major pipelines in which the authors have been directly involved. The importance of field joint anti‐corrosion coatings are discussed, particularly for concrete weight coated pipelines. The differing environment of each project is identified and includes “in‐service” temperature, water depth, mode of pipe lay, together with cathodic protection considerations. The importance of quality control is traced from initial design study to coating and includes practical aspects of on‐site quality assurance. Material selection, application, inspection, safety aspects and economics are discussed.

The design engineer no longer relies on the cathodic protection engineer as half‐back to provide a cure for his corrosion problems. He must ensure their prevention from the outset. However, since he is now brought in at the design stage, the cathodic protection engineer must be capable of assessing the final prevailing conditions and requirements and assessing the economic advantages of protection. This brief historical summary, as well as stating the position of the cathodic protection engineer, outlines the inherent problems of the subject.

The purpose of this paper was to characterize the surface of steel reinforcement of concrete under cathodic protection (CP), submerged in seawater, to understand the surface changes due to the application of CP and their consequences on cathodic current requirements.

Reinforced concrete specimens with applied CP were immersed in natural seawater. The experimental methodology included monitoring of corrosion potential (E_corr); measurement of galvanic current (Igalv), protection potential (E_protection) and the depolarization potential of steel during the time of exposure; and electrochemical impedance spectroscopy (EIS). The chemical composition of the steel surface was assessed using X-ray diffraction (XRD).

The application of CP leads to the formation of a deposit on the steel surface that according to XRD results, Pourbaix diagram and physical characteristics, is a protective oxide: magnetite (Fe₃O₄). This oxide causes a decrease in the corrosion rate and requires application of the protection current. It was found that the surface remained protected even after eight days when the CP system was interrupted.

It is necessary to carry out analysis of the chemical composition of deposits formed on the steel surface, perhaps using X-ray photoelectron spectroscopy, Mössbauer, to verify the presence of the magnetite.

Determination of the main cause of the decrease in current required for protection and deposit formation conditions will enable the design of a CP system to be optimized and economized. At present, the CP design considers only a constant current value for the duration of the protection time.

CP is a technique that has proven effective for the protection of metal structures. However, little attention has been devoted to the surface changes that occur under applied CP and their impact on the electrochemical behavior of the system. This paper describes the phenomena produced at the metal surface and determines kinetic parameters and their consequences on the CP behavior.