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Barton Solvents Flammable Liquid Explosion and Fire

Overview

On October 29, 2007, at about 1 p.m., a fire and series of explosions occurred at the Barton Solvents Des Moines, Iowa, chemical distribution facility. The initial fire started in the packaging area while a 300-gallon portable steel tank, known as a tote, was being filled with ethyl acetate, a flammable solvent. The CSB published this Case Study to underscore the need for effective bonding and grounding and for fire protection practices when handling flammable liquids.

Incident Snapshot

Field Value
Facility / Company Barton Solvents
Location Des Moines, IA
Incident Date 10/29/2007
Investigation Status The CSB completed its investigation on September 18, 2008, and issued a case study report.
Accident Type Chemical Distribution - Fire and Explosion
Final Report Release Date 09/18/2008

What Happened

  • An operator placed the fill nozzle in the fill opening on top of the tote and suspended a steel weight on the nozzle to keep it in place.
  • After opening the valve to begin the filling process, the operator walked across the room to do other work.
  • As the tote was filling, he heard a popping sound and turned to see the tote engulfed in flames and the fill nozzle laying on the floor discharging ethyl acetate.
  • Before evacuating, employees tried unsuccessfully to extinguish the fire with a handheld fire extinguisher.
  • The fire spread rapidly to the wood-framed warehouse, igniting a large volume of flammable and combustible liquids.
  • A large plume of smoke and rocketing barrels and debris triggered an evacuation of the businesses surrounding the facility.

Facility and Process Context

  • Barton Solvents Des Moines, Iowa, chemical distribution facility.
  • The packaging area was adjoined to the flammable storage warehouse.
  • A wall separating the two areas was not fire-rated, and large non-fire-rated doors between the warehouse and packaging area were kept open and were not equipped with self-closing mechanisms.
  • The warehouse had an automatic sprinkler system, which did not extend into the packaging area where flammable liquids were routinely stored.
  • At the time of the fire, several 55-gallon drums and approximately 30 smaller containers (i.e., 1-5 gallons) of flammable liquids were stored in the packaging area.

Consequences

  • Fatalities: None reported.
  • Injuries: One employee received minor injuries and one firefighter was treated for a heat-related illness.
  • Environmental Release: Not reported.
  • Facility Damage: The main warehouse structure was destroyed.
  • Operational Impact: Barton’s business was significantly interrupted.

Key Findings

Immediate Causes

  • A static discharge (spark) between the tote body and a metal component on the fill nozzle/hose assembly, which included the steel weight, likely ignited the vapor-air mixture.
  • Static electricity likely accumulated on these parts and sparked to the stainless steel tote body, igniting the vapor that accumulated around the fill opening during filling.

Contributing Factors

  • An ignitable vapor-air mixture formed near the tote fill opening.
  • The steel parts of the fill nozzle and hose assembly (and the steel weight) were not bonded and grounded.
  • The metal components of the nozzle, the synthetic rubber fill hose, and the pump were not bonded to the tote.
  • The nozzle was made of nonconductive plastic, but it housed a stainless steel ball valve and was fitted with a steel quick-connect fitting.
  • The steel weight was intended to prevent the nozzle from being ejected from the tote during filling.
  • All these conductive objects were isolated from ground and were susceptible to static accumulation and discharge.
  • The manufacturer’s technical documentation for the nozzle and hose revealed that they were not intended for flammable service.
  • Barton top-filled (splash-filled) its totes and drums in the packaging area.
  • Ungrounded metal parts on the fill equipment likely accumulated a static charge and sparked to the external wall of the steel tote, igniting the vapors around the fill opening.
  • The packaging area was adjoined to the flammable storage warehouse.
  • The wall separating the two areas was not fire-rated.
  • Large non-fire-rated doors between the warehouse and packaging area were kept open and were not equipped with self-closing mechanisms.
  • The warehouse sprinkler system activated after the fire had gained momentum in the packaging area, but was incapable of extinguishing the blaze.

Organizational and Systemic Factors

  • Barton’s property insurance company had recently recommended that Barton install an automatic fire suppression system in the packaging area.
  • If Barton had implemented a comprehensive static electricity and flammable liquid safety program in compliance with current regulatory standards and good practice guidance, this incident likely would have been prevented.

Failed Safeguards or Barrier Breakdowns

  • The fill nozzle and hose used at Barton were not designed to be bonded and grounded, and were not intended for flammable service.
  • The local exhaust ventilation system to remove vapors generated during filling operations was available, but was not turned on at the time of the incident.
  • The warehouse sprinkler system did not extend into the packaging area.
  • A fire suppression system in the packaging area was not installed.
  • The wall separating the packaging area and the flammable storage warehouse was not fire-rated.
  • The large non-fire-rated doors between the warehouse and packaging area were kept open and were not equipped with self-closing mechanisms.
  • The operator attached a grounding clamp to the tote before he started filling it, however, the metal components of the nozzle, the synthetic rubber fill hose, and the pump were not bonded to the tote.

Recommendations

  1. Recommendation ID: Not specified. Recipient: Not specified. Status: Not specified. Summary: Ensure that equipment such as fill nozzles and hoses are bonded and grounded and designed for flammable service.
  2. Recommendation ID: Not specified. Recipient: Not specified. Status: Not specified. Summary: Use bonded and grounded metal dip pipes when top-filling portable tanks.
  3. Recommendation ID: Not specified. Recipient: Not specified. Status: Not specified. Summary: Install fire suppression systems in flammable packaging areas.
  4. Recommendation ID: Not specified. Recipient: Not specified. Status: Not specified. Summary: Separate flammable packaging from bulk storage areas.

Key Engineering Lessons

  • Bonding and grounding must include all conductive components in the filling assembly, not only the receiving vessel.
  • Top-filling or splash-filling flammable liquids can create ignitable vapor-air mixtures at the fill opening.
  • Equipment used for flammable service should be specifically designed for that purpose.
  • Fire protection in packaging areas should not rely solely on suppression systems located in adjacent storage areas.
  • Physical separation between flammable packaging and bulk storage should include fire-rated barriers and controlled openings.

Source Notes

  • Consolidated from a single source document: FINAL REPORT: Case Study (source_priority 1).
  • All facts were taken directly from the provided extract; no external information was added.
  • Schema fields not explicitly stated in the source were left blank.
  • https://www.csb.gov/barton-solvents-flammable-liquid-explosion-and-fire/

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