Corrosion Behavior of Low Carbon Line Pipe Steel in Soil Environment

Abstract

Some operating buried transmission pipeline systems will develop unforeseen surface corrosion. Electrochemical corrosion behavior of low carbon line pipe steel in NS 4 soil test solution has been investigated by EIS method. Corrosion phenomenon is accentuated by influence of such soils parameters as specific resistance, pH, temperature, moisture content and chemical composition of electrolytes contained in soil. Results showed that steel corrosion increases considerably at acidic pH environments. Corrosion current density increases with temperature in the range from 20 to 60 °C. The associated activation energy has been determined. Impedance curves showed that the charge transfer resistance ( R t ) increases with increasing immersion duration. Parameters such as corrosion current density ( I corr ), polarization resistance ( R p ), soil specific resistance (r) can serve as the parameters for evaluation of soil corrosiveness.