Abstract
One of the major causes of failures in buried pipelines has been identified as microbiologically influenced corrosion (MIC). Globally, the contribution of MIC in total number of buried pipeline failures is estimated to be between 10% to 70%. This research investigated simultaneously two of the most influential factors in corrosion of buried pipelines: bacteria and soil moisture content. All test parameters were chosen based on actual field conditions to have more reliable and attributable results. Sulfate reducing bacteria (SRB) strain, Desulfovibrio desulfurincans, was used for the experiments. Weight loss experiments were carried out using API 5L X65 carbon steel in No SRB and With SRB conditions at three different soil moisture contents in a sandy soil. Results showed that an increase in the soil moisture content decreased the corrosion rate. The presence of SRB in soil, although increased the rate of corrosion and aggravated pitting corrosion at low moisture contents, decreased the corrosion rate at higher moisture contents. At low moisture contents, two layers of corrosion products and at high moisture contents, one layer of corrosion products formed on the surface of specimens. X-ray diffraction (XRD) analysis was conducted to analyze the corrosion products.
