Effect of sloshing on a local structural system in a partially filled tank

Abstract

A ship structure, as an elastic body, will vibrate when exposed to external loading. A tanker carrying liquid cargo will experience vibrations in the tank structure caused by liquid sloshing. Local structural systems located within the tank are particularly susceptible to sloshing. In this paper, a local cargo pump pipe stack structural system located inside a generic tank of a production tanker is investigated for possible fatigue cracking caused by sloshing-induced vibration. Several different filling levels are analysed using computational fluid dynamics (CFD) simulation, and the stress response is found by finite element analysis (FEA). A reliability model is developed to estimate the possible occurrence of fatigue crack growth at the supporting components attaching the pipe stack to the tank wall. Different estimates for the initial size of a crack assumed to be present in the welded pipe stack support are evaluated. It is found, under the given circumstances, that it is likely that an initial crack will start to grow.