Calculate:
1-The number of required anodes of (Zn and Al)?
2- The suitable anode(e.i. Zn or Al)?
above back to the structure which be protected with a sacrificial cathodic protection system with a life time of 5 years, where planned to place an uncoated steel drilling platform in the sea. wetted surface area is 3000m ^ 2 current required for uncoated steel is 100mA / (m ^ 2) volume wastage rate of Al is 1.518 * 10 ^ – 3 * m ^ 3 / A year Zn 1.18 * 10 ^ – 3 m³/A.year. Current density of both Zn and Al is 6.5A / (m ^ 2) one anode is cylindrical shape with daimeter (60) mm, long(450) * mm .