A comparison of flow velocity influence on localized corrosion of 13Cr, S13Cr and Super Duplex stainless steel on oil production condition

摘要

The advancement in oil exploration makes research and development in the field of materials engineering necessary to ensure good performance of the materials during the longest possible period of operation. Without sacrificing safety, the cost of materials is of the utmost importance for designing projects in the oil industry. Super Duplex stainless steel is one of the noblest steels in its class, and one of the most expensive. Studies propose the use of other Fe-Cr alloys as Super Duplex substituents, one of them being the 13Cr alloys with Molybdenum additions, called S13Cr. Both Super Duplex and S13Cr have high resistance to generalized corrosion, however they may be susceptible to localized corrosion and, therefore, further studies are necessary to evaluate, specially the influence of shear stress in this process. This work aims to compare the influence of flow on the tendency to localized corrosion of four different alloys in aggressive environment simulating petroleum production and to investigate the existence of a critical pit velocity using the technique of Rotating Cage. The preliminary results showed a crescent number of pits with the increase of flow speed to 13Cr and 13Cr2Mo and additionally to the former the pits morphology was affected as well. To 13Cr2.5Mo and 25Cr presented similar behavior and few pits detected only at 1200 RPM.