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In real production life, for some equipment, especially mechanical equipment, manufacturers often do relevant anti-corrosion treatment, and this anti-corrosion treatment does not simply mean preventing the product from rusting, but also has other anti-corrosion effects, and sacrificial anode is the most representative anti-corrosion material. So, what exactly is a sacrificial anode? What are the common sacrificial anode protection materials?
According to industry experts who specialize in the research and development and production of aluminum alloy anode products in the region, the composite sacrificial anode is composed of magnesium-coated zinc, and the high driving potential of the magnesium anode is used to meet the requirements of the initial cathode polarization of the pipeline. The high current efficiency of the zinc anode is then used to extend the service life. Sacrificial anodes are usually only economically used in structures with small protection current requirements and in low soil resistivity environments. In addition, they are only valuable when there is no power supply or uneconomical conditions occur.
For now, the common sacrificial anode protection anode materials in actual applications are mainly the following:
1. Aluminum sacrificial anode: mostly used for cathodic protection of metal structures in seawater environments or bottom plates of crude oil storage tanks. Its electrode potential is -1.05VCSE.
2. Magnesium sacrificial anode: Magnesium anode can be used in soil or freshwater environment with resistivity of 20 ohms. m to 100 ohms. m. The potential of high potential magnesium anode is -1.75VCSE, and the potential of low potential magnesium anode is -1.55VCSE.
3. Zinc sacrificial anode: Zinc anode is mostly used in soil environment or seawater environment with soil resistivity less than 15 ohms. m. Electrode potential -1.1VCSE.
4. Backfill: When filler is used, the current output efficiency of the anode is improved. If the anode is buried directly in the soil, the anode itself will corrode due to the uneven composition of the soil, thereby reducing the anode efficiency. The role of filler: First, to retain moisture and reduce the grounding resistance of the anode, and second, to make the anode surface corrode evenly and improve the utilization efficiency of the anode.
5. Strip anode: In order to reduce the grounding resistance of the anode, strip magnesium anode or zinc anode is sometimes used. The anode belt is laid along the protected structure to make the current distribution more uniform. When the anode belt is laid along the pipeline, it should be connected to the pipeline once every certain distance. The spacing should not be too large, because as the anode is consumed, the cross-sectional area continues to decrease, and the anode belt resistance will gradually increase. In order to reduce the voltage drop along the anode belt, the connection interval is generally not more than 305 meters. The general specifications of the strip anode are 19x9.5mmx305m per roll.
