FEA Buckling Analysis on an Elevated Temperature Vessel under a Vacuum

We performed (FEA) buckling analysis on an elevated temperature stainless steel vessel subjected to a vacuum loading. The vessel, constructed of 304H stainless steel, is subjected primarily to vacuum loading at elevated temperatures for the making of styrene.

Vessel dimensions are 5650 mm (222.4 inch) inside diameter and an overall height of 29.7 meters (approximately 97.5 feet). The vessel was to conform to out-of-roundness limits to both client specs and the ASME Code.

A design temperature of 1150 F was applied for the 1 inch thick shell region of the vessel. The elastic modulus for the 304H SS material of construction at this temperature is 21.3 x 10^6 psi. Instantaneous buckling during short duration temperature excursion is 1250 F. The elastic modulus in this case is 20.5 x 10^6 psi.

Both instantaneous (linear and non-linear) buckling and long term creep buckling were investigated. The analysis was performed using ANSYS finite element software, using linear shell elements (Shell 181) with creep capability.

Creep buckling analysis was completed using incremental analyses in conjunction with isochronous stress-strain data. Time-based creep analyses were also performed. The vessel was also evaluated for buckling using the method described in ASME Code Case N-284-1.

Nonlinear, instantaneous buckling analyses were completed based on the hot tensile stress-strain curve for 304H SS at 1200°F. The analysis was performed for three different loading conditions: vacuum load only, and vacuum load with 2 nozzle load cases. Results of analyses conducted using the Eigenbuckled mode shapes had 1% and 2% out-of-roundness for the initial vessel geometry.

We Perform Design and (Elevated Temperature, Thermal/ Transient, Vibration & Buckling) Analysis to ASME and other Engineering Codes.