Online AE Inspection and Safety Assessment of Vertical Storage Tank

Abstract

With the rapid growth of the global petroleum industry and continuous increase of energy demand, the crude oil and product oil reserve has been given a general concern in every country, and the requirements for the reserve capacity of various types of petroleum storage depots become higher and higher, therefore, the quantity of various types of storage tanks is increasing dramatically. At present, 100,000m3 storage tank has become the primary structure for construction of crude oil storage tanks for Chinese petrochemical industry. Large vertical metal storage tank features large capacity, central distribution, storage of inflammable, explosive and toxic media etc., leakage or explosion accident, once happens, often results in disastrous consequence and severe environmental pollution, which brings a huge loss and hazard to social economy, production and people’s living. The major cause for the accidents of storage tanks is corrosion and leakage, the external corrosion is mainly the soil corrosion and moist atmospheric corrosion of outer wall of oil tank baseplate; the internal corrosion is the corrosion of tank bottom, tank wall and tank top. Among the above corrosions, the most hard to treat is the corrosion of tank baseplate. In this paper through laboratory simulation of AE tests of leakage of storage tank and corrosion of baseplate and comparison between online AE inspection of more than 30 large vertical storage tanks and shutdown inspection of part of storage tanks, the matters about online AE inspection techniques for corrosion and leakage of storage tank baseplate and safety assessment of vertical storage tank are discussed, online AE inspection technique and assessment standard fit for China’s present condition are proposed, the safety class and corresponding shutdown inspection cycle of vertical storage tank are determined, the storage tanks where no problems are found by online AE inspection continue their service, whereas the storage tanks where severe problems are found are shut down for inspection, thus the contradiction between shutdown inspection and safe production is basically solved.