Lightning exposure of oil tanks with changing roof position

Abstract

Crude oil and related petroleum products are major fossil fuels for the supply of energy globally. Floating Roof Tanks (FRTs) are used for storing crude oil after production to ensure product stability before product export, but FRTs are susceptible to lightning strikes. Lightning is a major threat to operational safety in crude oil storage terminals, particular in the tropics with a very high number of thunderstorm days per year (Td/yr). Protecting crude oil storage tanks against the high-energy lightning current with a continuing current charge of 200 Coulomb requires the design and implementation of a purpose-specific lightning protection system. An evaluation of the probability of a lightning strike to a FRT using the dynamic electro-geometrical model (DEGM) was performed using numerical techniques. The results for the cases considered show that the total probability of a direct strike to the circular tip of the tank shell at its topmost height varies from about 85% to 99% depending on the dimension of the tank and the position of the floating roof within the tank.