For most people, static electricity is simply a nuisance. It makes our clothes stick to us, and can give us a bit of a jolt when we reach for the metal filing cabinet.
Static electricity is the electric charge generated when there is friction between two things made of different materials or substances. Electric charges can build up on an object or liquid when certain liquids (e.g., petroleum solvents, fuels) move in contact with other materials. This can occur when liquids are poured, pumped, filtered, agitated, stirred or flow through pipes. This buildup of electrical charge is called static electricity. Even when liquids are transported or handled in non-conductive containers, something rubbing the outside surface of the container may cause a static charge to build up in the liquid. The amount of charge that develops depends, in part, on how much liquid is involved and how fast is it flowing or is being agitated or stirred.
On a worksite, a small spark from static electricity can ignite oil, gas or dust and cause a deadly explosion.
- Static electricity possibly behind Colorado oil and gas well explosion
- Series of explosions at a Sunrise Propane facility in Toronto
- The Hindenburg Disaster
The Canadian Occupational Safety article “Little spark, big flame“, the following equipment and operations pose a greater risk:
- Fuel and storage tanks: Those made of steel or fibreglass can develop a static charge between the liquid surface and the tank shell or metallic fitting in a non-metallic tank during filling.
- Propane gas cylinder processing facilities: The propane present in the air can be ignited by static electricity.
- Frack tanks: Static charges can build up and ignite residual oil and trapped gases in the tank. Static electricity can be generated when dissimilar molecules such as water, oil and sediment in the flowback fluid collide and form positive and negative charges.
- Fuelling operations: The flowing movement of flammable liquids like gasoline inside a pipe can build up static electricity. Liquids such as paraffin, gasoline, toluene, xylene, diesel, kerosene and light crude oils exhibit significant ability for charge accumulation and charge retention during high velocity flow.
- Natural gas pipelines: Friction caused by dust or constrictions in the pipe can cause static buildup on pipes used to transport natural gas. If there is a negative charge inside the pipe, it will attract an opposite equal charge through the soil and to the outside of the pipe. When the pipe is uncovered, the charge outside the pipe can arc.
How do you prevent an accident?
Workers should receive proper training on the grounding and bonding and wear the right protective equipment for the job.
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