Research on External Corrosion Mechanism of Buried Metal Pipeline of Oilfield

Taking external corrosion of pipelines as a research point, laboratory test, site verification and spectral analysis were adopted to investigate the corrosion of saline-alkali soil environment in north China. Orthogonal simulation experiments with 9 factors and 3 levels were designed based on physical and chemical test results of local soil, taking 9 main corrosion factors as variables. Standard corrosion test slices of 20# steel were used to perform kinds of physical and chemical experiments for simulating local soil. Analysis of variance was done to these test results. The affecting rule on corrosion rate of soil was researched, and importance degree order of corrosion factors in this district was obtained, namely, Na+>moisture content>temperature>Ca2+>porosity>pH value>SO42->HCO3->Cl-. Furthermore, the main components of corrosion products were analyzed by X-ray fluorescence and compared with the corrosion products of site test slices. From these results, the main components of both corrosion products were consistent basically, but the contents were a bit different, which validates the reliability of laboratory test results to a certain extent.