Flow Corrosion of Defect Pits with Different Depths in Co2 Saturated Solution

Abstract

Aiming at the local pitting corrosion problem in oil and gas transmission pipelines, a multi-field coupled finite element model was constructed to simulate the flow corrosion of artificial defect pits with different depths in CO2-saturated NACE solution. Based on the electroneutral mechanism model of supporting electrolyte solution, the coupling between the macroscopic flow field solved by the standard k-ɛ turbulence model and the electrochemical corrosion mass transfer process was achieved. It was found that the local flow characteristics of the pits changed the concentration distribution of corrosion substances. The maximum concentration of corrosion products Fe2+ in the pits appeared at the upstream pit wall, while H+, which affected the corrosion rate, gathered at the downstream pit mouth. The flow state of pits with different depths is different, and the interaction between the turbulence intensity at the pit mouth and the reflux velocity in the pit affects the mass transfer process in the pit.

Keywords: Artificial pitting pit, Multi-field coupling model, k- ɛ Turbulence model, Flow corrosion, Turbulent mass transfer