Zinc Tank Anodes
Zinc Tank Anodes
- Zinc Tank Anodes are used to complement the coating at areas of exposed steel prolonging the life of the coating and structure. Hydrogen is evolved from zinc anodes and thermite sparking may occur when light alloys impact on rusty steel. Therefore there is a height restriction in cargo/ballast tanks in tankers that anodes are not located at a height (in m) greater than 27/W where W is the total mass (in kg) of the anode and insert.
- Zinc anodes has been used as a sacrificial anode material in seawater since 1824, when Sir Humphery Davy used zinc blocks to prevent corrosion of the copper cladding on the hulls of British warships.
- Modern zinc anodes used for cathodic protection are cast from high purity zinc (99.995 %) alloyed with aluminium and silicon to combat impurities and cadmium to give uniform dissolution with loose dispersible corrosion products.
- The most widely used specification for zinc anodes is US Mil Spec 18001J are the most widely used, for cathodic protection.
|Elements||Standard (Wt. %)||High purity Wt. %|
|Copper||0.005 max||0.002 max|
|Iron||0.005 max||0.0014 max|
|Cadmium||0.025 - 0.07||0.003 max|
|Lead||0.006 max||0.003 max|
- Zinc anodes of other compositions are also manufactured by us to suit individual requirements
- Zinc anodes perform reliably in water and mud with resistivities up to 1000 Ohm cm and have a driving potential of 250 mV against protected steel at normal ambient seawater temperatures. This driving potential reduces as the temperature rises and zinc should not be used where temperatures above +50 Deg C are likely to occur.