08 Jun Spontaneous Ignition

Spontaneous Ignition

Preventing Spontaneous Ignition

Spontaneous ignition can occur without an external flame or spark when combustible materials generate heat through oxidation. If that heat cannot dissipate, temperatures can continue to rise until the material ignites. Proper storage, handling, and housekeeping are essential for preventing these fires.

Guide for Discussion

How Spontaneous Ignition Occurs

Certain materials react with oxygen and produce heat. Normally, this heat dissipates harmlessly into the surrounding air. Problems occur when contaminated or reactive materials are piled together, packed tightly, or otherwise stored where heat cannot escape.

As the temperature rises:

1. Oxidation may accelerate.
2. Additional heat is generated.
3. Heat becomes trapped within the material.
4. The material may eventually reach its ignition temperature.
5. A fire can begin without an external ignition source.

This is why spontaneous ignition may occur hours after work has stopped and sometimes when no one is present.

Materials That May Be Susceptible

Depending on workplace operations, materials presenting a spontaneous-heating hazard may include:

• Rags or cloth contaminated with certain oils.
• Rags containing oil-based paints, stains, or finishes.
• Oily work clothing or other fibrous materials.
• Paint residue and scrapings.
• Sawdust or other absorbent material contaminated with oils.
• Certain organic materials and chemicals capable of self-heating.

Always review the Safety Data Sheet (SDS) and manufacturer instructions for specific storage, handling, and disposal requirements.

Oily Rags and Waste

Improperly stored oily rags are a significant spontaneous ignition hazard.

• Place oily or combustible waste in approved containers intended for that purpose.
• Keep container lids closed except when adding or removing material.
• Do not allow oily rags to accumulate on workbenches, floors, equipment, or in ordinary trash containers.
• Locate waste containers away from ignition sources and excessive heat.
• Empty and dispose of their contents according to company procedures and applicable requirements.
• Never mix incompatible wastes.

Do not assume that placing material in just any covered container makes it safe. Use containers appropriate for the particular material and hazard.

Control Heat Buildup

Heat accumulation is a major factor in spontaneous ignition.

Keep susceptible materials away from:

• Hot machinery.
• Furnaces and heaters.
• Steam lines.
• Hot work operations.
• Direct sunlight or other significant heat sources when applicable.

Do not leave piles of contaminated absorbents, rags, or similar combustible materials where internally generated heat can accumulate.

Housekeeping and Fire Prevention

Good housekeeping is one of the most effective ways to control spontaneous ignition hazards.

• Remove combustible waste regularly.
• Keep work areas free of accumulated oily or contaminated materials.
• Use designated waste containers.
• Keep containers properly closed.
• Inspect waste-storage areas routinely.
• Clean spills promptly using the appropriate procedures and materials.
• Store chemicals and combustible materials according to their SDS requirements.
• Report unusual heating, smoke, or odors immediately.

If Material Is Heating or Smoldering

Do not handle a suspicious container or pile without considering the hazards involved.

If you notice smoke, unusual heat, a burning odor, or evidence of smoldering:

• Alert others immediately.
• Follow the facility’s emergency procedures.
• Notify your supervisor or emergency personnel.
• Keep personnel away from the affected area.
• Do not open a smoking or unusually hot container unless specifically trained and authorized to do so.
• Call emergency services when conditions warrant.

Opening or disturbing a container may introduce additional oxygen and worsen the fire.

Before Leaving the Work Area

Spontaneous ignition fires frequently develop after operations have ended. Before leaving for the day:

• Remove oily and combustible waste from work areas.
• Place contaminated rags in designated containers.
• Make sure waste-container lids are properly closed.
• Check for accumulated combustible material.
• Correct or report fire hazards.
• Follow established end-of-shift waste disposal procedures.

Remember

A fire does not always need a spark or open flame to start. Materials capable of self-heating can ignite when improperly accumulated or stored. Control combustible waste, prevent heat buildup, and maintain good housekeeping.