Effects of flow velocity on the corrosion behaviour of super 13Cr stainless steel in ultra-HTHP CO2–H2S coexistence environment

The corrosion behavior of super 13Cr SS under the effect of flow velocity in the ultra-HTHP supercritical CO2–H2S–Cl- environment was investigated. The results show the morphology and composition of the corrosion products of super 13Cr SS samples change with varying flow state. In the static condition, the layer consists of an inner layer of Cr(OH)3, a middle layer of Fe1−xS, and an outer crystalline FeCO3 layer. However, in the dynamic supercritical CO2 phase, a galvanic couple effect exists between the pyrrhotite and uncovered steel. Meanwhile, the velocity delays the deposition of FeCO3 and promotes the development of pitting.