Effect of soil particle size on the corrosion behavior of natural gas pipeline

• Effect of corrosion on pipeline steel in soil environments, with different particle sizes
• Illustration of the influence of particle size on steel corrosion behavior, using the concept of gas/liquid/solid TPB zone
• The cathode oxygen reduction process is accelerated, with decreasing particle size.
• The corrosion rate of pipeline steel increased with the particle size decreasing.
• Sample surface significance analysis indicated more severe corrosion with small particle size of sandy soil.

In this study, the effect of soil particle size (0.1–0.25 mm, 0.6–1.0 mm) on the corrosion behavior of natural gas pipeline was investigated by electrochemical technology. The results indicated that the polarization resistance of pipeline steel decreased with decreasing particle size. For all polarization curves, the right shift of cathodic branch with decreasing particle size, suggests that the cathode oxygen reduction process is accelerated. The corrosion of steel is controlled by the process of cathode diffusion and oxygen reduction. This can be attributed to the effect of gas/liquid/solid three-phase boundary (TPB) zone on cathodic process of pipeline steel, and the corrosion rate is mainly determined by the cathodic reaction. The corrosion rate of pipeline steel increased with decreasing particle size.