Transportation of Multiple Grades of Crude Oil on Tankers: Understanding the Risk of Tank Overflow

Abstract

The possibility of oil spill from a crude oil tanker without any human intervention is analyzed. The spill can occur due to the communication of tanks containing dissimilar grades of crude oil. It will be shown that the difference in the densities of two or more grades of crude oil is possible to cause the over-fill of a tank and can raise the level to a significant height, finally leading to over flow through a purging device fitted on the top of the tank. The case is analyzed also in terms of the time needed for such over-fill to occur by studying the fluid dynamics of the self-initiated flow between tanks. Measures to prevent possible flow between tanks are presented as well as measures to avoid the spill once the flow is initiated.