Abstract
Sacrificial cathodic protection system was applied for protection of prestressed concrete cylinder pipe in the Great Man made River Project pipelines in Libya, where 100 mV Polarization\Decay criteria was used to evaluate the performance of the cathodic protection.
Section of 2.29 km of protected pipeline that was existing between two sections of long non protected pipeline was selected for testing. All of the applicable tests were executed on the selected section before and after installation of sacrificial zinc anode system. The purpose of this study is to assess the reliability and efficiency of sacrificial CP system in the relatively high soil resistivity which has high chloride content and low moisture. The result of this study revealed that the 100 mV Polarization/Decay criterion was achieved in this section. The natural potential of the test section is ranged from +100 mV to -200 mV (CSE) before CP installation and the achieved instantaneous off potential was in the range of -100 to -300 mV respectively. The reliability of protected pipeline section that has achieved the 100 mV Polarization/Decay criteria is being assessed since 6 years by using of nondestructive testing inspection techniques of eddy current and acoustic monitoring to verify that this section is free of any failure resulted from embedded steel corrosion, and the result revealed that the 100 mV shift was efficient up to date.
