1. Zinc anode system
The zinc anode system is used to protect the storage tank. It is simple to install and will not cause corrosion interference. However, unless the storage tank is well insulated from the pipeline and other systems, the storage tank will not be fully protected. Other systems include pipe networks, instrument connection lines, cable casings, concrete reinforcement and tank group grounding systems. Insulating so many parts is not only expensive, but also has high maintenance costs in the future. Therefore, the system is often ineffective.
The driving voltage of the sacrificial anode system is generally lower than 0.7V, which ensures the current output of the cathodic protection system. Once the storage tank is short-circuited with any of the above parts, it will not only make it difficult to protect the storage tank, but also cause the sacrificial anode system to be exhausted quickly, and the protection life will be short.
2. Zinc anode system
This system is mainly used for already built storage tanks, especially for small areas. Its disadvantage is that the cathodic protection current is uneven and some areas cannot be protected. It is easy to cause corrosion interference. The anode is in very harsh working conditions and is prone to premature damage.
3. Zinc alloy sacrificial anode system
The anode is made of conductive rubber wrapped on the outside of the cable, and a layer of carbon powder backfill is wrapped on the outside of the rubber. The system can be laid under the bottom plate of the tank, the current is evenly distributed, and it is not easy to cause corrosion interference, but it has the following disadvantages:
1. The transportation and installation costs of this system are higher than those of the mesh anode system, and each anode plate is very heavy. It increases the difficulty and cost of handling.
2. The filler belt is easily damaged, resulting in filler leakage and needs to be filled later.
3. Because the conductive rubber is prone to aging and cracking under the action of current over time, it leads to rapid corrosion of the copper core cable, causing the system to fail prematurely. The system cannot be bent excessively.
4. Many cable connections are required on site, and the quality is difficult to guarantee.