Project Abstract

Abstract
Cathodic protection is a vital technique used to prevent corrosion in various structures and components, particularly in industries such as oil and gas, marine, and infrastructure. One common method of cathodic protection is the use of sacrificial anodes, where a more reactive metal is connected to the structure to be protected, causing it to act as a cathode and preventing corrosion of the structure. This project focuses on the design and installation of a cathodic protection system using zinc anodes. Zinc is commonly used as a sacrificial anode due to its high reactivity compared to steel and other common structural materials. The project involves the selection of appropriate zinc anodes based on the size and material of the structure to be protected, as well as the environmental conditions that may affect the corrosion rate. The design phase includes calculating the number and placement of zinc anodes to ensure uniform protection across the entire structure. Factors such as current distribution, electrical resistivity of the electrolyte, and potential gradients are taken into account to optimize the efficiency of the cathodic protection system. The installation process involves proper preparation of the structure, including cleaning and surface treatment to ensure good electrical contact between the zinc anodes and the structure. Special attention is paid to the electrical connections and monitoring equipment to ensure proper functioning of the system. Monitoring and maintenance procedures are also established to regularly check the effectiveness of the cathodic protection system. This includes measuring the corrosion rate of the structure, monitoring the electrical potential between the anodes and the structure, and inspecting the condition of the zinc anodes to determine the need for replacement. Overall, the design and installation of a cathodic protection system using zinc anodes require a comprehensive understanding of corrosion mechanisms, electrochemistry, and material properties. By implementing an effective cathodic protection system, the project aims to extend the service life of structures, reduce maintenance costs, and ensure the integrity and safety of critical infrastructure in various industries.

Project 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