The Undesirable Interaction of Lightning Strike and Floating Roof Tanks

Abstract

A lightning strike to a floating roof tank (FRT) can induce fire, and if the fire is not properly managed, a full surface fire and a complete tank boil over may ensue. The optimal approach is to prevent lightning-induced sparks rather than firefighting. Designing a lightning protection system (LPS) for a FRT is quite intricate due to its large tank dimensions and the movable roof. This study explores the probability of a direct lightning strike to a floating roof tank using the dynamic electro-geometrical model. The impact of various tank dimensions on strike probability was investigated, and the result shows that the probability of a strike to the rim edge of the FRT reduces with tank diameter and increases with tank height. Various LPS air termination arrangements are proposed to be deployed on and around a FRT to channel the lightning current and associated energy via multiple flow paths. Challenges that may hinder implementation are also identified.