A new 13Cr martensitic stainless steel (0.025C-13Cr-Ni-Mo) with excellent resistance to CO2 corrosion and good resistance to SSC is developed and its application limits in oil and gas environments
is clarified. The CO2 corrosion rate of the 13Cr steels with Ni and Mo is less than 0.3 mm/yr at 180°C (356°F ) in 20% NaCl. It is less than that of the conventional 13Cr steel (0.2C-13Cr). The corrosion rate of the steel slightly decreases with the increase in Mo and Ni content. The SSC resistance improves with the increase in Mo content. The critical partial pressure of H2S for the 2% Mo steel is greater than 0.005 MPa at the pH value of 3.5. The effects of Ni and Cu on SSC are not distinctive for this kind of steel. These results depends on the hydrogen permeabiIity. The critical H2S partial pressure for the 110 grade steel is the same as that of the 95 grade steel at the pH values of 4.5 and 3.0, and is slightly lower
at the pH values between 3.0 and 4.5. The new 13Cr steel proves to have excellent properties in the sweet and slightlyt sour environment.
Keywords: martensitic stainless steel, seamless pipe, OCTG, carbon dioxide corrosion, sulfide stress cracking