Bio-corrosion on steel structure (ASTM A106 and A53) in marine environment

Abstract

Background: Corrosion is the phenomena on the offshore structures which is impossible to be avoided. Corrosion is occurred by physical, chemical and biological process. Generally, biological corrosion is caused by presence of microbes, which on its process can be individual or make a new colony with other bacteria. Methodology: This study were to determine the corrosion rate on 2 types of steel structures (ASTM A106 and A53) in deep seawater (salinity of 33‰), medium seawater (salinity of 35‰), shallow seawater (salinity of 37‰) and to determine bio-corrosion rate was caused by 3 species of bacteria Escherichia coli, Pseudomonas fluorescens and Thiobacillus ferrooxidans in three salinity (33, 35 and 37‰). Results: The results showed maximum corrosion rate, without bacteria of ASTM A106 and ASTM A53 at day 10 in salinity of 33‰ were 0.5797 and 0.6173 mm year−1, respectively. It indicating that ASTM A106 had a better corrosion resistance level compared with ASTM A53 in marine environment. The T. ferrooxidans caused the highest bio-corrosion rate (1.3212 mm year−1) in salinity of 33‰ compared with bio-corrosion rate by E. coli and P. fluorescens on ASTM A53. Meanwhile, the maximum bio-corrosion rate by T. ferrooxidans on ASTM A106 was 1.253 mm year−1. Conclusion: The bio-corrosion rate on ASTM A53 increased by two-fold compared with the condition without bacteria addition (corrosion rate of 0.6173 mm year−1).