High Cr Stainless Steel OCTG with High Strength and Superior Corrosion Resistance

New martensitic stainless steel pipes (HP13Cr, UHP15Cr) which improve the CO2 corrosion resistance and sulfide stress corrosion (SSC) resistance of API13Cr were developed and their application limits were clarified. The composition of the products features low C and addition of Ni and Mo. CO2 corrosion resistance was greatly improved by adopting a high Cr, low C composition design, while SSC resistance was substantially improved by Mo addition. The critical temperature for HP13Cr in high CO2 environments is 160DGC. UHP15Cr has high strength, with Yield strength (YS) exceeding 861 MPa, and can be used in high CO2 environments at temperatures up to 200DGC. These new martensitic steel pipes show excellent properties in sweet, high temperature, high COa environments and slightly sour environments containing small amounts of H2S where conventional 13Cr pipes could not be used.