API RP 2003
Protection Against Ignitions Arising out of Static, Lightning, and Stray Currents
|Publication Date:||1 September 1998|
This recommended practice presents the current state of knowledge and technology in the fields of static electricity, lightning, and stray currents applicable to the prevention of hydrocarbon ignition in the petroleum industry and is based on both scientific research and practical experience. Furthermore, the principles discussed in this recommended practice are applicable to other operations where ignitable liquids and gases are handled. Their use should lead to improved safety practices and evaluations of existing installations and procedures. When the narrow limits of static electricity ignition are properly understood, fire investigators should be encouraged to search more diligently for the true ignition sources in instances where static ignition is unlikely or impossible.
This recommended practice is not required under the following conditions:
a. Static discharges may occur, but flammable vapors are always excluded by gas freeing or inerting the atmosphere in the area of discharge.
b. Product handling occurs in a closed system, and oxygen in that system is always below the minimum concentration required to support combustion, such as in the handling of liquefied petroleum gas (LPG).
c. The flammable concentration is always above the upper flammable limit (UFL).
This document does not address electrostatic hazards relating to solids handling. (See  and  in the bibliography.)