Lightning strikes are far more common than many realise and, with the changes in the global climate and changing weather patterns, they are well and truly on the increase. Australia is at particular risk because, according to a joint NASA and National Space Development Agency of Japan study, approximately 70 percent of lightning occurs on land in the tropics, where the majority of thunderstorms occur.
Two of Australia’s most prominent resources companies, Coogee Chemicals, which manufactures a range of chemicals at its plant in Kwinana Beach, north of Rockingham, and oil and gas exploration and production company, Apache Energy, which has processing facilities on Varanus Island, approached Delta Fire as they need to boost fire protection at their Western Australian facilities. Their floating roof storage tanks required protection against being ignited by a direct or nearby lightning strike. About a third of all tank fires are believed to have been started by a lightning strike which makes a lightning protection system a necessity.
Delta Fire supplied both Coogee Chemicals and Apache Energy with RGA (Retractable Grounding Assembly) grounding/earthing equipment for lightning protection.
The RGA equipment is designed and manufactured in the USA for the protection of above-ground storage tanks containing flammable or combustible liquids and has proven its reliability and effectiveness with more than 3,000 successfully operating installations around the world. It is a retractable conductor wound onto a spring-loaded reel – which is mounted directly on the tank wall or a suitably positioned mounting bracket – that is designed to electrically bond the floating roof and shell on floating roof storage tanks.
The RGA equipment provides the lowest impedance connection between the roof and the shell of a floating roof tank, particularly when the roof is high, by creating the shortest possible path between the two. This connection is maintained by keeping constant tension on the wide tinned-copper-braided cable so it is, unlike conventional fixed-length bypass conductors, always as short as possible regardless of the position of the floating roof.
For both the Coogee Chemicals and the Apache Energy projects, the equipment was installed by the resources companies’ own personnel. Coogee Chemicals protection called for two RGA-75 systems, while the Apache Energy project required seven.
The RGA solution can be installed in both new-build or retro-fitted to existing tanks and requires little regular testing, inspection or maintenance other than visual inspection of all moving parts, the removal of dirt and debris, lubrication of the bearings, and the tightening of all mechanical fixings. The ATEX certified equipment is CE Ex II 2 G T4 certified, signifying the RGA’s compliance with the requirements of Directive 94/9/EC involving potentially explosive atmospheres.