Comparative Analysis of Cathodic Protection of Steel Pipeline under the Sea using Different Sacrificial Anodes

Abstract

Corrosion is a major problem in piping system systems specially in the sea atmosphere. Cathodic protection technique is effectively used to mitigate this problem. A predictive model is always required to have an idea about performance of cathodic protection of pipelines and to know the electrolytic effect of seawater on the corrosion resistance of the pipe material. In this study, cathodic protection model of a steel pipeline in marine environment is made using COMSOL Multiphysics software. The design of the pipeline is made in SOLIDWORKS software. Two sacrificial anodes made of three materials i.e. Aluminium, Zinc and Magnesium are used. Seawater environment with an infinite element domain of sea water around the pipe is generated and electrode potentials of the pipe with reference to Ag/AgCl electrode are studied. The potential profile suggests the capacity of the pipe to get corroded. The results from the comparative analysis indicates that Aluminium sacrificial anode provides the best protection of marine pipeline with the maximum potential of 0.965 V vs Ag/AgCl reference. Zinc also provides borderline protection of pipeline. Whereas Magnesium may overprotect the pipeline with such design consideration. Moreover, if protection with Magnesium sacrificial anode is required, the size, the distance and the number of anodes must be adjusted properly to avoid overprotection and reduction of water (which can result in hydrogen gas).