Study On The Corrosion Characteristics Of The Bottom Plate Under The Condition Of Uneven Settlement Of Vertical Storage Tank

With the rapid development of petroleum and petrochemical industry,large steel storage tanks are widely used in petroleum and petrochemical industry,because of their excellent characteristics such as thin wall,high pressure resistance and good tightness.As large storage tanks are mostly built on soft land along the coast,the instability of foundation is likely to cause different settlement of tanks.The uneven settlement of tank will affect the normal operation of the storage tank.If it is serious,it will cause serious hidden danger to the tank safety.In the process of uneven settlement,the corresponding stress concentration and radial displacement will occur in the tank floor and the tank wall plate.This will cause the distortion of the tank floor and the phenomenon of the inner concave or outer convex of the tank panel,and will cause the tear in the weld of the tank floor and the tank wall plate.After the uneven settlement of tanks,the corrosion of tank bottom plates will be accelerated.Therefore,strengthening the detection of the uneven settlement of tanks and the corrosion of tank bottom plates play a very important role in maintaining the safe operation of tanks.In this paper,the mechanism of uneven settlement and the influence of different liquid level and different settlement area on the uneven settlement of the tank are analyzed by the finite element simulation analysis,the simulated settlement experiment and the test of the corrosion rate by acoustic emission.The change rule of stress change and corrosion rate change,and the change rule of AE parameters and corrosion rate are explored.The stress and radial displacement of storage tank bottom plate and tank wallboard under uneven settlement are analyzed by numerical simulation.In order to further verify the influence of different liquid level and different settlement area on the change of stress and radial displacement of tank floor and tank wallboard under different liquid level and different settlement area,the experimental system of uneven settlement of simulated storage tank is built.The experimental system of stress change and corrosion rate was set up to study the change of stress and corrosion rate with the increase of uneven settlement displacement at different concentration of corrosion medium.At the same time,the change law of corrosion rate with uneven settlement is further obtained.A system of acoustic emission detection and corrosion rate experiment was built to study the variation of acoustic emission parameters with corrosion rate and uneven settlement displacement under different corrosion medium concentration.