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In today's industrial production, sacrificial anodes are the most widely used corrosion-resistant products. They are often used on the seafloor and in soil, and they do not cause water pollution. However, there are many different types of sacrificial anodes available today. So, how familiar are you with the sacrificial anode packaging layout? Let's take a look at the following introduction.
1. Sacrificial Anode Packing Materials
Chemical packing materials are composed of various ingredients. Some formulations contain high levels of soluble salts. These salts dissolve in water, reducing the packing volume. While initially effective, the grounding resistance of the sacrificial anode bed gradually increases as the salts dissipate. Gypsum powder is a key ingredient for improving the performance of Zn and Mg sacrificial anodes, activating them and ensuring uniform dissolution. A sufficient amount is crucial. Therefore, years of empirical research have proven that the optimal packing material formula for magnesium and zinc sacrificial anodes is the following weight ratio: gypsum: bentonite: sodium sulfate = 75:20:5.
II. Sacrificial Anode Arrangement
Sacrificial anodes can be buried singly or in groups. Due to the mutual influence of the electric field, the combined current generated by several sacrificial anodes in a group is significantly less than that generated by a single sacrificial anode, resulting in low sacrificial anode utilization. Arranging sacrificial anodes in groups increases the spacing between them, affecting the uniformity of the protection potential distribution. Arranging sacrificial anodes in separate groups improves sacrificial anode utilization and achieves a more uniform distribution of the protection potential due to the reduced spacing between them. This has proven to be superior to grouping.
III. Use of Magnesium Strip Sacrificial Anodes
Magnesium strip sacrificial anodes are made of high-purity magnesium or a magnesium-manganese alloy and have a negative potential (-1.7V). They are used in environments with high soil resistivity, such as soils greater than 100Ω.m. They weigh 0.37 kg/m each and, due to their large surface area per unit weight, generate high current. The current output is as follows: for a soil resistivity of 50Ω.m, the output current is 10 mA/m; for a freshwater resistivity of 150Ω.m, the output current is 3 mA/m. Therefore, it is not suitable for environments with low resistivity because it consumes too quickly. Whether magnesium ribbon can be used for conveying pipes within casing depends on the resistivity of the medium inside the casing. If the resistivity of the medium entering the casing is low, the ribbon sacrificial anode will consume too quickly and have a short lifespan. Block sacrificial anodes are preferable, as they have the same lifespan as the outer pipe and are less expensive. Magnesium ribbon can be used for temporary protection or to pre-polarize the steel surface with the help of the short-lived magnesium ribbon.
