The process of corrosion of galvanized products in the soil
Corrosion of zinc coating in the soil due to its heterogeneity is usually different. The degree of change is directly dependent on the amount of minerals in the kidney, their nature, the amount of water, oxygen and chlorides, the pH parameter. Corrosion in soil with damaged structure is faster.
The soil with a high content of lime and Sandstone is much more aggressive in contrast to the one in which the content of clay and clay-lime mixture prevails.
Steel structures produced using hot-dip galvanizing, which pass through soils of various types, are subject to corrosion in anode areas. That is why for a certain purpose structures, for example, in order to strengthen the soil, use additional protection in the form of backfill.
Since elements with corrosion mainly appear at the boundary of the transition of soil to air or soil to groundwater, which increases the rate of corrosion, such places require increased protection. The use of cathodic protection for products placed in the soil can reduce the development of corrosion and increase its service life.
The average value of corrosion for the year of zinc coating in the soil is 10 microns, which means that galvanization with hot technology allows to provide high-quality and long-term protection.
We have made a diagram to reflect the effectiveness of galvanizing in soils according to world data. Thus, our company received the following types of dependencies, reflected in the diagrams:
The main feature of the classification is the amount of chloride. 1 and 2 the diagram applies to soil with chloride above 20, and 3 and 4 in the bottom row below 20. Having defined this parameter for soils with a high content, go to the next parameter – humidity. Figure 1 is used for soil with a level of this indicator less than 17.5%, figure 2-more than 17.5. For soil with a low amount of chloride, the next classification parameter is the pH level. Figure 3 applies to soils with pH levels above 7.0 and 4 to pH levels below 7.0.
All charts use the blue line to show the average number of soils that have been considered in different groups to obtain the average characteristic. Green line marked the best variant of the soil in the subspecies, while red-the worst. The shaded areas show how the pH and humidity levels change, affecting the duration of operation. Also, based on the information presented in the diagrams, it can be seen that the average life time of galvanized products in aggressive soils reaches 30 years, and in the best cases – 120 years.