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Praxair Flammable Gas Cylinder Fire

Overview

On June 24, 2005, fire swept through thousands of flammable gas cylinders at the Praxair gas repackaging plant in St. Louis, Missouri. Dozens of exploding cylinders were launched into the surrounding community and struck nearby homes, buildings, and cars. Extensive damage was caused, and several small fires were started. The facility was located in a commercial and residential area near Lafayette Square and stored about 30,000 compressed gas cylinders onsite.

Incident Snapshot

Field Value
Facility / Company Praxair
Location St. Louis, MO
Incident Date 06/24/2005
Investigation Status The Board issued a Safety Bulletin on this report at a news conference in St. Louis on June 15, 2006.
Accident Type Chemical Distribution - Fire and Explosion
Final Report Release Date 06/15/2006

What Happened

  • About 3:20 pm, a technician retrieving cylinders from an outside storage area saw a ten-foot high flame coming from a cylinder and activated the fire alarm.
  • Security camera video from the facility shows the release and ignition of gas from a cylinder in the propylene return area.
  • As workers and customers evacuated, the fire spread to adjacent cylinders.
  • Security camera video shows nearby cylinders igniting in the first minute.
  • At 2 minutes, cylinders begin exploding, flying into other areas of the facility, and spreading the fire.
  • After 4 minutes, the fire covers most of the facility’s flammable gas cylinder area and explosions are frequent.
  • The St. Louis Fire Department arrived at about 3:35 pm. By this time, a large number of flammable gas cylinders were already involved in the fire.
  • Firefighters set up a five-block perimeter, evacuated local residents, directed a water stream on the fire, and extinguished secondary fires started by cylinders propelled offsite.
  • The fire was finally controlled at about 8:30 pm.

Facility and Process Context

  • The St. Louis Praxair Distribution site fills and distributes liquefied and compressed gas cylinders, rents welding machinery, and sells welding supplies.
  • Praxair has about 30,000 compressed gas cylinders containing oxygen, nitrogen, propane, propylene, acetylene, carbon dioxide, helium, and other specialty gases onsite.
  • The facility employs about 70.
  • The facility is located in a commercial and residential area near Lafayette Square.
  • Praxair divided the cylinder storage into “full” and “empty” or “returned” sections.
  • The “returned” section, where the fire originated, is for cylinders returned for refilling, which may not always be empty when returned.

Consequences

  • Fatalities: The St. Louis Chief Medical Examiner attributed the death of one St. Louis resident to an asthma attack triggered by noxious smoke and fumes from the incident.
  • Injuries: Not reported in the provided extract.
  • Environmental release: The fire plume spread asbestos from ruptured acetylene cylinders over a 1/3-mile wide and 1-mile long area.
  • Facility damage: The facility was damaged extensively by fire and water. A corner of the main production building and store area was heavily fire-damaged. Inside, the office and store areas were water- and smoke-damaged. In all, the fire consumed nearly the entire inventory of flammable gas, or about 8,000 cylinders.
  • Operational impact: The fire could not be extinguished until most of the flammable gas cylinders were expended. The fire was finally controlled at about 8:30 pm.

Key Findings

Immediate Causes

  • Direct sunlight and radiant heat from asphalt paving heated returned propylene cylinders.
  • As the cylinder wall temperatures rose, the internal pressures increased causing the relief device on a cylinder valve to open and vent propylene.
  • The venting propylene ignited, most likely from a static discharge, at about 3:20 pm.

Contributing Factors

  • High ambient temperature limited natural air-cooling of the cylinders.
  • The returned cylinders, containing less gas than full cylinders, heated at a faster rate than full cylinders.
  • An adjacent cylinder, further heated by the fire, released propylene, and caught fire.
  • The growing fire heated additional cylinders, which released more propylene into the fire.
  • The fire’s intensity continued to raise cylinder temperatures, softening the steel and rupturing the cylinders.
  • The fire spread to a group of acetylene cylinders.
  • The liquefied petroleum gas area of the facility became fully involved in the fire.
  • Ruptured cylinders (acetylene, propane, and propylene) rocketed into the community, damaging buildings and starting several vehicle fires.
  • St. Louis Fire Department arrived at about 3:35 pm, established an unmanned water spray on the fire, and retreated to a safe distance.
  • The fire department did not actively fight the main fire due to the danger of rocketing cylinders.
  • High ambient temperatures, in combination with low relief valve opening pressure, increase the risk of catastrophic fires at facilities handling propylene cylinders.

Organizational and Systemic Factors

  • Praxair’s procedures allowed 22 employees and two customers to evacuate safely in accordance with Praxair’s procedures.
  • The CSB used physical evidence, surveillance video recording, interviews, and information from Praxair’s internal investigation to establish the likely failure sequence.

Failed Safeguards or Barrier Breakdowns

  • The facility did not prevent spontaneous venting of propylene cylinders exposed to high temperatures and direct sunlight.
  • The facility did not prevent the fire from spreading to adjacent cylinders.
  • The facility did not prevent exploding cylinders from flying into the community.
  • The facility did not extinguish the fire until most of the flammable gas cylinders were expended.

Recommendations

  1. 2005-I-MO-R1 | Recipient: Compressed Gas Association (CGA) | Status: Not specified | Summary: Communicate with your members who operate gas repackaging facilities the details of this incident and the best practices for handling and storing cylinders.
  2. 2005-I-MO-R2 | Recipient: Compressed Gas Association (CGA) | Status: Not specified | Summary: Revise CGA standards for the CG-7 relief valves used in propylene service to require: 1) a greater margin between vapor pressure and relief valve setpoint (similar to propane); and 2) that valves be capable of multiple operations within the specified setpoint tolerance or be furnished with an indicator that alerts users that the valve has operated.

Key Engineering Lessons

  • When exposed to high temperatures and direct sunlight, propylene cylinders can spontaneously vent through their relief devices, releasing propylene that can ignite and create a domino effect across adjacent cylinders.
  • A small fire from one propylene cylinder can spread to other propylene cylinders and then to propane and acetylene cylinders.
  • High ambient temperatures, combined with low relief valve opening pressure, increase the risk of catastrophic fires at facilities handling propylene cylinders.
  • CG-7 relief valves used in propylene service should provide a greater margin between vapor pressure and relief valve setpoint and should either be capable of multiple operations within tolerance or provide an indicator that the valve has operated.

Source Notes

  • Consolidated from a single source document: FINAL REPORT: Safety Bulletin (source_priority 1).
  • All facts are taken directly from the provided structured extract; no external information was added.
  • https://www.csb.gov/praxair-flammable-gas-cylinder-fire/

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