Analysis of Effective Parameters in Design of CNG Pressure Vessels

The mass production of natural gas pressure vessels is needed to be carefully examined concerning formation stages and the effective parameters on the production stages of the vessels. Since pressure vessels should be produced seamlessly, the conventional method for building vessels metal core include the use of an initial blank and performing deep drawing formation, redrawing, ironing and finally rotational forming for vessels dome and throat. In this paper a review of the history of production and the manufacturing method is presented. Then, finite element method is used for simulation of initial stages of forming the CNG vessel core. The simulation of production process consists of the cold deep drawing, cold redrawing and finally two steps of ironing the vessel walls (without considering hot spinning in order to close the vessel dome). A stage of stress releasing is performed at the end of each stage of forming. The required force for forming and also the change occurred in the blank thickness is examined in this study. The results of simulation done by other researchers were compared with the finding of this study. The comparison showed a good level of agreement between the obtained results. These results help the designers to design better.