Volume II, Issue XI, November 2015 IJRSI ISSN 2321 - 2705 www.rsisinternational.org Page 57 Relationship between Soil Properties and Corrosion of Steel Pipe in Alkaline Soils Vishal M. Bansode, S.T.Vagge, Aniket B. Kolekar Metallurgy and Material Science, College of Engineering Pune Abstract-This paper investigates the relationship between soil properties and corrosion of low carbon steel pipe in three different soils. The study focuses on major soil properties such as soil resistivity, soil moisture content, soil redox potential, and chloride, sulphate, bicarbonate contents. The steel pipe specimens were dipped into 3 different soils for 7 months and after 7 months of soil exposure the relationship soil properties and corrosion rate of steel pipe plotted and analyzed. Keywords: Soil Corrosion, Soil Properties, Soil chemistry Corrosion relationship, Polarization I. INTRODUCTION orrosion is defined as degradation of material or its properties due to a reaction with environment. Soil corrosion is a complex phenomenon with number of factors involved. Soil corrosion as deterioration of metal or other material brought about by chemical, mechanical and biological action by the soil environment. [8] The corrosion of ferrous metal in soil is a major problem for distribution of water, sewage, oil and gas system. The most common corrosion failure mechanism for buried ferrous pipe is localized corrosion leading to leaking. [1] The pipeline corrosion is most prevalent when breakdown of coating, inhibitors or cathodic protection take place in corrosive environment. Author proposed the model with seven stages of corrosion life. These seven stages consist of Pit nucleation, Pit growth, transition from pitting to fatigue crack nucleation, short crack growth and transition from short crack to long crack, long crack growth and failure. [2] The common types of corrosion that can occur in a buried pipe are:-  Pitting corrosion owing to material inhomogeneities.  Chloride and sulphate induced stress corrosion cracking  Corrosion by concentration cell in soil arising out of difference in oxygen concentration in soil adjacent to the pipe at different region.  Microbiologically induced corrosion under anaerobic condition by sulphate reducing bacteria and acid forming bacteria.[2] The soil engineering properties and soil content are important parameter that influences the soil corrosivity and level of corrosion dynamics these are namely Soil resistivity, Soil pH Soil redox potential, Soil temperature, Soil content ,Liquid limit , Plastic limit, Soil chemical content etc.[8,5,15] II. EXPERIMENTAL 2.1 Materials and Methods It has been aimed to investigate corrosion performance of buried pipeline. Therefore material selected for this study is commercially used Mild Steel pipe having chemical composition as shown in table 1. Table 1 - Chemical composition of MS pipe used for corrosion study Elements C Mn Si S P Fe Wt. % 0.040 0.12 0.032 0.007 0.012 Balance 2.2 Soil collection Soil samples for the study collected from three different locations covering approximately 20 km distance. At each of selected locations the soil samples were collected by digging a hole of 0.5 m deep. Soil sample will be collected from each sites and kept in polyethylene bags before sent to the laboratory for further soil analysis. 2.3 Soil analysis The collected soil samples were tested for soil corrosivity properties such as soil resistivity, soil redox potential, soil pH, soil moisture contents in a laboratory as per IS 2720 Standard and soil chemical composition in which chloride contents (Cl - ) as per APHA 4500-Cl-B, soluble bicarbonate (HCO 3 - ) as per APHA 2320 B, Sulphate contents (SO 4 -- )as per IS 3035 (Part 24) and Nitrite contents as per IS 3035 (Part 34). The moisture content of soil sample was calculated using weight loss technique as per IS 2720 (Part 2). For this a 30 gm of each soil sample is dried in a drying oven at 110 0 C for 24 hrs. The weight difference between sample before and after evaporation is regarded as the moisture content. [2] C