Disc aluminum alloy sacrificial anode

One structural characteristic of offshore platforms is the extensive use of large cylindrical components welded together. The intersection of these cylinders forms nodes. These nodes are high-stress areas on the platform, and in addition to stress concentration, they are likely to simultaneously have factors that promote fracture, such as welding residual stress and welding defects. Furthermore, the complex shape of welded nodes makes them difficult to protect, and other parts of this structure are prone to pitting corrosion and corrosion in the heat-affected zones of welds. Experience shows that severe corrosion phenomena on offshore platforms mostly occur under conditions of no protection, failed protection, or insufficient protection.

Ship ballast water tanks are subjected to harsh corrosive environments with frequent alternations between empty tanks and seawater ballast, resulting in dry and wet cycles. Additionally, the structure of ballast water tanks is relatively complex, with sediment deposition, difficulty in cleaning and drying, and challenges in maintenance, making their corrosive environment extremely severe. The main cause of corrosion in ballast tanks is the electrochemical reaction that occurs on submerged steel plates. For safety reasons, sacrificial anode cathodic protection is generally used instead of impressed current cathodic protection.

Sacrificial anodes for cathodic protection in seawater ballast tanks are made of zinc alloy or aluminum alloy. When selecting these anode materials, both material cost and protection effectiveness should be considered comprehensively. Generally, for providing the same protective current, the price of aluminum alloy is only two-thirds that of zinc alloy. Aluminum anodes have a higher driving potential, providing a larger initial current, which is beneficial for allowing them to enter the secondary bulkhead cathodization. When the humidity inside the tank is high, the impact of anode byproducts on the surface humidity of the bulkhead may not be very significant.

Ship ballast water tanks are areas of severe corrosion on ships and a major factor affecting the service life of vessels. Corrosion in ballast water tanks directly impacts the safe navigation of ships. Additionally, corrosion in ballast tanks significantly increases maintenance costs. The use of aluminum alloy sacrificial anodes in ballast water tanks has significantly reduced the corrosion rate, effectively eliminating ship corrosion, extending the effective service life of vessels, reducing maintenance expenses, and creating more economic benefits.