Cathodic kinetics of API X70 pipeline steel corrosion in H 2 S containing solutions under turbulent flow conditions

A study has been carried out on the effect of hydrodynamics, temperature and hydrogen sulphide (H2S) concentration on the corrosion of API X70 steel in a flowing 3 wt-% sodium chloride (NaCl) solution. Potentiodynamic polarisation curves were used to characterise the corrosion behaviour of X70 pipeline steel in 3 wt-%NaCl solutions with H2S concentrations 0, 100, 650 and 2550 ppm at two temperatures, 20 and 60°C, and at turbulent flow conditions. To control flow conditions, the rotating cylinder electrode (RCE) in turbulent flow regime (100–5000 rev min&minus1) was used. It was found that the measured cathodic current is influenced by flow and therefore by a diffusion component. By comparing the theoretical and experimental cathodic currents, the H+ reduction reaction is proposed as the main contribution to the total measured cathodic current density.