Effect of SO2, NO2, O2, and Chloride on Corrosion Behavior of Duplex and Super Duplex Stainless Steels in CCUS Environments

Paper ID: C2025-00068 ABSTRACT: To significantly reduce CO2 in the atmosphere, CO2 must be captured, compressed, and transported to a sequestration site for permanent storage. When injecting CO2 emitted from various industrial sources into a well, injected fluid and formation water will be saturated with CO2 with corrosive impurities. Corrosion resistant alloys are candidates for injection tubing. The objective of this work is to evaluate the effect of SO2, NO2, O2, and chloride concentrations on the duplex and super duplex stainless steels in the aqueous phase under supercritical CO2 environment. Samples were exposed in 5 or 25 wt% NaCl were carried out at 150°C with 120 bar (1740 psi) CO2 in a 7L autoclave. Up to 200 ppm of SO2, NO2, O2 were introduced into the autoclave. The samples were examined for uniform and localized corrosion. Up to 100 ppm SO2, both stainless steels showed good corrosion resistance. However, with 100 ppm NO2, crevice corrosion was observed on the duplex stainless steel. When O2 was introduced in addition to NO2, super duplex stainless steel also showed signs of crevice corrosion. The localized attack further intensified with higher chloride concentration. Compared to pitting and uniform corrosion, crevice corrosion should be emphasized in such an environment.