On the problems of auxiliary anode and reference electrode

There are two kinds of auxiliary anodes commonly used on ships: attached anodes and concave anodes, which are installed flush with the ship's side. In the past, traction type aluminum anode or platinum silver anode was used, but it was not used due to insufficient protection of the arch part. The biggest advantage of the attached anode is that the grounding resistance is low, which is directly proportional to the protection current, because the actual anode body is composed of thin strips embedded on both sides of the inclined plastic block, and the disadvantage is that the anode body is exposed on the side of the ship and is prone to mechanical damage.


Therefore, two new anode structures have been developed. They are more compact and have a moving surface close to square or circular, but with slightly poor ground resistance. They are flat on one side of the ship, or are installed flush with the side of the ship. In fact, the anode body is a flat anode embedded in a plastic support block with a metal ring around it to weld the anode to the hull.


Such anodes are made of lead silver alloy or platinum titanium plating. Concave anode is mainly used in icebreaker and other high load ships, and is installed in the bow. In this case, additional protection plates should be used. The choice of anodes also depends on the severity, cost and durability of the expected service conditions.


Under a certain voltage, the current output is inversely proportional to the grounding resistance, but is proportional to the conductivity of water, which can be 100 times different. In the water area with poor conductivity, the anode voltage must be increased in order to achieve the required protection current density. It is not possible to exceed the voltage limit of the protective device and the allowable driving voltage of a specific anode.


Therefore, it is necessary to design ships and special types of waters that may have problems in this respect. Short term berthing in port may not be considered, but in high resistance water area, insufficient protection will occur due to voltage limitation.


Shandong Linyi Bosi conductive materials Co., Ltd. is a high-tech enterprise specializing in the production of MMO flexible anode, conductive polymer flexible anode and titanium coated anode, mainly providing cathodic protection technology, engineering design, installation and technical services.