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Packaging Corporation Storage Tank Explosion

Overview

On July 29, 2008, three workers died and a fourth was injured when an explosion occurred inside an 80-foot-tall storage tank at the Packaging Corporation of America (PCA) corrugated cardboard mill in Tomahawk, Wisconsin. The workers were on a catwalk above the tank and performing hot work, including welding, at the time of the explosion. The storage tank held a mixture of recycled paper pulp and water. The CSB found that the contents decomposed to form flammable hydrogen.

Incident Snapshot

Field Value
Facility / Company Packaging Corporation of America (PCA)
Location Tomahawk, WI
Incident Date 07/29/2008
Investigation Status The CSB issued a hot work safety bulletin summarizing the key findings from the investigation at a news conference on March 4, 2010.
Accident Type Hot Work - Explosion and Fire
Final Report Release Date 03/04/2010

What Happened

  • On July 29, 2008, an explosion occurred at the Packaging Corporation of America (PCA) corrugated cardboard mill in Tomahawk, Wisconsin.
  • The explosion killed three maintenance workers and injured another.
  • The CSB determined the explosion resulted from welding above an 80-foot-tall storage tank that contained highly flammable hydrogen gas.
  • At the time of the accident, PCA did not recognize waste fiber tanks as potentially hazardous or require combustible gas monitoring prior to welding nearby.

Facility and Process Context

  • Packaging Corporation of America (PCA) corrugated cardboard mill in Tomahawk, Wisconsin.
  • An 80-foot-tall storage tank containing recycled paper pulp and water.
  • The tank contents decomposed to form flammable hydrogen.
  • Hot work in, on, or near tanks that contained flammables.

Consequences

  • Three workers died.
  • One worker was injured.

Key Findings

Immediate Causes

  • Welding above an 80-foot-tall storage tank that contained highly flammable hydrogen gas.
  • Hot work ignited flammable gas or vapor.

Contributing Factors

  • PCA did not recognize waste fiber tanks as potentially hazardous.
  • PCA did not require combustible gas monitoring prior to welding nearby.
  • Failure to recognize all the locations where a flammable atmosphere could be present.
  • Absence of flammables needs to be verified before and during any hot work.
  • Proper training and calibration are essential for using gas monitors effectively.

Organizational and Systemic Factors

  • Companies need to develop comprehensive systems for controlling the hazards of hot work where flammable vapor could be present.
  • Regulators, companies, and workers should recognize that combustible gas monitoring will save lives.
  • OSHA does not require combustible gas monitoring for hot work on or near flammable storage tanks.

Failed Safeguards or Barrier Breakdowns

  • Combustible gas monitoring prior to welding nearby.
  • Hazard assessments.
  • Proper gas monitoring.
  • Recognition of waste fiber tanks as potentially hazardous.
  • Verification of the absence of flammables before and during any hot work.

Recommendations

  1. Recommendation 1
    Recipient: Not specified
    Status: Not specified
    Summary: Use Alternatives – Whenever possible, avoid hot work and consider alternative methods.

  2. Recommendation 2
    Recipient: Not specified
    Status: Not specified
    Summary: Analyze the Hazards – Prior to the initiation of hot work, perform a hazard assessment that identifies the scope of the work, potential hazards, and methods of hazard control.

  3. Recommendation 3
    Recipient: Not specified
    Status: Not specified
    Summary: Monitor the Atmosphere – Conduct effective gas monitoring in the work area using a properly calibrated combustible gas detector prior to and during hot work activities, even in areas where a flammable atmosphere is not anticipated.

  4. Recommendation 4
    Recipient: Not specified
    Status: Not specified
    Summary: Test the Area – In work areas where flammable liquids and gases are stored or handled, drain and/or purge all equipment and piping before hot work is conducted. When welding on or in the vicinity of storage tanks and other containers, properly test and if necessary continuously monitor all surrounding tanks or adjacent spaces (not just the tank or container being worked on) for the presence of flammables and eliminate potential sources of flammables.

  5. Recommendation 5
    Recipient: Not specified
    Status: Not specified
    Summary: Use Written Permits – Ensure that qualified personnel familiar with the specific site hazards review and authorize all hot work and issue permits specifically identifying the work to be conducted and the required precautions.

  6. Recommendation 6
    Recipient: Not specified
    Status: Not specified
    Summary: Train Thoroughly – Train personnel on hot work policies/procedures, proper use and calibration of combustible gas detectors, safety equipment, and job specific hazards and controls in a language understood by the workforce.

  7. Recommendation 7
    Recipient: Not specified
    Status: Not specified
    Summary: Supervise Contractors – Provide safety supervision for outside contractors conducting hot work. Inform contractors about site-specific hazards including the presence of flammable materials.

Key Engineering Lessons

  • Avoid hot work of any kind in areas handling, processing or storing flammable liquids or gases whenever possible.
  • Perform a hazard assessment before hot work to identify potential flammable atmospheres and methods of hazard control.
  • Use a properly calibrated combustible gas detector before and during hot work, even where a flammable atmosphere is not anticipated.
  • When welding on or near storage tanks and other containers, test and if necessary continuously monitor surrounding tanks or adjacent spaces, not just the vessel being worked on.
  • Drain and/or purge equipment and piping before hot work in areas where flammable liquids and gases are stored or handled.
  • Ensure qualified personnel review and authorize hot work through written permits that identify the work and required precautions.
  • Train personnel on hot work procedures and combustible gas detector use in a language understood by the workforce.

Source Notes

  • Priority 1 final report used to resolve conflicts and define the authoritative findings and recommendations.
  • Priority 4 supporting document used only to supplement incident-specific context where consistent with the final report.
  • All fields were limited to information explicitly stated in the provided source extracts.
  • https://www.csb.gov/packaging-corporation-storage-tank-explosion/

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