Interaction between local corrosion and flow field of natural gas long-distance pipeline by artificial rectangular defect pit

The corrosive environment in long-distance natural gas pipeline was simulated by the online high shear stress flow test platform. The interaction between flow fields and local corrosion in different local corrosion stages was studied by machining different depths rectangular defect pit (RDP) on X80 pipe steel specimens. The electrochemical signals of each specimen under high shear stress flow were measured online using an integrated three-electrode and electrochemical system. Raman spectroscopy confirmed that the corrosion scale of X80 pipeline steel in CO₂-saturated National Association of Corrosion Engineers solution was composed of FeCO₃. The scanning electron microscope images displayed variations in microstructure of the corrosion scale at different RDP depths and different areas. The flow field fluctuations induced by RDP were analyzed by computational fluid dynamics simulations and the development of local corrosion pits was discussed in terms of integrity of corrosion scale, convective mass transfer, and diffusion mass transfer.