Predicting the Performance of API 5L-X65 in CO2 Erosion-Corrosion Environments Using Design of Experiments

The performance of API-5L-X65 in saturated-CO₂ erosion-corrosion environments was studied using a Box–Benhnken design of experiments with three important variables; sand loading, velocity and corrosion inhibitor concentration. These variables were studied at low, intermediate and high level, referred to in this  study as -, 0, + respectively. This methodology not only allows the assessment of each individual parameter on the total weight loss (TWL) but also the interaction of those parameters on the total damage caused by erosion and corrosion by developing a statistical model. Moreover, the variables which have the greatest effect on the performance of material, and optimization of variables on TWL can also be identified. The change of current density as a  function of  sand loading at different velocities was also  examined. Post surface analysis  using optical, SEM, and XRD  has been  conducted  to enable the degradation mechanisms to be studied. In-situ electrochemistry was carried out to assess the effect of sand loading and corrosion inhibitor and sand loading at different flow velocities. The paper presents the statistical evaluation of erosion-corrosion damage in addition to a mechanistic study.