(0c) Electrostatic Hazards: Early Warning Signs

Electrostatic sparks are known to cause many industrial fires and explosions each year. Yet it is not unusual to find that before an incident, operators or supervisors have encountered signs that static electricity is present. These signs can be as apparently innocuous as dust patterns on plastic or a prickling feeling on the arms. They can also include unexpected corrosion in a glass-lined vessel or even a pin-hole leak from an insulating pipe. And these in addition to the well-recognized sparks and cracking sounds that present themselves as the more obvious face of static electricity.

Identification of electrostatic phenomena - early warning signs - on plant can never be a substitute for the detailed hazard assessment work that focuses on the identification and elimination of all potential ignition sources. But electrostatic sources of ignition are often considered to be more complicated to identify and eliminate than others. Consequently, they frequently elude the formal HAZOP or hazard study process. With electrostatic hazards, this makes vigilance by operatives and others that much more important, especially since electrostatic effects can easily be spotted by the informed.

In this paper we bring together the principle manifestations of static electricity on industrial facilities and group them by class. We discuss how these manifestations should be interpreted by reference to discharge types and associated energy ranges. Finally, we discuss how we can go about assessing whether or not each static manifestation could lead to an electrostatically initiated fire or explosion as well as how they can be eliminated.