Variable conditions effect on polarization parameters of impressed current cathodic protection of low carbon steel pipes

Abstract EN

Catholic protection is an effective electrochemical technique for preventing corrosion of metallic structures.

It has widespread applications on various structures, suffering serious problems of corrosion in the environments.

The main problem with this protection method is to determine the parameters (current density and potential).

The previous works in this area used classical statistical methods to determine these parameters.

In order to determine the catholic protection potential, it is important to deal with the electrochemical studies of open circuit potential (OCP) and polarization investigations of low carbon steel used in pipeline application in 3.5 % NaCl solution at temperature range( 30- 50°C).

These studies define the corrosion potential and also help one to understand the corrosion behavior of the used metal (low carbon steel).

This system was used to investigate the influence of various conditions on the minimum catholic protection current that would provide a full catholic protection for steel tube immersed in sea water.

The variable conditions studied are concentration of (0.01–3.5) % NaCl, temperature (30- 50°C), distance between pipe (cathode) and graphite electrode (anode) of (10–20) cm and pH solution of (5.0–9.0) using a selected range of these conditions, the experimental results for the minimum catholic protection current were obtained and recorded.

The electrochemical results show that catholic protection current density increases with increasing temperature and concentration.

The current density also slightly increases with increase distance between cathode and anode.

The effective sequence of these parameters on catholic current density is as follows : Temperature > concentration > pH solution > cathode–anode distance.