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Barton Solvents Explosions and Fire

Overview

On July 17, 2007, at about 9 a.m., an explosion and fire occurred at the Barton Solvents Wichita facility in Valley Center, Kansas. The initial explosion occurred inside a vertical above-ground storage tank being filled with Varnish Makers’ and Painters’ (VM&P) naphtha. The incident triggered an evacuation of Valley Center, destroyed the tank farm, caused projectile damage offsite, and significantly interrupted Barton’s business.

Incident Snapshot

Field Value
Facility / Company Barton Solvents
Location Valley Center, KS
Incident Date 07/17/2007
Investigation Status The CSB's final report was issued at a news conference in Wichita, Kansas, on June 26, 2008.
Accident Type Chemical Distribution - Fire and Explosion Investigation
Final Report Release Date 06/26/2008

What Happened

  • On July 17, 2007, at about 9 a.m., an explosion and fire occurred at the Barton Solvents Wichita facility in Valley Center, Kansas.
  • The initial explosion occurred soon after the tank farm supervisor started the transfer of the final compartment of a tanker-trailer containing VM&P naphtha into a 15,000 gallon above-ground storage tank.
  • The explosion sent the VM&P tank rocketing into the air, trailing a cloud of smoke and fire from the burning liquid; it landed approximately 130 feet away.
  • Within moments, two more tanks ruptured and released their contents into the rapidly escalating fire that was concentrated inside the earthen spill containment area surrounding the tank farm.
  • As the fire burned, the contents of other tanks over-pressurized or ignited, launching steel tank tops, vent valves, pipes, and steel parts off-site and into the adjoining community.

Facility and Process Context

  • Barton Solvents Wichita facility in Valley Center, Kansas
  • Tank farm
  • Vertical above-ground storage tank
  • 15,000 gallon above-ground storage tank
  • Earthen spill containment area surrounding the tank farm
  • The tank farm included 43 above-ground storage tanks with capacities ranging from 3,000 to 20,000 gallons.
  • Tank heights ranged from approximately 15 to 40 feet.

Consequences

  • Fatalities: None reported.
  • Injuries: Eleven residents and one firefighter received medical treatment.
  • Environmental release: Approximately 20,000 gallons of flammable liquid were released into the spill containment.
  • Facility damage: Destroyed the tank farm; the VM&P tank rocketed into the air and landed approximately 130 feet away; two more tanks ruptured; other tanks over-pressurized or ignited; steel tank tops, vent valves, pipes, and steel parts were launched off-site.
  • Operational impact: Significantly interrupted Barton’s business; the incident triggered an evacuation of Valley Center (approximately 6,000 residents).

Key Findings

Immediate Causes

  • The tank contained an ignitable vapor-air mixture in its head space.
  • Stop-start filling, air in the transfer piping, and sediment and water (likely present in the tank) caused a rapid static charge accumulation inside the VM&P naphtha tank.
  • The tank had a liquid level gauging system float with a loose linkage that likely separated and created a spark during filling.

Contributing Factors

  • VM&P naphtha is a National Fire Protection Association (NFPA) Class IB flammable liquid that can produce ignitable vapor-air mixtures inside tanks and, because of its low electrical conductivity, can accumulate dangerous levels of static electricity.
  • Static electricity is generated as liquid flows through pipes, valves, and filters while being transferred.
  • Nonconductive liquids, such as VM&P naphtha and other flammable liquids, dissipate static electricity slowly.
  • The transfer hose was severely damaged during the fire, which prevented investigators from determining if bonding/grounding was effective.
  • According to witnesses at Barton, the tanker-trailer, pump, piping, and storage tank were bonded and grounded at the time of the incident.
  • Barton indicated that it had no records of the VM&P tank ever being cleaned, and the tank had no manway or access opening to facilitate cleaning.
  • Air pockets were introduced into the fill piping, and then transferred into the tank when the transfer hose was reconnected to the tanker-trailer after compartments were changed.
  • The static electricity accumulation was likely exacerbated by the air pockets (bubbling) and the likely presence of suspended sediment and water in the tank.
  • The VM&P tank was approximately 30 percent filled at the time of the explosion, which would have produced a liquid surface potential (voltage) close to the maximum expected during filling.
  • The MSDS for the VM&P naphtha involved in this incident did not adequately communicate the explosive hazard.

Organizational and Systemic Factors

  • The MSDSs supplied by the manufacturer of the Barton VM&P naphtha indicated that the material may accumulate a static electrical charge that could discharge and ignite accumulated vapors.
  • It did not, however, provide critical physical and chemical property data and warnings that the material may form an ignitable vapor-air mixture inside storage tanks.
  • Nor did it list any precautionary measures, beyond normal bonding and grounding practices, or reference relevant consensus guidance that Barton could have used to help prevent this explosion.
  • MSDSs do not typically communicate critical physical and chemical properties, and specific precautions or reference guidance for flammable liquids that may pose a static ignition hazard.
  • Of the 62 MSDSs reviewed, only one specifically warned of the potential for the material to form an ignitable vapor-air mixture inside a storage tank.
  • Only seven indicated that bonding and grounding alone may not be enough to prevent a static discharge.
  • Only eight of the 62 provided one or more specific precautionary measures.
  • Only three MSDSs included conductivity testing data.
  • The safety data sheet (SDS) did not provide critical physical and chemical property data that would warn that the material may form an ignitable vapor-air mixture inside storage tanks.
  • The SDS did not list any precautionary measures, beyond normal bonding and grounding practices, or reference relevant consensus guidance.
  • The GHS did not provide identification criteria or warning guidance for liquids that, in addition to being ignitable inside tanks at ambient temperatures, also accumulate static electricity that can ignite them.
  • The GHS does not require a preparer to include conductivity testing data in an SDS.

