Thread Content
Based on the previous background regarding sacrificial anode protection for pipelines and storage tanks, the common causes of failure can be divided into four categories: mismatch between the selected anode type and the environment. In soils or seawater with low electrical resistivity, the driving potential of magnesium anodes is too high, resulting in a consumption rate that far exceeds their designed lifespan； In marine mud areas, the use of ordinary seawater-grade aluminum anodes leads to failure, as the insufficient driving potential prevents proper current output. Material and construction defects: Impurities such as iron in the anode are present in excessive amounts, leading to the formation of micro-cells that cause self-corrosion; a large amount of current is dissipated internally before it can reach the object to be protected ； Insufficient backfilling and wetting of the packing material powder results in the formation of a dense passivation film on the anode surface, causing a sharp drop in the output current. Current leakage and connection faults: Leakage at the insulated joints, improper overlapping of bushings, cause a large amount of protective current to flow into adjacent grounding grids or other metal structures, forcing the anode to be overloaded and deteriorate rapidly ； The cable connecting the anode and the object to be protected is loose or broken, the loop resistance exceeds 1Ω, and the effective output current is almost zero. Lack of environmental management and maintenance: During the rainy season, the soil resistivity drops sharply while the chloride ion concentration rises significantly, causing the anode’s output current to exceed the designed values and accelerating dissolution ； Due to the lack of periodic potential inspections for a long time, the protection deficiencies remained uncorrected, corrosion recurred in certain areas, and the overall protection system failed.