Apparatus for Studying the Effect of Water Wetting on Carbon Dioxide Corrosion of Mild Steel

Water wetting is a crucial issue in carbon dioxide (CO2) corro-sion of multiphase flow pipelines made from mild steel. This study demonstrates the use of a novel benchtop apparatus, a horizontal rotating cylinder, to study the effect of water wetting on CO2 corrosion of mild steel in two-phase flow. The setup is similar to a standard rotating cylinder except for its horizontal orientation and the presence of two phases—typi-cally water and oil. The apparatus has been tested by using mass-transfer measurements and CO2 corrosion measure-ments in single-phase water flow. CO2 corrosion measure-ments were subsequently performed using a water/hexane mixture with water cuts varying between 5 % and 50%. While the metal surface was primarily hydrophilic under stagnant conditions, a variety of dynamic water wetting situations was encountered as the water cut and fluid velocity were altered. Threshold velocities were identified at various water cuts when the surface became oil-wet and corrosion stopped. KEY WORDS: carbon dioxide corrosion, flow, mild steel, pipelines, water wettin