Diyala Journal of Engineering Sciences (Dec 2015)
PREDICTION THE THICKNESS LAYER OF GALVANIZED IRAQI ELECTRICAL POLES USING MATHEMATICAL MODEL
Abstract
Galvanized steel has a long history as an effective and economical material for manufacturing electrical poles. Galvanized steel consists of a thin coating of zinc fused to a steel substrate. This combination provides the pole high mechanical properties as the mechanical properties of steel enhanced with the corrosion resistance of zinc. Corrosion rates have been calculated by Tafel extrapolation technique for different coating thicknesses (80, 90,100,110,120 and 130) μm. The soil resistivity is simulated by different concentrations (2, 2.5, 3, & 3.5) wt. % NaCl. Optical microscope examinations for their specimens were used successfully to evaluate corrosion rates for the galvanized steel poles. Regression model has been used in this work to find the correlation between the corrosion parameters representing by thickness of galvanized layer of low carbon steel and resistivity of soil. Matlab (R 2013A) programme was used to get the unknown cofficients of the regression model . Theoretical mathematical equations were performed to predict the thickness layer of galvanized Iraqi electrical poles to get the best thickness of galvanized layer which has high corrosion resistance in different soil resistivity. This is considered the aim of this work. The results of the mathematical model show that the corrosion rate of galvanized steel decreases with the increase in coating thickness from 80 - 120 μm. The best corrosion resistance occurs at thickness 120 μm galvanized layer, while at 130 μm thickness micro cracks appear in the coating layer. The coating thickness has a direct influence on the performance or life of the electrical poles. As the thickness of galvanized layer increases, the life of protection increases until 120 μm.
