EPCC of Cathodic Protection System

Engineering, Procurement, Construction & Commissioning of a CP System, what are the considerations?

Design consideration?
-the structures to be protected, material type etc?
-the electrolyte the structures are immersed in?
-the coating type

Will all these be sufficient in order to have a good CP system? let me leave it at this as I need to hear some opnions before I start dishing out what I have experience.....

Cathodic Protection System

Cathodic Protection is a technique to prevent corrosion of underground structures, sush as buried pipelines, tanks in contact with an electrolyte.

Cathodic Protection is an electrochemical means of corrosion control in which the oxidation reaction in a galvanic cell is concentrated at the anode and suppresses corrosion of the cathode in the same cell. The image below shows a simple cathodic protection system.

The structure to be protected is purposely made a Cathode of an electrochemical cell with respect to an Anode, a less costly & expendable material, which gets consumed & can be replenished as required.

Corrosion Mechanism

* Corrosion in an electrochemical reaction
* An Electrochemical cell contains four main components:
1. Electrolyte
2. Anode
3. Cathode
4. External Circuit

ELECTROCHEMICAL CELL
Fe ---->Fe++ + 2e- (1)
O2 + 2H2O + 4e- ----> 4OH- (2)
2H2O + 2e- ----> H2 + 2OH- (3)

what is corrosion??

The deterioration or degradation of materials, usually metals because of the environment

& why do metal corrode?

* Most metal used in construction are subject to corrosion.

* This is due to high energy content of the elements in metallic form.

* In nature, most metals are found in chemical combination with other elements.

* Which later change into metals or alloys by introduction of energy.