Corrosion Behavior of 9 to 25% Cr Steels in Wet CO2 Environments

This paper reports the results of an investigation into the effects of various environmental factors on CO2 corrosion of 9 to 25% Cr steel, with emphasis on the finding that each alloy has application criteria based on critical temperatures and CO2 partial pressures in a CO2-Cl− environment. It is also shown that each alloy would be resistant even in two phase flow at flow rates of up to 26 m/s (in the respective critical conditions). The potential corrosion behaviors of 9Cr-1Mo, AISI 420 (13Cr), and 22 to 25% Cr duplex phase stainless steels in severely corrosive wells was investigated using a CO2-Cl− solution with a slight H2S contamination. In particular, the effects of H2S partial pressure and temperature on SCC and localized corrosion of these alloys are discussed.