Thesis Abstract

Abstract
Cathodic protection is a widely used method for preventing corrosion in various structures and components. This research project focuses on the design and installation of a cathodic protection system utilizing zinc anodes. Zinc is commonly used as a sacrificial anode material due to its high electrochemical potential compared to other metals. The primary goal of this study is to investigate the effectiveness of zinc anodes in protecting a steel structure from corrosion. The design process involves determining the appropriate number and placement of zinc anodes to ensure uniform protection across the structure. Factors such as the size of the structure, the corrosive environment, and the expected lifespan of the system are considered in the design phase. Computer simulations and modeling techniques are employed to optimize the design parameters and predict the performance of the cathodic protection system. The installation phase of the project involves preparing the surface of the structure, attaching the zinc anodes, and connecting them to a power source. Proper installation techniques are crucial to ensure the efficient operation of the cathodic protection system. Monitoring and maintenance protocols are also established to regularly assess the performance of the system and make any necessary adjustments. Experimental testing is conducted to evaluate the corrosion protection provided by the zinc anodes. Electrochemical measurements are taken to monitor the corrosion rate of the steel structure with and without the cathodic protection system in place. The results of the testing provide valuable data on the effectiveness of the zinc anodes in preventing corrosion and extending the lifespan of the structure. Overall, the research project aims to demonstrate the practical application of zinc anodes in cathodic protection systems. By investigating the design, installation, and performance of such a system, this study contributes to the body of knowledge on corrosion prevention techniques. The findings of this research can be valuable for engineers, designers, and maintenance professionals involved in the protection of steel structures from corrosion.

Thesis Overview

INTRODUCTION

1.1 Background of study

Cathodic protection (CP) is a method of controlling corrosion or a means of preventing corrosion of metal and can be applied to any buried and/or submerged metallic structures. It is normally used in conjunction with coatings and can be considered as a secondary corrosion control technique.

Cathodic protection can, in principle, be applied to any metallic structure in contact salty media (electrolyte). In practice its main use is to protect steel structures buried in soil or immersed in water. Structures commonly protected, includes:

    Cross country pipelines

    Exterior surfaces of pipelines immersed in water

    In plant piping

    Above ground storage tank bases

    Buried tanks and vessels

    Internal surfaces of tanks, vessels, condensers and pipes

    Well casings

    Foundation piling, steel sheet-piling

    Piling – tubular, sheet steel and foundation

    Marine structures including jetties, wharfs, harbours, piers

    Ships, hulls

    offshore platforms

    Reinforcing steel in concrete

Corrosion is a very serious problem. Three areas in which corrosion are important are in economic, improved safety and conservation of resources. The leakage of hazardous materials from a transport pipeline represents not only the loss of natural resources but also the potential for serious and dangerous environmental impact, and human fatalities. While pipelines are designed and constructed to maintain their integrity, diverse factors (e.g., corrosion) make it difficult to avoid the occurrence of leakage in a pipeline system during its lifetime.

All metals needs energy to be transformed from their oxide (natural) state to a refined state. The process of taking this energy away from the metal is called corrosion. Metals tend to revert back to their natural state when reacting with the environment. This corrosion reaction that occurs is an oxidation-reduction reaction. The purpose of cathodic protection is to stop this corrosive process.

Cathodic protection is the most important of all approaches to corrosion control techniques. One of the types of cathodic protection is sacrificial anode or galvanic cathodic protection. Corrosion occurs through the loss of the metal ions at anodic area to the electrolyte. Cathodic areas are protected from corrosion because of the deposition of hydrogen or other ions that carry current (Sandoval, A., et.al 2001). By using the sacrificial anode technique, the steel pipe will be protected from corrosion but the other metal which is the anode will corrode. In designing this method we must analyze parameters such as factor affecting corrosion, the amount of anode and rate of corrosion, the current densities and the total resistance.

Corrosion is an electrochemical process in which a current leaves a structure at the anode site, passes through an electrolyte, and reenters the structure at the cathode site. Differences in potential at different points along the pipe begin to develop. For example, because it is in a soil with low resistivity compared to the rest of the line, current would leave the pipeline at that anode site, pass through the soil, and reenter the pipeline at a cathode site. These potentials generate corrosion currents which leave the pipe to enter the soil at certain selective locations.