anticorrosion measures

   Water transport is one of the five major transportation systems, and ships are the main tools for water transportation. However, due to the long-term navigation of ships in the ocean, corrosion occurs to varying degrees by the erosion of various corrosive media. At present, the ship's anti-corrosion measures are mainly a combination of paint coating and cathodic protection. As the coating will inevitably exist in the process of painting and use of leakage, pore and other defects, corrosion will first arise in these places, accelerated and caused by pore corrosion, applying cathodic protection can effectively inhibit pore corrosion of the coating defects, but also reduce the current density of cathodic protection, so that cathodic protection is more economical, the protection of a more uniform distribution of the current, the effect of protection is better.

    For large ships, a relatively high protection current is required, in which case two separate protection systems can be installed, placed in the middle of the ship, or arranged near the head and stern of the ship. The constant potential meter can be installed in or near the main control room in the cabin. The installation of the constant potential meter should pay attention to its cathode ground and the reference electrode zero ground can not be common point, to be separated by a certain distance. The negative pole of the constant potential meter should be connected to the ship's hull, and the positive pole should be connected to the auxiliary anode which is insulated from the ship's hull, and must not be connected inversely.

     The installation of marine auxiliary anode usually has two forms, one is attached type and the other is recessed type. The advantage of attached type is that the current dispersing ability is better; the disadvantage is that it is easy to be damaged. The advantage of concave type is that the anode is not easy to be damaged, but the dispersing ability is not as good as attached type. Recessed anodes are mainly used on icebreakers, which are highly loaded ships, and are installed in the bow part of the ship.

    The longitudinal arrangement of the reference electrode should depend on the number of reference electrodes, if the whole ship uses two reference electrodes, one is configured in the bow and one in the transom or the middle of the ship, and it is better to be separated from the port and starboard sides. If more than one reference electrode is installed, the bow, middle and stern can be configured, and the port and starboard sides are distributed. The reference electrodes are arranged in the middle of the two auxiliary anodes, or they can be arranged in the furthest place from the anodes, i.e., installed in the place with the most positive potential. The reference electrode is arranged vertically and should be on the same level with the auxiliary anode.