Galvanic Cathodic Protection Evaluation of a Steel Pipe in Iraqi Soil

Abstract

Corrosion is the main problem for the embedded pipelines in differentenvironment resistivities. The most effective method to overcome this problem iscathodic protection which represents as a control method of the pipe corrosion.For achieving longer life of the external corrosion control system and evaluatingthe performance of aluminum alloys which have been used as sacrificed anodesto protect the embedded carbon steel pipe in different artificial simulatedresistivity of soils in Iraq of [5000 , 1000 , 600 , 50 and 25 (Ω.cm)]. Results showthat (Al-10 wt% Zn) as sacrificial anode alloy has the best anode capacitycompared with other anodes under these conditions (Al-5 wt% Zn), and (Al-15wt% Zn). The selection for these alloys based on that they have high potential inmany environments when coupling with steels without effect of microbial,obstacle and stray current. The polarization curves of alloys also show nopassivation behavior in artificial resistivities. The corrosion rate of different anodealloys was determinated as a function of applied cathodic protection.It was found a relationship between electric potential and time whichdetermine the optimum potential in different soil types for the three above selectedelectrodes (anodes).