The Remaining Life Prediction and Internal Inspection Interval Analysis for Large-Scale Crude Oil Storage Tank

As an important production facility, storage tank plays a more and more important role in the storage and transportation of crude oil and chemical product. The remaining life prediction of storage tank is to forecast the thinning trend of plate thickness, and forecast remaining life on the premise that remaining strength of storage tank meets the tank operation and safety requirements. Maximum corrosion depths of tank bottom plate obey the maximum extreme value distribution. Based on maximum extreme value distribution and statistics of corrosion data, the calculation formula of the remaining life prediction for large-scale crude oil storage tank was obtained by formula derivation. Compared with API STD 653 and EEMUA 159, the inspection interval specified by China standard SY/T 5921 is relatively conservative. The remaining life of a certain crude oil storage tank (tank A) in china is determined by the remaining life of tank bottom plate. The remaining life of tank A at the reliability of 0.99, 0.999 and 0.9999 are 25 years, 20 years and 17 years, respectively. For the acceptable failure probability of 1×10⁻⁴, the inspection interval of tank A can be extended from required 5–7 years specified by China standard SY/T 5921 to 17 years. The remaining life of crude oil storage tank predicted by the method proposed in this paper can be used as an important reference in the determination of inspection interval and tank’s maintenance.