Welding or Cutting Drums & Tanks

An “empty” drum or tank that once held fuel, solvent or oil can be more dangerous than a full one. A small amount of residue makes vapor that fills the container. When a torch or grinder touches it, the container can explode. Workers die every year cutting the top off a drum.

Photo: steel drum being filled with water before cutting, with a warning label showing previous contents

The rule

OSHA says no welding, cutting or other hot work may be done on used drums, barrels, tanks or other containers until they’ve been cleaned so thoroughly that there are no flammable materials or substances that could give off flammable or toxic vapors. Any pipes and connections must be disconnected or blanked.

Before hot work on a container

  1. Find out what it held. Check labels and ask. Treat unknown containers as having held something flammable.
  2. Empty and clean it thoroughly, using methods suited to what it held (steam, hot water and detergent, or a professional cleaning service).
  3. Open all bungs and vents so pressure can’t build up.
  4. Test the inside with a calibrated flammable gas (LEL) meter. It should read zero. See Gas Detectors.
  5. Inert it if possible: fill with water up to just below the work area, or purge with nitrogen or CO2 following a written procedure.
  6. Get a hot work permit and have a fire watch and extinguisher ready. See Hot Work Permits.

Never cut a drum with a torch or grinder “to make a burn barrel” or for scrap unless it has been properly cleaned and tested. Even a drum that has sat open for years can hold enough vapor or residue to explode.

Safer alternatives

Larger tanks

Fuel tanks, vessels and pipelines need a formal procedure: isolation, cleaning, ventilation, continuous atmospheric monitoring and often confined space entry rules. See Confined Spaces and Permit-to-Work Systems.

Standards & references

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