The current density of cathodic protection can vary from A few μA/ Rn2 to hundreds of μmA/m2.

Equalization protection: equalization protection is the use of cable or galvanized flat steel will be the same trench laying, close to the interval parallel or cross direction of the protected pipeline, as well as non-welding connection of the unified bar to be protected between the electrical connection, to achieve the purpose of equalization of pipeline potential.

(1) Impressed current system rectifier: each anode ground bed is powered by a 75A/75V potentiostat. Combined with the protection area given in "Protected Object", the required protection current of plant pipelines is calculated as: I=2.5i×s=2.5×7×10.5=1838

(2) Selection of protection current density and calculation of protection current: Applied cathodic protection, metal components needed to make the metal to achieve complete protection current density for the minimum protection current density, known as the cathodic protection current density when the design, selection of the size of the cathodic protection current density is an important parameter to influence the effect of metal corrosion protective components, it has to do with the minimum protection potential (steel is a 0.85 V).

(2) During the effective protection period, the protection potential of the pipeline is not higher than 0.85V(relative to Cu/CuSO).

(A) Power supply equipment and anode ground bed:

If the selected protection current density is low, it will cause insufficient protection, metal components can not reach full protection, resulting in different degrees of erosion; On the contrary, it will cause unnecessary material and construction investment. Each composite anode contains three high silicon cast iron anodes (? 75mm×1200mm, weighing 50kg/ anodes). Considering the impressed current system allowance and the actual situation of the plant, 42 sets of potentiostat were installed according to the required protection current.