Environmental corrosivity of pipelines and storage tanks

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It is mainly divided into corrosion grades for soil and water. The specific grading criteria are as follows: Classification of soil corrosion grades: For soils in general areas, the corrosion level is determined based on the soil’s electrical resistivity. For example, when the soil resistivity is between 20 and 50 Ω·m, the corrosion level is high ； At 50–100 Ω·m, the corrosion grade is medium ； At 100–200 Ω·m, the corrosion grade is low. For the specific classification criteria, refer to Table 2.0.1; in this table, the soil resistivity is based on the annual minimum value1. Classification of water’s corrosivity level: The corrosiveness of water on the inner walls of pipes and storage tanks is classified based on the annual corrosion rate. For example, when the annual corrosion rate is 0.1–0.2 mm/year, the corrosivity level is classified as high ； At 0.05~0.1 mm/a, the corrosion grade is medium. For the specific grading criteria, refer to Table 2.0.21. Furthermore, the design of anti-corrosion systems should take into account the corrosion levels of the soil and water, as well as various environmental factors, in order to select appropriate anti-corrosion coatings and cathodic protection measures that will ensure the service life of pipelines and storage tanks as well as safe operation.