The protection coverage of external galvanic cell in series and parallel connection on a buried structure

Abstract

Corrosion is an electrochemical process where surface of a material is being destroyed via its interaction with the environment. Buried structure like pipelines or undergroundtank experiences corrosion when the surface interacts with moist soil. Since these buried structures made up of metals, it to loses its electron to oxidizing species such as water and oxygen that present in soil Firstly, higher potential metal as an anode is connected to the structure to be protected which is known as sacrificial anode system. On the other hand, regardless of the type of metal used as anode, a rectifier introduced in the circuit to supply current to the metal to be protected This system is known as impressed current system. These two types of systems have respective flaws in terms of maintenance and cost. Hence, this project studies an innovative strategy by introducing an external galvanic cell that is not buried in underground. Furthermore, different types of connection also tested to study the effectiveness of this new strategy to prevent corrosion on buried structure. Apart from connection, amount galvanic cells used in the system also plays a role. Moreover, soil resistivity measurement was carried out to study the corrosivity of the soil and its effect on the cathode throughout the experiment. Since soil resistivity is very high, so the corrosion on the cathode is weak. Thus one galvanic cell is sufficient to protect the cathode from corrosion. Moreover, parallel connection is almost a good connection when two galvanic cells were used cathodic protection. Thus, suitability of connection can be determined after soil resistivity and numbers of galvanic cells are taken into consideration.