This study addresses the problem of stability (standing of cylinders upright) of DOT-39 nonrefillable refrigerant cylinders using both experimental and finite element analysis (FEA) approaches. When these cylinders are designed using traditional methods they often suffer permanent volume expansion at the bottom end closure and become unstable when they are pressure tested experimentally. In this study, experimental investigations were carried out using hydrostatic pressure tests with water. In the case of numerical investigations, FEA models were developed for three-dimensional (3D) axisymmetric quasi-static conditions. The FEA models were constructed using nonhomogenous material nonlinearity and geometrical nonuniformity conditions. The results obtained from both FEA models and experimental tests were compared. To eliminate the instability of these cylinders, a design of experiment technique was employed to optimize the bottom end-closure design using the FEA models.