Justrite's Guide to Safety Grounding & Bonding Practices

1. What is the Purpose of Grounding and Bonding?

When working with flammable liquids, safety needs to always be top of mind. You must ground containers when dispensing Class I flammable liquids between containers. As an industry best practice, Class II and Class III liquids should be grounded when heated within 30°F from a storage or process condition. As the example above illustrates, it’s easy for a spark of static to cause a flash fire. The purpose of grounding and bonding is to keep that from occurring, by providing a conductive pathway between transfer and dispensing containers and the ground.

Grounding all containers to an earth source is recommended to prevent the buildup of static electricity. Attach grounding cables on any drums in use to an earth source for as long as the drum is in use. This provides a pathway for the electric charge to the earth, where it safely dissipates.

When dispensing liquid into another container, use bonding wire to connect the dispensing container and the receiving container. This ensures both containers have the same static electric potential and prevents the formation of sparks.

For grounding or bonding to be effective, there must be a metal-to-metal connection. Even small amounts of paint, rust or dirt around the attachment may affect the quality of the connection.

2. Do I Need to Ground All Flammable Liquid Safety Cabinets?

There are no regulations or codes that require grounding a safety cabinet. But, it is critical to do so if you are dispensing Class 1 flammable liquids from inside the cabinet. Not only could the inside of the cabinet rapidly fill with ignitable vapors, the cabinet also has a large metal surface and metal shelves to discharge static against.

All Justrite safety cabinets come with exterior grounding lugs in place to connect with a ground wire to a ground source. Connect a ground wire between all containers used to transfer liquids and someplace inside the cabinet, like a shelf hook or vent hole.

It is also an industry best practice to ground the cabinet otherwise.

3. Do I Need to Ground Hazardous Material Safety Cabinets?

When conditions exist where ignitable vapors, flammable gases, combustible dusts can be ignited by static, static management should be utilized. Safety assessments should be made by a qualified individual to determine if grounding the cabinet is required.

4. Is Grounding and Bonding Required when Transferring Flammable Liquids Between Containers?

Here is what OSHA 1910.106(e)(6)(ii) states regarding grounding:

Category 1 or 2 flammable liquids, or Category 3 flammable liquids with a flashpoint below 100 F (37.8 C), shall not be dispensed into containers unless the nozzle and container are electrically interconnected. Where the metallic floorplate on which the container stands while filling is electrically connected to the fill stem or where the fill stem is bonded to the container during filling operations by means of a bond wire, the provisions of this section shall be deemed to have been complied with.

In summation, you must ground and bond all containers of liquids with a flashpoint of 100°F or less. Note: The flexible nozzle of a Type II safety can is an effective bonding connection.

5. What Part does a Flame Arrester Play in Bonding and Grounding?

Flame arresters are an important safety feature to prevent ignition of ignitable vapors inside a safety can. They are also integral to the bonding or grounding circuit when ground or bond wires are attached to the outside of safety cans.

6. What are the Requirements for a Bonding and Grounding Cable?

Ground/bond wires are not specified by the current-carrying compacity. Braided or stranded wires offer robust strength and dependability when frequently connected and disconnected. Justrite uses airplane cable. Use strong clamps with sharp bite or teeth to ensure a good metal-to-metal connection When testing ground and bond circuits, a resistance of 1 megohm (10 to the 6th power) or less is considered adequate per NFPA 77. Helpful Tip: For complete confidence in the connection, sand off all painted surfaces.

7. How do I Ground and Bond Plastic Drums During Transfer?

Plastic drums do not conduct electricity, but static electricity may still build up on the surface of the plastic or in the flammable liquid itself.

Justrite discourages using plastic drums and containers for flammable and combustible liquids, unless provisions to manage static are incorporated into the design or the transfer process risks are fully assessed. Always consult NFPA 77: Recommended Practice on Static Electricity.

To manage static electricity when dispensing flammable liquids into plastic drums, use Justrite’s Large Steel Drum Funnel with a 32-Inch Flame Arrester. The full-length brass flame arrester minimizes splashing, friction, and the buildup of static in the fluid. When properly connected by grounding or bonding wires, the funnel keeps the fluid at the proper static potential. Sit plastic drums on a grounded metal plate to dissipate surface static on the outside of the plastic drum.

8. How do I Bond Plastic Safety Cans?

Plastic or polyethylene safety cans are popular because of their resistance to corrosion and chemical attack. They are also less susceptible to dents, punctures and chips than metal cans. Justrite’s non-metallic safety cans feature a carbon impregnated insert creating a conductive path between the stainless-steel handle assembly and the stainless-steel flame arrester inside of the pour spout. A convenient place label on the handle is suitable for making a ground/bond wire connection between it and another container.

For a downloadable PDF of this Guide, click here.

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References
“Bonding and Grounding: Quick Tips #255.” Grainger, https://www.grainger.com/content/qt-safety-bonding-grounding-255
“Flammable Liquid Storage and Handling: Quick Tips 179.” Grainger, https://www.grainger.com/content/qt-safety-flammables-combustibles-179
“How do I Work Safely with Flammable and Combustible Liquids (Static Electricity)?” Canadian Centre for Occupational Health and Safety, https://www.ccohs.ca/oshanswers/prevention/flammable_static.html
O’Brien, Mike. “Static Grounding – Dangerous, Preventable.” Plant Engineering, 15 Nov. 2010, https://www.plantengineering.com/articles/staticgrounding-dangerous-prev...
Patterson, Ryan. “Drawing Toluene into an ungrounded metal bucket.” Newson Gale, https://newson-gale.com/case-study/ungroundedmetal-bucket/
Witherspoon, Renee. “Static Electricity and Flammable Liquid Safety.” ASSP – South Plains Chapter, https://southplains.assp.org/aeolusnews/static-electricity-and-flammable...