American Petroleum Institute

Protection Against Ignitions Arising out of Static, Lightning, and Stray Currents - EIGHTH EDITION
 N RP 2003

Annotation

General

This recommended practice (RP) 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 RP 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.

Following this recommended practice is not required where:

a) static discharges may occur, but flammable vapors are verified to be 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 verified to be below the minimum concentration required to support combustion, such as in the handling of liquefied petroleum gas (LPG);

c) the flammable concentration is verified to be above the upper flammable limit (UFL).

This document does not address electrostatic hazards relating to solids handling. (See [4], [5], and [15] in the Bibliography.) Vehicle fueling (truck or passenger car) is also outside the scope of this document.