Some Technical Points about Cathodic Protection of External Surface of Steel Oil Tank Bottom

Cathodic protection can effectively control the electrolchemical corrosion to a tank bottom. Compared with conventional cathodic protection, thete are several points worth of being discussed; l. Tank grounding.Conventionally, the materials of grounding electrodes and the tank body are different, the two kinds of metal make the original battery corroded thus aggrevating the tank corrosion. It is suggested that the grounding material be replaced by zinc or megneseoum; 2. Measurement of potential distribution at the tank bottom. For new tanks, cathodic protection system should be taken into account during the design phase; And for existing tanks, a hard plastic tube with holes in the wall can be applied. The referential potential can be inserted into the tube for mobile measurement; 3.High potential protection of insulated flanges. Three present efficient measures can be adopted: zinc grounding with battery for protection, diode protection and lightning arrester protection; 4. Design parameters. 6-10A/ m² is suitable for current density protection considering the initial and later phases. Several suggestions are given in the paper in accordance with the situation that tank cathodic protection has not yet been put into the conpulsary practice, several suggestions are given for stable practice of the technique.