scope:

This publication presents the current technology in the fields of static electricity, lightning, and stray currents applicable to the prevention of hydrocarbon ignition in the petroleum industry. The recommendations for protection are based upon research and practical experience (see Appendixes A and B).

Purpose

Application of the information contained herein should lead to improved safety practices. This information may also be used to evaluate existing installations and procedures and, as necessary, to improve their effectiveness. Furthermore, when the narrow limits within which static electricity can cause ignition are properly understood, fire investigators may be encouraged to search more diligently for the true ignition sources in instances where ignition by static electricity is unlikely or impossible.

To prevent fires, whatever their cause, it is necessary to control one or more of the three elements required for combustion. These elements are fuel (in vapor form or mist), air, and a source of ignition. Significant sources of electrical ignition are: sparks from static electricity, lightning strokes, sparks from induced charges which may accompany lightning, and arcs caused by breaking of circuits involving stray currents. Control procedures relate to the prevention of the arc or spark itself, or to the prevention of a flammable vapor-air mixture when sparks cannot be prevented.