API RP 545 - Lightning Protection for Above Ground Storage Tanks Status Update of Ongoing Tests Per NFPA 780 (Lightning Protection Code), shunts are required to be installed on floating roof tanks above the seal at 3 meter (10 feet) feet) spacing around the tank perimeter. The purpose of these shunts shunts is to provide a conductive conductive path from the tank roof to the tank wall. Tests conducted conducted for the API RP 545, "Lightning Protection for Above Ground Storage Tanks", task group have shown that these shunts can generate showers showers of sparks during lighting lighting strikes. If there is a gap between the seal and the tank wall during a lightning strike and if a flammable mixture is present, a tank fire may result. Since the best defense against lightning is a tight seal, this reinforces the need to conduct routine seal inspections and maintenance. Also, access to tanks should be restricted when there is a potential for lightning. The API RP 545 task group is planning to conduct additional tests in order to evaluate alternative methods of providing a conductive path between the tank roof and the tank wall to meet the intent of NFPA NFPA 780. The test results and recommended mitigation measures will be included in a new RP 545 - "Lighting Protection For Above Ground Storage Tanks" (expected publication date: mid 2008). The test results with bonding conductors should be available available in early Fall 2006 and the test results results for under-l under-liqu iquid id shunts shunts should be availa available ble in early early 2007. For more information, please contact Gordon Robertson at API, 1220 L Street NW, Washington, DC, by telephone at 202-682-8190 or through email at robertsong@api.org robertsong@api.org..
