Impact of Environmental Conditions on Sub-Surface Storage Tanks (Part I)

The present investigation concentrates on the effects of environmental changes upon sub-surface storage tanks that are frequently used in the Niger Delta region and other parts of Nigeria for Petroleum Products. The research is part one of a long-term study that aims at the determination of corrosion rates of the under ground tanks within the Port Harcourt Municipality. Cast iron made storage tanks with gasoline fluid were buried under the soil at a depth of 4 m under various environment conditions. The simulated conditions include natural rain fail, temperature and acidic, alkaline and neutral soils. A control condition of neutral sea sand as base and filling materials were also investigated. After various exposure periods, the densities of the storage tanks, composition of soil, soil pH, corrosion rates and soil resistivities were determined. The experiments were repeated after every six months. Within the last three years, it has been observed that the corrosion rates of the tanks covered with cellophane materials were relatively less than those tanks that were buried directly with in the soil except that of the control experiment. In addition the corrosion rates of tanks buried within the acidic environment were more than those buried within the alkaline and neutral soil conditions. Also, it was interestingly observed that the corrosion rates were generally and initially very rapid during the first year of the work, but with time it decreased. Equally the water content of the soil was low. The soil resistivity increased relatively to the control sample site. @JASEM