Static electricity is the electric charge generated when there is friction between two things made of varied materials or substances. Static electric charges can also build up when a liquid, such as petroleum, solvents, or fuels, move in contact with other materials.
This charge can occur when liquids are poured, pumped, filtered, stirred, agitated or flow through pipes or hoses. The amount of charge that develops is dependent on the quantity of liquid and how fast it flows.
Sparks generated by static electricity can be dangerous when transferring flammable liquids. Examples include transferring a flammable liquid from a tank car to a tanker truck, or simply transferring flammable paints or solvents from a drum to a metal container.
Bonding is accomplished by making an electrical connection from one metal container to another. Bonding ensures that there will be no difference in electrical potential between the two container so that sparks do not result. Containers are bonded by attaching a special metal bonding strap or wire to both containers.
Grounding is accomplished by connecting the container to an already grounded object, such as a buried metal plate, metallic underground piping system, metal water pipes, or a grounded metal building framework that will conduct electricity.
When bonding and grounding remember to:
Determine the objects that need to be bonded and grounded. This may include containers, tanks, pipes, and other conductive equipment involved in the transfer of flammable liquids.
Connect the bonding cable or system to the container or equipment being filled. This could be a flammable liquid safety can or tanker truck. The bonding cable should be securely clamped to a conductive part of the container. When loading tank cars or tanker trucks this would be a hose tube mount or grounded lug or ball.
Connect the grounding wire at a point away from the discharge opening.
Verify the bonding and grounding connections. Make sure that the connections are properly attached. If you are using a grounding system, check the grounding indicator lights to confirm the closed ground circuit.
Remember that all grounding and bonding connections must be free of dirt, paint, rust, and corrosion.
Maintain a continuous electrical connection throughout the transfer. This ensures that any static electricity that accumulates will flow safely to the ground, minimizing the risk of sparks and ignition.
Always stay within 150 feet of the cargo tank while loading or unloading with a flammable or combustible liquid.
Always follow your company’s grounding and bonding procedures. When working with flammable liquids there is little margin for error. Remember, safety doesn’t have to be difficult, simple steps, such as using grounding and bonding procedures, can prevent injuries and save lives.
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Source: Joe Mlynek is president of Progressive Safety Services LLC, Gates Mills, OH: joe.mlynek@progressivesafety.us, and content creation expert for Safety Made Simple, Inc., Olathe, KS; joe@safetymadesimple.com
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