In the last the last ten years mounded cylindric pressure vessels for the Foundation methods storage of explosive and other dangerous liquids have gained an increasing significance with regard to growing safety requirements. These tanks are usually placed in a sandbed and covered with earth. The interactions between operational loadings and soil pressure on the one side, and reactions from elastic foundation on the other side, necessitate an accurate investigation. The nonaxisymmetric loadings create circumferential bending reactions and ring stiffeners have to be installed. With internal pressure, these stiffeners hamper the expansion of the cylindrical shell and cause secondary bending in the longitudinal direction of the vessel. This paper gives a survey of common construction methods and describes the major calculation procedures required for the design.
For the storage of combustible liquids under atmospheric pressure and liquefied gases under high pressure, the horizontal cylindrical steel vessel with earth cover has been increasingly applied within the last years. The decision for the earth covered type of installation is mainly justified by the safety advantages in respect to external influences on the vessel, such as high temperature in case of fire and dynamic pressure from near by explosion. The vessels are placed in trenches or above ground and covered with earth. The type of installation as well as storage conditions, structural dimensions and assembly methods have to be considered within the design of the cylindrical steel vessel. As a rule, only single horizontal vessels with capacities up to 400 m3 and diameters up to 4.0 m are placed in trenches, whereas within an aerial installation under embankment, several vessels are preferably installed in a battery line-up. With this type of installation, vessels with contents up to 4000 m3, diameters up to 8.5 and lengths up to 100 m are designed at present.
