The Effect of Particle Size on the Electrochemical Corrosion Behavior of X70 Steel in NaCl Contaminated Sandy Environment
Corroded soil is a complex material consisting of soil particles, pore fluid, and pore gas. The behavior of buried pipelines in a corrosive soil is influenced by not only fluid, gas, but also particle sizes. However, the effect of soil particle size on the electrochemical corrosion behavior of steel pipelines in a corrosive soil system remains unknown. An indoor experiment is conducted. Three sorts of uniform sands and two sorts of grade sands contaminated by sodium chloride are used as a contaminated environment in this experiment. Steel disc buried in the contaminated sand is a type of pipeline steel, grade API 5L X70 (for short X70). The results from uniform sands tests show that the corrosion behavior of X70 steel is greatly affected by the particle size and distribution. The corrosion rate decreases first then increases with the soil particle size increasing for the uniform sandy environment. This implies that there is a critical particle size. The corrosion rate of X70 steel in the poor gradation sandy soil environment is significantly larger than that in the well grade sandy soil environment. The experimental results provide that the electrochemical impedance spectroscopy (EIS) is an effective way to evaluate the corrosion of soil environment.
KeywordsSodium chloride contaminated sandy Particle-size EIS X70 pipeline steel
The authors thank the supports of National Natural Science Foundation of China (51178287, 51208333) and Youth Foundation of Taiyuan University of Technology (1205-04020203).
- 2.Zhou, H., Li, Q., Zhu, R.: Saline soils’ characteristic of engineering geological in Ku’erle, Xinjiang Province. West-China Explor. Eng. 2000(3), 37–38 (2000)Google Scholar
- 3.Jin, M., Meng, X., Huang, H., et al.: Corrosion mechanics of carbon steel in four types of soils. J. Huazhong Univ. Sci. Technol. (Nature Sci.) 30(7), 104–107 (2002)Google Scholar