Talking the hazards of static electricity in chemical industry is like re-open my memory when I was facing such kind of incident in the plant several years ago.
The accident happened when metallic-powder catalyst charging was being done from a wagon into catalyst feeder with poor earth grounding and incomplete flammable gas substitution.
Static electric sparks were created and ignited flammable gas inside the catalyst feeder immediately. A fire occurred.
That is only an example of static electricity fire hazards.
Static electricity can cause a fire and may an explosion. The effect will be very huge.
So, that’s why I think it is very important to share about this topic with all of you.
Let’s get started.
Accidents Caused by Static Electricity
Most of these accidents involve static electricity fire hazards. It means that they involved flammable vapors or gases.
Please look at the statistics below:
According to Yuqin Hu , there are 99 accidents that occurred in the process of oil-gas storage and transportation in the last 30 years caused by static electricity. 85% of those accidents occurred in tank farms, gas station, and petroleum refineries.
In Japan, from 1960-2010 (50 years), 153 accidents, which caused by static electricity, had occurred in petroleum and chemical industries .
On October 29, 2007, a fire and series of explosion at Barton Solvent, Iowa, US occurred due to static electricity. Based on Chemical Safety Board investigation result, this accident was caused by poor electrical bonding and grounding during the filling process of hydrocarbon.
All the above accidents had left a clear message about hazards of static electricity: appropriate static electricity control is so important.
What is Static Electricity?
Before we dive into the static electricity hazards, it had better understand the definition of static electricity.
What is static electricity actually?
First, from a general dictionary. Static electricity a stationary electric charge, typically produced by friction, that causes sparks or crackling or the attraction of dust or hair.
Wikipedia has a slightly different definition. It defines static electricity as an imbalance of electric charges within or on the surface of a material, which remains exist until it can move away in the form of electric current or electric discharge.
A simpler definition was written by Dirk Smith: the friction of one insulator against another displaces electrons, which accumulate on one of the surfaces.
The friction (i.e the forces) of two materials is the main cause of static electricity generation. We shall take care of it.
There are many kinds of operations in a chemical manufacturing plant that create static electricity such as feeding, flowing, pouring, agitating, filtering, mixing, vacuuming and pumping.
Meanwhile, the charging rate of static electricity depends on several factors, i.e flow rate, turbulence level, poor material conductivity and contacting surface area.
Hazards of Static Electricity in Chemical Industry
Static electricity can release sparks if it is not deliberately dissipated. Sparks can become an ignition source.
They will ignite a flammable atmosphere immediately when they are in contact and can create fire and explosion.
Fire and explosion are the two main hazards of static electricity.
Besides fire and explosion, hazards of static electricity can be an electric shock to the workers. The risks can be injury and death.
Static Electricity Safety Tips
Now, we are going to learn how to control hazards of static electricity safely as well as controlling the hazards.
Here are the static electricity safety tips:
- Have a good understanding of static electricity generation and control. Provide an effective training.
- Always follow the standard operating procedure.
- Apply appropriate safety slogan to remind about the hazards of static electricity.
- Announce a list of static electricity sources: type of operations and location.
- Always wear appropriate PPE during the operation: anti-static clothing, anti-static safety shoes, anti-static gloves, etc.
- Make sure to use appropriate material for handling. Do not use a plastic container for oil or fuel, to avoid static electricity due to fluid flow.
- Beware when flowing or mixing different two different materials such as fuel and air, or flammable gas contaminated with rust.
- Using bonding technique: bonding is the process of connecting two or more conductive objects together by means of a conductor. Here is an example of bonding wire from Justrite, Justrite-08497 10′ long.
- Use proper static electricity grounding technique: earthing involves connecting one or more conductive objects to the ground.
- Have a regular check on earth grounding resistance value. Use a good tester such as Extech 382252 Ground Resistance Tester for doing this.
- Substitution involves replacing conductive materials with non-conductive ones.
- Adding a specialty chemical to increase fluid conductivity such as hydrocarbons.
- Repair immediately any flammable liquid tank or vessel, pipe.
- Prevented a vapour-air mixture through inerting (with nitrogen) and mechanical ventilation.
- Make sure you have done a complete process of hazard identification and assessing the associated risk. Repeat this regularly to avoid a miss.
 Yuqin Hu et al 2013 J. Phys.: Conf. Ser. 418 012037
 A Ohsawa 2011 J. Phys.: Conf. Ser. 301 012033