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Principles of Cathodic Protection

Learn the basic principles of cathodic protection of engineering structures in this free online course.

Publisher: NPTEL
This free online course will give you an understanding of the basic principles of cathodic protection. The course covers the types of anodes for cathodic protection, stray current corrosion, coatings of engineering structures, and other forms of corrosion control and prevention techniques. By completing this course, you will learn a lot about cathodic protection and how to control or prevent corrosion on many engineering structures. Enrol today!
Principles of Cathodic Protection
  • Duration

    4-5 Hours
  • Students

  • Accreditation






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Cathodic protection is a method for preventing corrosion on numerous engineering structures such as pipelines, tanks, offshore structures, ships, and other engineering structures. The basic principles of cathodic protection are based on changing active areas on the surface of the structure to passive, thereby making them the cathode of an electrochemical cell. This course is aimed at giving you the details of what the principles of cathodic protection are and explaining the corrosion control and preventive measures. You will learn specific aspects of cathodic protection as applicable to storage tanks, offshore structures, and ships. The first section begins with a discussion on the various types of storage tanks, the NACE standards governing those tanks, and the simplifications involved in managing the tanks. You will also study specific issues concerning storage tanks such as the equations to estimate the potentials at the centre of cathodically protected tanks and current distributions over the tanks. Then, you will be taught the main problems and cathodic protection of the heat exchanger. The types of offshore structures, as well as marine cathodic protection, will also be discussed. Thereafter, because it is important to understand how anodes perform in order to have a better anode for cathodic protection of engineering structures, you will examine their functions and requirements. The two types of anodes for cathodic protection will be considered. You will be shown a schematic of the polarization of good and bad sacrificial anodes and how to develop an efficient sacrificial anode.

Next, you will study some equations that will enable you to better understand the concepts of cathodic protection. This will be illustrated using four worked-out examples. The worked-out examples will emphasize the role of electrochemical parameters in cathodic protection engineering, the electrochemical concepts with cathodic protection engineering, the application of electrochemical engineering concepts in the selection of rectifiers, and designing a sacrificial anode cathodic protection system. Then, you will investigate the stray current corrosion of buried structures. When considering the external corrosion of buried structures, stray current corrosion is one of the main problems that affect the structural integrity of those pipelines, storage tanks, and so on. In this section, you will discover the sources, detection, and mitigation of stray current corrosion occurring in these engineering structures. Also, AC interference is a major problem in terms of safety hazards but it can lead to corrosion issues. This segment will focus on AC interference as related to corrosion of engineering structures. The causes, factors affecting AC interference, mitigation as well as the sources of AC on pipelines will be highlighted. Thereafter, the protective coatings for the cathodic protection of engineering structures will be treated. The performance of coatings against corrosion depends on the quality of the coatings. You will come to understand why a coating is required when pipelines and other structures are cathodically protected. The requirements of protective coatings and the types applicable to pipelines will be examined in this segment. You will also be introduced to the transformer rectifier unit, the concepts involved in the selection, and the types that are applied for the cathodic protection of structures.

Furthermore, the internal corrosion of oil, gas and water pipelines will be considered. The Internal corrosion of oil and gas pipelines is not directly related to cathodic protection. Cathodic protection methodology is entirely different from the methodology to control corrosion of internal pipeline surfaces. However, it is relevant to these structures because whether it is a pipeline or storage tanks, they face corrosion externally, due to soil and internally due to the various products that they transport in the case of pipeline or store in the case of storage tanks. Study the environmental factors affecting the internal corrosion of oil, gas, and water pipelines and preventive measures.  Then you will learn about the anodic protection method which does not have much in common with cathodic protection engineering even though both use electrochemical techniques which are applied for preventing corrosion of metallic structures. You will be taught the origin, the underlining principles, how they can be applied on the field, and its limitations. The importance of anodic protection with respect to sulfuric acids will be examined. A schematic polarization curve showing the role of alloying elements and the nature of sulfuric acid on the passivity of alloys will be explained. Lastly, the comparison of anodic and cathodic protection concerning corrosion of metallic surfaces will be covered. Learning the principles of cathodic protection will help you understand and know the best control and preventive technique required for the protection and maintenance of any engineering structure. So start learning this course today.

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