الحماية من التاكل لقواعد الاعمدة الكهربائية في الترب ذات المقاومية المنخفضة == Corrosion Protection of Electrical Bar Stands In Low Resistivity Soil
Author name:
اياد نصيف جاسم
Supervisor name:
سامي ابراهيم جعفر الربيعي
General topic:
Production engineering metallurgy and materials
Specific topic:
Metals Engineering
Degree:
Master
University:
University of Technology
Language:
English
University location:
Baghdad
First pages:
50T179 - p.pdf
Abstract:
يستخدم الفولاذ المغلون في تصنيع الاعمدة الكهربائية لامتلاكه خواص ميكانيكية جيدة ومقاومة تاكل عالية. وتحت الظروف الاعتيادية يعاني العمود من التاكل بعد عدة سنوات من الخدمة.يصنع عمود الكهرباء من فولاذ St - 52 والمطابق للمواصفة DIN الالمانية ويتالف من ثلاثة | Galvanized steel is used in electrical poles because of the good combination of its mechanical properties and the corrosion resistance. Under normal conditions, electrical pole suffered from corrosion after some years in service. Electrical poles, which were made according to Germany standard DIN st.52, consist of three parts; the upper, mid and lower part. This study focuses on the last part because the surrounding soil of electrical pole is more corrosive than the atmospheric environment, which surrounds to other two parts of the electrical pole. Soil resistivity is the one variable that has the greatest influence on corrosion rate. Electrical poles which at buried in low resistivity soils will generally be anode, whereas electrical poles buried in adjacent high resistivity soils will generally low corrosion.The electrolyte in this work was prepared according to the values of Iraqi soil resistivity. Sodium chloride (NaCl) was used in different concentrations of (2, 2.5, 3 and 3.5) wt. %, which are equivalent to 27, 24, 20 and 18 ohm.cm. Two methods were used in this work in order to improve corrosion resistance, the first method galvanizing process in different thicknesses (80, 90,100,110,120 and130) µm and the second method is coating by different types of Iraqi paints (D - 5547) with hardener (H - 1457)and(G - 5532,G - 5533,D - 5542) with hardener(H - 5533) The corrosion rate and corrosion potential of steel increases and decreases with the increase in NaCl wt.% concentration respectively. Corrosion rates (mpy) with coating thickness are achieved as a function of environment in different soil resistivities. The more corrosion resistance occurs at 120 µm galvanized layer. Micro cracks appear at 130 µm galvanized thickness.In this work, two mixed ratios of paint and hardener were used. These ratios are 2 : 1 and 1 : 1. Paint with mixing ratio equal to 2 : 1 of G - 5532 + G 5533and mixing ratio 1 : 1 D 5542 with hardener 5530 gave the more corrosion resistance.The coating thickness has a direct influence on the performance or life of the electrical pole. As the thickness of galvanized layer increases, the life of protection increases until 120 µm. The life of a zinc coating is a linear function of coating weight for any specific environment. The efficiency of coated electrical pole either by galvanization or paint process was a proximately between 94% to 97% and 98% to 99.6% respectively.
