API RP 545-2009 pdf free download
API RP 545-2009 pdf free download.Recommended Practice for Lightning Protection of Aboveground Storage Tanks for Flammable or Combustible Liquids.1 Scope API RP 545, First Edition, Recommended Practice for Lightning Protection of Aboveground Storage Tanks for Flammable or Combustible Liquids, replaces the requirements of API 2003 regarding lightning protection for preventing fires in storage tanks with flammable or combustible contents. This recommended practice (RP) provides guidance and information to assist owners/operators with lightning protection for tanks. This RP does not provide complete protection for all possible lightning stroke occurrences. 1.1 Applicability This RP is applicable to tanks as described in API 650. 1.2 Application of Requirements to New and Existing Tanks The requirements of this RP shall apply to new or reconstructed tanks. The requirements may be applied to existing tanks at the discretion of the owner/operator. 2 Normative References The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. API/EI Technical Report 545-A, Verification of lightning protection requirements for above ground hydrocarbon storage tanks API Standard 650, Welded Tanks for Oil Storage API Standard 653, Tank Inspection, Repair, Alteration, and Reconstruction API Standard 2003, Protection Against Ignitions Arising Out of Static, Lightning, and Stray Currents ASTM D3453 1 , Standard Specification for Flexible Cellular Materials BS EN 14015 2 , Specification for the design and manufacture of site built, vertical, cylindrical, flat-bottomed, above ground, welded, steel tanks for the storage of liquids at ambient temperature and above EMMUA 159 3 , Users’ Guide to the Inspection, Maintenance and Repair of Aboveground Vertical Cylindrical Steel Storage Tanks NFPA 780 4 , Standard for the Installation of Lightning Protection Systems SAE ARP 5412 5 , Aircraft Lightning Environment and Related Test Waveforms
3 Terms and Definitions For the purposes of this document, the following definitions apply. 3.1 action integral The joule or ohmic heating energy dissipated per unit resistance at the lightning attachment point. The action integral is measured in A 2 s (amperes-squared seconds), which is the same as JΩ –1 (joules per ohm) (Rakov and Uman, Lightning: Physics and Effects, p. 277). 3.2 bonding An electrical connection between two electrically conductive objects that is intended to significantly reduce potential differences. 3.3 bypass conductor A conductive cable that provides a direct electrical connection between the tank shell and the tank floating roof. 3.4 external floating roof tank EFRT An aboveground tank with a floating roof, which has no fixed roof and has an open top. 3.5 flash A complete discharge of the cell between the thundercloud and ground (as it applies to cloud-to-ground lightning) (Uman, The Lightning Discharge, p. 10). 3.6 grounded (grounding) Connected (connecting) to ground or to a conductive body that extends the ground connection (NFPA 780). 3.7 internal floating-roof tank IFRT An aboveground fixed roof tank with a floating roof inside the tank. 3.8 release prevention barrier A release prevention barrier includes steel bottoms, synthetic materials, clay liners, and all other barriers or combination of barriers placed in the bottom of or under an aboveground storage tank, which have the following functions: a) preventing the escape of contaminated material, and b) containing or channeling released material for leak detection.
3.9 shunt A short conductor that is electrically connected to the tank floating roof and contacts the tank shell. 3.10 striking distance The distance over which the final breakdown of the initial lightning stroke occurs. 3.11 stroke One current component of a lightning flash. The number of strokes per flash is typically three to four, but may be as low as one or as high as 30 (Uman, All About Lightning, p. 41). 4 Protection of Specific Types of Tanks 4.1 Fixed-roof Tanks (Metallic) and Tanks with Internal Floating Roofs For fixed roof tanks (metallic cone or dome) and internal floating-roof tanks (IFRTs), there is a possibility of flammable vapors being present at atmospheric vents. If present, flammable vapors can be ignited by a lightning flash. Shunts or bypass conductors are not required for lightning protection. Bonding techniques to prevent static discharge between the floating roof and shell are addressed in API 650, Appendix H. Tanks handling low vapor pressures or in-service with properly maintained floating roofs with tight-fitting seals are not likely to have flammable vapors at atmospheric vents unless it is being refilled from empty. In these cases, no further lightning protection is required (see Annex B). 4.2 External Floating Roof Tanks 4.2.1 Bonding Between Floating Roof and Shell 4.2.1.1 Shunts for Conduction 4.2.1.1.1 General Shunts are used for conduction of fast and intermediate duration components of lightning-stroke current. 4.2.1.1.2 Number and Placement The shunt to shell contact point shall be submerged at least 0.3 m (1 ft) below the surface of the liquid product. The shunt shall have as short and direct a path as possible from the conductive floating roof to the tank shell. The shunts shall be spaced at intervals no greater than 3 m (10 ft) around the perimeter of the floating roof.
