Variable Conditions Effect On Polarization Parameters Of Impressed Current Cathodic Protection Of Low Carbon Steel Pipes


Cathodic protection is an effective electrochemical technique for preventingcorrosion 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 statisticalmethods to determine these parameters.In order to determine the cathodic protection potential, it is important to deal withthe electrochemical studies of open circuit potential (OCP) and polarizationinvestigations of low carbon steel used in pipeline application in 3.5 % NaCl solution attemperature range( 30- 50°C).These studies define the corrosion potential and also helpone to understand the corrosion behavior of the used metal (low carbon steel ). Thissystem was used to investigate the influence of various conditions on the minimumcathodic protection current that would provide a full cathodic protection for steel tubeimmersed in sea water. The variable conditions studied are concentration of (0.01 – 3.5)% NaCl , temperature (30- 50°C), distance between pipe (cathode) and graphiteelectrode ( anode ) of (10 – 20) cm and pH solution of (5.0 – 9.0) using a selected rangeof these conditions, the experimental results for the minimum cathodic protection currentwere obtained and recorded.The electrochemical results show that cathodic protection current density increaseswith increasing temperature and concentration. The current density also slightlyincreases 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 .