Study on Multivariate Synergistic Corrosion Behavior and Corrosion Prediction Model of X65 Steel

Abstract

The risk of corrosion failure of submarine pipeline increases sharply，and it is necessary to study the corrosion behavior and corrosion rate of submarine pipeline.In this work，18 groups of six factors and three-level orthogonal experiments were carried out for the submarine pipelines commonly used steel X65 steel in high temperature and high pressure reactors.The synergistic corrosion behavior of X65 steel by CO2，H2S，pH value，Cl-，temperatures and flow rates was studied，and the main controlling factors for corrosion were determined as CO2partial pressure ＞H2S partial pressure ＞Cl-concentration ＞pH value ＞flow rate ＞temperature.From the results of scanning electron microscope，the synergistic corrosion behavior of H2S，CO2and Cl-was clarified: CO2formed dense FeCO3，which was located at the bottom of the corrosion product film，and the surface was Fe sulfide.Moreover，Cl-passed through the corrosion product film to promote the occurrence of corrosion.Finally，based on the orthogonal experimental data，a six-factor corrosion rate prediction model was established，and the prediction model error was less than 20%.

Keywords

• x65 steel|co2|h2s|corrosion prediction