PILOT STUDY OF A LABORATORY-BASED MICROBIOLOGICALLY INFLUENCED CORROSION (MIC) TEST USING MICROBIOLOGICAL CONSORTIA SAMPLED FROM THE FIELD

Experts widely agree that the verification of microbiologically influenced corrosion (MIC) require the use of multiple lines of evidence (MLOE), including metallurgical, microbiological, operational/historical and
environmental/chemical aspects. Existing standards related to MIC, such as NACE TM0106, TMO212 and TM0194, primarily aim to offer guidance on gathering such evidence. Working Group 5 of Euro-MIC
COST action 20130 (Achieving standardization) proposed a laboratory-based approach that directly confirms the capability of the sampled consortium of microorganisms, obtained from the specific field
location under investigation, to increase and/or alter the corrosion processes. It is necessary to verify this laboratory approach by conducting it in different laboratories, performed by different scientist. In the
current study, the experiments based on the laboratory protocol of WG5 were conducted at Endures’s laboratory using environmental samples (sediment and seawater) from the North Sea. Metal coupons
(carbon steel C1010) were exposed to sediment and seawater samples with varying microbial inoculums and controls over 150 days. Microbial identification, corrosion product analysis, and surface morphology
assessments were conducted using molecular and microscopy techniques. The results indicate distinct microbial influences, particularly in treatments containing yeast, which fostered heightened anaerobic
activity, notably by sulfate-reducing bacteria (SRB). Weight loss measurements and surface analysis revealed elevated corrosion rates and susceptibility to pitting corrosion in microbial inoculum treatments,
with yeast presence exacerbating corrosion processes. Elemental analysis confirmed the presence of iron sulfide in corrosion byproducts, affirming SRB activity. The findings emphasize the importance of
employing a MLOE approach and investigating pitting corrosion to better understand the impact of microorganisms on metal corrosion in the marine environments. This study contributes to advancing
knowledge in the field and developing standardization: the lab-to-field transition for MIC testing.

Keywords: Microbiologically influenced corrosion (MIC), Multiple lines of evidence (MLOE), Achieving standardization, Marine Corrosion.

Acknowledgements:
We would like to express our sincere gratitude to the Euro-MIC Cost Action CA20130 for providing the invaluable opportunity to conduct this Short-Term Scientific Mission (STSM). Their support has been
instrumental in advancing our research in the field of MIC in marine environments. Additionally, we extend our heartfelt thanks to Endures Company for their generous provision of materials and necessary samples
for this study, as well as the scientific advice and technical assistance provided throughout this work. Their expertise and guidance have been indispensable in carrying out the experiments and analysing the results
effectively.