Analysis and experimental investigation of direct lightning protection for floating roof oil tanks

To improve the lightning protection of large floating roof oil tank, the process of floating roof tanks stroked by lightning is analyzed, and relevant tests have been developed according to the standards. Test results indicate that the major role of conductive film is to release lightning current rapidly, but the presence of conductive films has their counter-effect. As long as conductive film exists, it will generate electric sparks when the floating roof tanks stroked by lightning. So the paper was proposed to abolish the conductive film on the second seal floating roof top edge and adopt scalable grounding device(SGD) as lightning protection measures. Empirical formula has been used to calculate the transient voltage drop when the 100000 m3 tank was stroked by lightning. The results show that the floating tank is safe when there are 20 SGDs uniformly connected with floating roof and tank wall.