BYPASS CONDUCTORS PROTECT FLOATING ROOF TANKS

Protecting your tanks from lightning strikes using a retractable grounding reel THE roof of an external floating roof tank rests directly on the surface of the stored liquid, leaving little vapour space and consequently leading to a much lower risk of rim space fire. Proper lightning protection is critical for fire prevention –the floating roof tank roof and the outer shell must be bonded continuously to prevent arcing. Fire incidents are reported in tank farms every year, and James I. Chang and Cheng-Chung Lin found that 80 of 242 tank accidents in their study was caused by lightning1. Floating roof tanks are particularly susceptible to the direct and indirect impacts of lightning. A lightning strike will cause current to flow through the shell and roof of the floating roof tank. When these lightning currents arc through the tank top, they will ignite any flammable vapours. To reduce the risk of arcing, a reliable, continuous, low-impedance and lowresistance connection between the tank shell and the roof is a must, regardless of the condition of the shell and the roof plate. There are a number of options. TRADITIONAL PRACTICE 1 Install conductive metal sheets (shunts)...