Corrosion Inhibition of Deposit-Covered X80 Pipeline Steel in Seawater Containing Pseudomonas Stutzeri

Abstract

Under-deposit corrosion, a typical corrosion style, leads to the pipeline steel corrosion in the marine environment. The under-deposit corrosion behavior and mechanism are still needed to be do futher investiagation especially with the participation of microorganisms. In this work, corrosion inhibition of deposit-covered X80 pipeline steel caused by Pseudomonas stutzeri in seawater coatining CO2 was investigated using weight loss, electrochemical measurements, wire beam electrode and surface analysis. Results show that steel corrosion declined fast due to the covered deposit no matter whether with and without P. stutzeri, but the corrosion rates were smaller with the assistance of P. stutzeri. The biggest corrosion rates were (0.365 ± 0.021) mm/y and(0.230 ± 0.001) mm/y in the abiotic and biotic conditions, respectively. The corrosion inhibition efficiency of P. stutzeri had a decrease because of the deposits leading to a low biological activity. The galvanic current density between deposit-covered and bare specimens in seawater was weakened by P. stutzeri, and then caused a slight corrosion especially pitting corrosion.

Keywords: Microbiologically influenced corrosion, Under-deposit corrosion, Pseudomonas stutzeri, Corrosion inhibition, X80 pipeline steel