Lightning Risk Assessment of Pipeline Insulating Flanges with Isolating Spark-Gap

Insulating flanges are components that are inserted between two segments of a pipeline to ensure electrical isolation. The use of these components is a necessity for the effective operation of the cathodic protection system of buried pipeline systems. Also, an isolating spark-gap is usually installed between two pipeline segments to eliminate the stress voltage that appears on the insulating flange under the occurrence of a lightning event. However, in some cases, the voltage-drop across the connecting cables of the isolating spark gap may exceed the dielectric strength of the insulating flange, causing detrimental failures. The voltage-drop primarily depends on the parameters of the incoming surge as well as the configuration and the length of the connecting cables. In this paper, we provide simple theoretical calculations as well as complex modelling techniques that can be used in assessing the lightning risk of pipelines' insulating flanges incorporating isolating spark gaps.