Abstract
The needs of oil and gas operators are challenging the industry to push the limits in sour service materials always further by finding the best compromise between high strength steels and good resistance to Sulphide Stress Cracking (SSC). It is in this context that materials have been recently developed, so as to respond to increasingly severe service with high level of Specified Minimum Yield Strength (SMYS). This communication presents the combination of computational modeling methods, advanced metallurgical characterization techniques, scale-up methods (from laboratory to mass production) for designing sour service steel grades with improved SSC resistance. Basics, pros and cons of several tools are discussed; namely X-Ray Diffraction from synchrotron beam, Transmission Electronic Microscopy, Electron Back Scatter Diffraction, Thermo-Calc™. Their efficiency to optimize design has been validated on a selection of lab casted prototypes and applied to the development of a new 125 ksi SMYS material with enhanced SSC resistance, able to sustain 0.1 bar H2S at ambient temperature. Some results demonstrating the SSC resistance as evaluated with NACE TM0177-2016 Method A of the newly developed steel sampled from pipes already produced at industrial scale will be shown.
