Common Questions on Flammable and Combustible Materials

By: Lisa Neuberger

Publication: HazSafety Training Advisor Newsletter

Date Posted: 04/23/2018

Look around your workplace, and chances are you’ll find flammable and combustible materials. Examples include paints, aerosols, solvents, cleaners, oils … just to name a few. Anyone working with one of these substances needs training on how to work safely with it, including how to protect themselves from its hazards (such as flammability).

But even with training, questions come up. Here are a few of the most common questions.


Q: Can flammable liquids be stored in plastic containers?

A: Flammable and combustible liquids must be stored in “approved” containers. This includes:

  • DOT-approved shipping containers, or
  • Containers that are listed and labeled with an approval from a nationally-recognized testing laboratory (NRTL).

That said, any plastic containers used for flammable liquids must be approved by DOT or an NRTL.


Q: What about portable gas cans in the workplace?

A: OSHA generally expects all flammable liquids to be stored in a flammable storage cabinet, inside a storage room, or flammable storage warehouse. You are allowed to have enough flammable liquid for a single shift or a day of work outside the protected storage.

However, there is an exemption for incidental storage. OSHA allows you to store up to 25 gallons of Category 1 and 120 gallons of Categories 2, 3, and 4 in containers and any one “fire area” of the facility outside of the flammable cabinet or storage room.


Q: Can flammable liquids and corrosive chemicals be kept in the same storage cabinet?

A: First, check the Safety Data Sheets (SDS) for the chemicals’ specific storage requirements. The SDS will identify incompatible materials that should not be stored together. Then, if the chemicals are not incompatible, make sure the chemicals are being stored:

  • According to the manufacturer’s directions;
  • In approved containers; and
  • Inside an approved storage cabinet.


Q: What is the distance a flammable storage container can be from an exit door?

A: There’s no rule giving a specific distance that flammables must be stored from an exit door. However, OSHA does have a rule saying that:

  • Flammable liquids must not be stored where they limit the use of the exit; and
  • When using exits, employees must not have to travel toward a high hazard area.

Q: Does OSHA have a rule about storing and disposing oily rags?

A: Yes. OSHA says that oily rags (sometimes called industrial wipes, wipers, shop rags, etc.) and other combustible waste materials in a building or operating area must be:

  • Kept to a minimum,
  • Stored in closed metal waste cans, and
  • Disposed of daily.

Oily or solvent-soaked rags can easily start a fire through spontaneous combustion. Prevent this by using specially designed oily waste cans for temporary storage. These cans have spring-loaded lids and raised bottoms with vent holes to dispense heat.

Remove flammable liquids from the rags before placing them in the temporary containers. Drain cans and liquid disposal cans offer the greatest degree of safety at your workstation.

About the author
Lisa Neuberger - EH&S Editor

Lisa joined J. J. Keller & Associates, Inc. in 2008. She serves as a resource for customers on environmental, health, and safety topics, and has a passion for the safe management of hazardous waste. She specializes in OSHA’s workplace injury and illness recordkeeping and reporting, flammable liquids, and sanitation standards and in EPA’s solid and hazardous waste regulations.

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