Wall Fusion of Buried Pipelines Due to Direct Lightning Strikes: Field, Laboratory, and Simulation Investigation of the Damaging Mechanism

Abstract

Wall fusion of buried pipelines can occur if the driving voltage and available current is sufficiently high. For example, it can occur from direct lightning strikes to earth, close to the pipelines' routing. However, not all factors for defining the energy discharge needed to fuse the pipe wall are thoroughly investigated or understood. This paper enriches the ongoing research activities in an attempt to understand such detrimental damages. In particular, the paper formulates its research contents around a documented wall fusion incident on an underground gas transmission system, due to a nearby direct lightning strike. The investigation embraces field, laboratory, and modeling activities to provide insights on the damaging mechanism. Of particular importance in understanding this mechanism is the influence of soil ionization. To this end, a model is developed to investigate the soil-ionized flow of the lightning discharge current-into the pipeline's metal wall, through existing coating defects-thus revealing its detrimental effect.