A Consideration on the Frangible Roof-to-Shell Joint of Oil Storage Tanks

Abstract

An explosion can be produced when ignition of hydrocarbon gas is caused in an oil storage tank. Such accidents happen with higher probability than other types of accidents in oil storage tanks. In relation to the explosion, the top end closure of the tank is designed to be frangible while maintaining the vaportight requirement of the welded steel structure, and is expected to fail before failure occurs in the sidewall-to-bottom joint in order to release the pressure upward and to minimize the damage. This paper presents the current design procedure according to API Standard 650 for the frangible joint, and describes the static and dynamic bifurcation buckling of the top end closure under internal pressure by using the finite element method.