Effect of environmental factors on corrosion behaviour of L360QCS pipeline steel in H2S/CO2 environments

The present research investigated the effect of H2S/CO2 partial pressure, sulphur deposition and corrosion inhibitor on the corrosion behaviour of L360QCS pipeline steel in H2S/CO2 environments by immersion tests, scanning electron microscope analysis and electrochemical measurements. The results show that the corrosion rate (CR) of L360QCS steel decreased first and then increased with increasing p(H2S) and p(CO2). The CR is closely associated with the protectiveness of corrosion film. Sulphur deposition can cause an acceleration of the corrosion of steel in H2S/CO2 environments. Furthermore, the CR increased obviously with increasing p(H2S) and p(CO2) in sulphur deposition environments. After addition of continuous corrosion inhibitor, the CR decreased significantly in H2S/CO2 environments. Prefilming corrosion inhibitor could enhance the inhibition effect in the presence of continuous corrosion inhibitor.