Author : A. Ali, Ghalib
Variable Conditions Effect On Polarization Parameters Of Impressed Current Cathodic Protection Of Low Carbon Steel Pipes
Engineering and Technology Journal,
2008, Volume 26, Issue 6, Pages 636-647
Cathodic 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 cathodic 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
cathodic protection current that would provide a full cathodic 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 cathodic protection current
were obtained and recorded.
The electrochemical results show that cathodic 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 cathodic current density is as follows:
Temperature > concentration > pH solution > cathode – anode distance .