Cathodic polarization has been established as the most effective control system of corrosion in
buried or submerged pipelines; this happens even in presence of sulfate reducing bacteria (SRB), only
if the polarize potential reaches values of -0.950 V vs Cu/CuSO4. The purpose of this investigation was
to evaluate the effectiveness of cathodic polarization of steel API 5L 42X exposed to a mixed SRB
strain isolated from a brackish water lake, using microbiological, electrochemical and microscopic
analysis. The experimental design consisted in performing diverse studies using the cell developed by
Devanathan and Starchursky and varying the applied potential from -1.3 to -2.1 V vs. Cu/CuSO4, during
exposure time (72 hours). Different blank test were done without polarization to compare and observe
its effects. The results obtained demonstrated that a polarize potential of -0.950 V vs Cu/CuSO4 is not
enough to protect the steel in environments with SRB, even when polarized potentials equal to -1.37 V
vs Cu/CuSO4 were reached on the metallic surface.