Peak Stress and Fatigue Assessment at the Saddle Support of a Cylindrical Vessel

Abstract

The maximum stress in a saddle-supported cylindrical storage vessel is often the circumferential stress developed at the tips (or horns) of the saddle support. Although the peak stress at the support is not immediately detrimental to the integrity of a vessel, it would have a long-term effect on the fatigue life of the vessel. This article provides a parametric equation to determine the peak circumferential stress at the support. To assist calculations, a worksheet procedure has been proposed. The parametric equation is accompanied by four graphs, each graph provides values for a geometric variation of the problem. An example has been shown on the application of the parametric equation. A fatigue assessment is also made on the example vessel and comparison is made between ASME and British design codes. The parametric curves can be also used as a set of design curves for specifying support dimensions.