Life prediction and reliability analysis of pipe steel used for oil transportation when exposed to Cl^- and CO<inf>2</inf> solutions under flow conditions

One of the most reliable forms of fluid transportation like oil and gas among others is using steel pipelines. An experimental set up comprised of API X-52 steel samples exposed to Cl- and CO2 solutions under different flow conditions were used to analyze structural safety of this material under simulating pipeline working conditions. Corrosion rates were calculated from the electrochemical impedance spectroscopy technique and expected life is estimated by reliability analysis method, applied for laboratory conditions of steel exposed in brine solution with different CO2 compositions and different flow rates. The expected lifetime of the material subjected to flow rotation decreased when higher concentrations of CO2 were present in the electrolyte. The expected time for a failure assuming that the metallic structure is under operation conditions is short for higher rotation rates, which is equivalent to higher linear flow for a pipeline structure.