Effect of electrochemical properties of Seoul city's soil on stainless steel

摘要

We investigated how the electrochemical properties of soil have an effect on corrosion of stainless steel; which is one of the major materials for the water mains in Seoul. We embedded seven kinds of stainless steel pipes, STS254SMO, STS2205, STS304, STS316L, STS329LD, STS444 and STS470FC, at a depth of 152m from the ground's suface at eight different sites around Seoul in 2010. The stainless steel pipes were excavated and examined in 2015. The electrochemical properties such as resistivity, conductivity, chloride, sulphate, water content, pH, redox potential were evaluated based on the Korean manual for managing old water mains. This study showed that the resistivity, amount of ions(chloride and sulphate), conductivity, and redox potential are major factors leading to the corrosion of stainless steel in the eight test sites whereas the pH and water content had relatively small effects on the corrosion process. In addition it was noted that soil particles had penetrated the stainless surface at the site with highest ion values and highest conductivity.