Determination of the safe operation period for oil tanks in the republic of Tajikistan. Part 2. An accelerated method for determining fire and explosion hazards

Purpose. The first part of the work demonstrated that due to a severe shortage of domestically produced oil, the Republic of Tajikistan is forced to import oil from Russia (over 85 % of the total volume), Kazakhstan, Uzbekistan, Turkmenistan, Belarus, and other countries. The fire and explosion hazard of oil, one parameter of which is the propensity of metallic structural materials of oil tanks to undergo corrosion with the formation of pyrophoric corrosion deposits, depends on the properties of the oil and its associated media – bottom water and the vapor-gas phase formed in the upper part of the tanks. These properties can vary significantly for oil extracted from different fields and imported from different countries. Objective of this work aims to select criteria for the rapid operational determination of the fire and explosion hazard of oil storage tanks. Methods. The study employed analytical chemistry methods to determine the main characteristics of bottom water (electrical conductivity, pH, salt content, presence of chloride and sulfide ions) and oil properties (viscosity, class). An electrochemical chronogalvanometry method was used to rapidly determine the relative corrosion resistance of tank steel in aqueous environments associated with oil. Findings. It was established that the corrosion deposits sampled from Russian oil production companies supplying oil to the Republic of Tajikistan contain the pyrophoric compound FeS2 and sulfur S8. A possible relationship between oil characteristics and the pyrophoric activity of the environment was determined. Chronogalvanograms of the dissolution of St3 grade steel in bottom water associated with various oil fields were constructed. Research application field. The oil and gas industry facilities of the Republic of Tajikistan. Ensuring the protection of vertical steel oil tanks from ignition. Conclusions. An express method for determining fire and explosion hazard properties of oil was developed. This method involves the parallel determination of the following characteristics: the stationary dissolution current of tank steel at a potential 30–40 mV more positive than the free corrosion potential; the viscosity class of the oil; the presence of hydrogen sulfide in the bottom water. The developed method is recommended for the rapid assessment of fire and explosion hazard properties of oil imported into the Republic of Tajikistan from foreign countries.