PRECIPITATION AND KINETICS OF FERROUS CARBONATE IN SIMULATED BRINE SOLUTION AND ITS IMPACT ON CO2 CORROSION OF STEEL

The aim of present study was to study the stability of iron carbonate films formed on the surface of low alloy carbon steel used in pipeline applications in brine solution. All the tests were carried out in a stirred autoclave at various temperatures and low partial pressure of CO2. Usually, American Petroleum Institute (API) specification steels are used for carrying the crude oil and gas from the offshore to refining platforms and ultimately to the customers through pipeline routes. Developed and modified alloy steel of API grade such as API X-52, API X-56, API X-60 and L-80 are used in this study that are rapidly using in petroleum industries to transport the oil and gas. The first three grade of steel are used for transportation while L-80 grade is used for tubing and drilling the wells for recovery of oil and gas from offshore. The comparative study of their susceptibility of corrosion in severe corrosive condition has been made by measuring the corrosion rate of steel using weight loss method in simulated 3.5% NaCl test solution. The fluid velocity of simulated brine solution was maintained at a rate of 1.5 m/s for each test. The exposed samples were characterized by using Scanning Electron Microscope and X-ray diffraction techniques.