Cleaning the huge oil storage tanks is very costly, hazardous, and time-consuming. However, this issue is one of the main concerns of the petroleum products storage industry that is performed in different ways. In this paper, an innovative oil storage tank cleaning procedure in which vertical cylindrical tanks are cleaned without entering any labor into the tank and damaging it is introduced. In this method, before filling the tank with petroleum products (i.e., oil), a sack of PVC fabric is located at the bottom of the tank, and as time passes, the heavier particles (sludge) settle on this sack. Finally, when the sack is filled with sludge, through a mechanism, it is, firstly, shifted towards the center of the tank and, secondly, lifted and taken out through the gate that exists on the roof of the tank. Thus, the above-mentioned approach not only reduces the cost of the cleaning operation but also accelerates the speed of the performed operation. To analyze the stress which is imposed on the sack’s fabric by the weight of the sludge, the finite element method has been applied. The highest stress undertaken by the sack was obtained as 7.630 MPa, which, according to the mechanical properties of the investigated fabric, shows an acceptable safety factor of 1.5. In addition, the strength of the tank’s walls against buckling due to the weight of the sack and sludge was investigated.