Microbiologically Induced Corrosion (MIC) is a potential threat associated with hydrotesting. It
has been established that Sulfate Reducing Bacteria (SRB) can utilize hydrocarbons or even
live on CO2 – H2 autotrophically. Pitting due to MIC during hydrotesting itself may not be a
serious problem, because its duration is limited to several days or months. The biofilms left
behind after the hydrotest may present a serious threat once the pipelines are commissioned
and used for many years, because pipeline fluids may contain a sufficient amount of nutrients
for biofilms to flourish. This laboratory investigation was conducted to study the MIC threat in
hydrotests using seawater. Arabian and Gulf of Mexico (GoM) seawater samples were
collected from offshore locations. Quantitative PCR (Polymerase Chain Reaction) analysis was
used to detect SRB in seawater samples. It was found that offshore GoM “clean seawater” did
not contain a sufficient amount of organic carbons to support the rapid growth of biofilms.
Enriched seawater spiked with SRB was used to speed up biofilm growth. An MIC prediction
software program based on the mechanistic Biocatalytic Cathodic Sulfate Reduction (BCSR)
theory was able to predict longer term SRB pitting using short-term pitting data in laboratory
experiments for MIC in hydrotest.
Keywords: hydrotest, SRB, MIC, seawater, THPS, model