The behaviour of a horizontal vessel on loose saddles — a buckling assessment of the support region

By using two computer-based buckling programs, NASTRAN and BOSOR4, the buckling behaviour of the support region of six horizontal storage vessels is assessed. The vessels are supported on twin saddles shown in Fig. 1(a) and of diameter/thickness ratios from 312 to 1154, and lengih radius ratios from 4 to 6.5. They were chosen to provide a range of typical vessels in present use. The specific gravity of the liquid contents required to cause buckling in the support region was obtained by using the computer programs and also by using an equivalent cylinder length with the existing formulations given in the British Pressure Vessel Code, BS 5500 for axisymmetric loading. Comparison of these approaches is used to validate a procedure for finding an allowable buckling stress, hitherto not available for this component.