On the Requisites for Cathodic Protection of Buried Steel Pipes in the Presence of Sulfate-Reducing Bacteria

Abstract

Laboratory free corrosion tests and cathodic protection tests were carried out to investigate requisites for achieving complete cathodic protection on the steel pipes buried in the microbially active soils containing sulfate-reducing bacteria (SRB, Desulfovibrio desulfuricans) with other species of bacteria. Off-potentials were changed over a range from -0.7 to -1.3V (vs. Cu/CuSO4). The results obtained can be summarized as follows: (1) Comparative free corrosion tests between non-sterile and sterile systems clearly revealed that the presence of SRB can be stimulatory to soil corrosion, (2) Practical sufficient protection in active SRB clayey soil was shown to be obtainable at the off-potentials more negative than -0.9V and/or under the cathodic current densities of not less than 0.05Am-2. (3) The hydrogenase activity of SRB was shown to be active even under the cathodic protection conditions and playing an important role in the protection process by stimulating the formation of protective sulfide films. © 1994, Japan Society of Corrosion Engineering. All rights reserved.