Evaluation of Effect of Angular Positioning of Legs on the Structural Stability of a Pressure Vessel Using Finite Element Analysis

Abstract

Pressure Vessel design is primarily a process that is guided by the time tested principles of ASME code. The code has incorporated experience of past 100 years to create a rule based design approach.  However this approach is applicable to only standard designs, and it is not feasible for ASME to give rules for nonstandard designs, hence ASME itself has recommended a design by analysis approach for such designs. Process requirements for the vessel under consideration of this paper, dictated that there should be an unsymmetrical distribution of leg supports. The vessel has six legs, with two of them having a gap of 80 degrees and the remaining maintaining a gap of 56 degrees. This variation from a normal 60 degree standard separation makes it a nonstandard design fit for design by analysis approach. In addition to this the supports are also titled with respected to the vertical. This angular inclination in combination with the unsymmetrical distribution of legs is the focus of this paper, wherein the effort is to evaluate the effect of this on the structural parameters of deformation and stress.