Failed Safeguards or Barrier Breakdowns

  • Bonding and grounding
  • Liquid level gauging system float with a loose linkage
  • MSDS hazard communication
  • Transfer hose
  • Tank cleaning / sediment removal
  • Normal bonding and grounding may not be enough
  • Critical physical and chemical property data on the SDS
  • Precautionary measures beyond normal bonding and grounding practices
  • Reference to relevant consensus guidance
  • Conductivity testing data in an SDS

Recommendations

  1. 2007-06-I-KS-R1 — Recipient: Occupational Safety and Health Administration — Status: Open — Summary: Revise the “Guidance for Hazard Determination for compliance with the OSHA Hazard Communication Standard” to advise chemical manufacturers and importers that prepare MSDSs to evaluate flammable liquids to determine their potential to accumulate static electricity and test the conductivity of the flammable liquid and include the testing results in the MSDS.
  2. 2007-06-I-KS-R2 — Recipient: Occupational Safety and Health Administration — Status: Closed – Acceptable Action — Summary: Prior to the next revision, communicate to the Sub-Committee on the Globally Harmonized System of Classification and Labeling of Chemicals (SCEGHS) the need to amend the GHS to advise chemical manufacturers and importers that prepare MSDSs to identify and include a warning for materials that are static accumulators and that may form ignitable vapor-air mixtures in storage tanks; advise users that bonding and grounding may be insufficient to eliminate the hazard from static-accumulating flammable liquids, and provide examples of additional precautions and references to the relevant consensus guidance (e.g., NFPA 77, Recommended Practice on Static Electricity (2007), and API Recommended Practice 2003, Protection Against Ignitions Arising Out of Static, Lightning, and Stray Currents (2008)); provide conductivity testing data for materials that are static accumulators and that may form ignitable vapor-air mixtures in storage tanks.
  3. 2007-06-I-KS-R3 — Recipient: American National Standards Institute (ANSI) Z400.1 Committee — Status: Open — Summary: Revise ANSI Z400.1 to advise chemical manufacturers and importers that prepare MSDSs to identify and include a warning for materials that are static-accumulators and that may form ignitable vapor-air mixtures in storage tanks; advise users that bonding and grounding may be insufficient to eliminate the hazard from static-accumulating flammable liquids, and provide examples of additional precautions and references to the relevant consensus guidance (e.g., NFPA 77, Recommended Practice on Static Electricity (2007), and API Recommended Practice 2003, Protection Against Ignitions Arising Out of Static, Lightning, and Stray Currents (2008)); and provide conductivity testing data for materials that are static accumulators and that may
  4. 2007-06-I-KS-R4 — Recipient: American Chemistry Council — Status: Open — Summary:
  5. 2007-06-I-KS-R5 — Recipient: American Petroleum Institute — Status: Open — Summary:
  6. 2007-06-I-KS-R6 — Recipient: National Association of Chemical Distributors — Status: Open — Summary:
  7. 2007-06-I-KS-R7 — Recipient: National Paint and Coatings Association — Status: Open — Summary:
  8. 2007-06-I-KS-R8 — Recipient: National Petrochemical and Refiners Association — Status: Open — Summary:
  9. 2007-06-I-KS-R9 — Recipient: Society for Chemical Hazard Communication — Status: Open — Summary: Recommend to your membership companies that prepare MSDSs to update the MSDSs to identify and include a warning for materials that are static accumulators and that may include a statement that bonding and grounding may be insufficient to eliminate the hazard from static-accumulating flammable liquids, and provide examples of additional precautions and references to the relevant consensus guidance (e.g., NFPA 77, Recommended Practice on Static Electricity (2007), and API Recommended Practice 2003, Protection Against Ignitions Arising Out of Static, Lightning, and Stray Currents (2008)). Include conductivity testing data for the materials that are static accumulators and that may form ignitable vapor-air mixtures in storage tanks.

Key Engineering Lessons

  • Nonconductive flammable liquids can accumulate static electricity during transfer and storage.
  • Static sparks can readily ignite flammable vapor-air mixtures inside storage tanks.
  • Material Safety Data Sheets (MSDSs) often do not adequately communicate hazard data and precautions.
  • Normal bonding and grounding may not be enough.

Source Notes

  • Priority 1 final report was used as the primary authority for incident facts, causes, and recommendations.
  • Priority 4 recommendation status summary was used only to update the status of Recommendation No. 2007-6-I-KS-R2 to Closed – Acceptable Action and to corroborate selected findings.
  • Some recommendation summaries are truncated in the provided source text; truncation was preserved where necessary.

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