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Herrig Brothers Farm Propane Tank Explosion

Overview

On April 9, 1998, an 18,000-gallon propane tank exploded at the Herrig Brothers Feather Creek Farm in Albert City, Iowa. The explosion was a BLEVE. Two volunteer firefighters were killed. Seven other emergency response personnel were injured. Several buildings were damaged by the blast.

Incident Snapshot

Field Value
Facility / Company Herrig Brothers Feather Creek Farm
Location Albert City, IA
Incident Date 04/09/1998
Investigation Status The final report on this investigation was approved on June 23, 1999.
Accident Type Chemical Distribution - Fire and Explosion
Final Report Release Date 06/23/1999

What Happened

  • On the evening of the incident, eight high-school-aged teens gathered at the farm for a party.
  • At approximately 11:00 pm, one of the youths began driving an all-terrain vehicle (ATV) around the farm.
  • The ATV was heading east between the propane tank and a turkey barn when it struck two aboveground propane pipes (liquid and vapor lines).
  • The ATV damaged both the liquid and vapor lines.
  • The liquid line was completely severed from the tank at the location where it was connected to a manual shut-off valve directly beneath the tank.
  • An excess flow valve protecting the liquid line failed to function, and propane leaked out of the tank at the point of the break.
  • Within a few minutes, propane from the damaged lines ignited, most likely when it reached one of the direct-fired vaporizers approximately 37 feet away.
  • A fire, fed by the broken liquid line, began burning vigorously under the tank.
  • At 11:10 pm, the neighbor called the 911 operator to report the fire.
  • Twenty members of the Albert City Volunteer Fire Department and two Buena Vista County Sheriff Deputies were the first responders to reach the farm.
  • Upon arrival at about 11:21 pm, the fire fighters observed flames originating from two primary locations: from under the west end of the tank and from the pressure relief valve pipes located on the top of the tank.
  • At approximately 11:28 pm, as fire-fighting equipment was being moved into position, the tank exploded, scattering metal tank fragments in all directions.
  • One large piece of the tank traveled in a northwesterly direction, striking and killing two volunteer firemen.
  • Seven other emergency personnel sustained injuries as a result of the explosion.

Facility and Process Context

  • The farm raised turkeys, which were housed in seven barns.
  • Space heaters and furnaces provided heat for these turkey barns.
  • Fuel for these space heaters and furnaces was supplied by a propane storage and handling system that included the propane tank that exploded.
  • The farm, located on 14 acres in rural Iowa, housed approximately 50,000 turkeys in seven barns.
  • The propane storage and handling system included a non-fireproofed, 18,000-gallon propane tank located on the south side of the farm.
  • This tank, which was originally fabricated in 1964, was installed on the farm in 1988.
  • At the time of the incident, the tank contained approximately 10,000 gallons of propane.
  • The tank rested on two concrete saddles with the bottom of the tank located approximately 4 feet above ground level.
  • Aboveground piping from the tank ran in two directions: parallel liquid and vapor lines used for propane supply ran to the west for approximately 40 feet to the fueling truck point-of-transfer; parallel liquid and vapor lines also ran north from the tank for approximately 37 feet to two direct-fired vaporizers.
  • Neither the tank nor the aboveground piping was protected by a fence or any other barrier designed to prevent damage from vehicles.
  • There were no posted warnings for vehicles to stay out of the area immediately adjacent to the tank.
  • The area where the tank and its aboveground pipes were located was bordered on the south by a public road and on the east and west by gravel driveways.
  • Fueling truck deliveries occurred as often as every week during severe winter months.

Consequences

  • Two volunteer fire fighters were killed.
  • Seven other emergency response personnel were injured.
  • Propane leaked out of the tank at the point of the break. Propane vapor may have also leaked from the damaged vapor line.
  • Several buildings were damaged by the blast. The explosion caused approximately $240,000 damage to buildings located on the farm.
  • The fire continued to burn out of control. The tank and its associated piping were blown into at least 36 pieces.

Key Findings

Immediate Causes

  • The ATV struck the two aboveground propane pipes (liquid and vapor lines) that ran from the propane tank to direct-fired vaporizers.
  • The liquid line was completely severed from the tank at the location where it was connected to a manual shut-off valve directly beneath the tank.
  • An excess flow valve protecting the liquid line failed to function.
  • The tank exploded as a BLEVE.

Contributing Factors

  • The tank was engulfed in flames due to a leak of propane under the tank.
  • These flames created the conditions that produced the BLEVE.
  • The propane tank nor its aboveground piping were protected by a fence or any other physical barrier designed to prevent damage from vehicles.
  • The flow capacity of the outlet piping system downstream of the excess flow valve was less than the closing rating of the excess flow valve installed in the tank.
  • Fire fighters were positioned too close to the burning propane storage tank when it exploded.
  • They believed that they would be protected from an explosion if they avoided the ends of the tank.
  • The State Fire Marshal did not detect deficiencies in the design and installation of the propane storage facility.
  • The State Fire Marshal did not have a program in place to adequately monitor or inspect large propane storage facilities.
  • Some training materials provided to the fire fighters led them to believe that they would be protected from a propane tank explosion by positioning themselves to the sides of the tank and by avoiding the areas extending from the two ends of the tank.
  • Fire fighters did not adequately recognize the potential for a BLEVE and that a BLEVE can scatter tank fragments in all directions.

Organizational and Systemic Factors

  • Iowa law did not specifically designate which party -- the owner or the installer of a large propane storage facility -- was required to notify the State Fire Marshal.
  • The State Fire Marshal had no record of the system.
  • The State Fire Marshal did not have a program in place to adequately monitor or inspect large propane storage facilities.
  • The Albert City Fire Department is an all-volunteer force that covers a response area of 100 square miles and serves a population of 850.
  • Members of the department received some initial training, which varied depending upon each member’s availability to attend specific training courses.
  • Certain members of the department received some additional training on responding to LP-Gas leaks and fires.
  • Fire fighters in this incident, however, had inadequate training on recognizing the potential for a BLEVE and appropriate response procedures.

Failed Safeguards or Barrier Breakdowns

  • Neither the propane tank nor its piping were protected by a fence or any other physical barrier designed to prevent such damage.
  • The excess flow valve failed to close because the flow capacity of the outlet piping system was less than the closing rating of the excess flow valve.
  • The piping downstream of the excess flow valve did not conform to NFPA 58 requirement that the connections, or line, leading to or from any individual opening shall have greater capacity than the rated flow of the excess flow valve protecting the opening.
  • The State Fire Marshal had no record of the propane system at the farm.
  • The State Fire Marshal’s Office probably would not have uncovered both deficiencies in the installation that contributed to the incident.
  • Fire fighters did not attempt to spray the tank with water.
  • Fire fighters did not withdraw and isolate for ½ mile as recommended by IFSTA.
  • The 1996 North American Emergency Response Guidebook was not consulted in responding to the fire at the farm.

Recommendations

  1. 98-007-I-IA-R1 | Recipient: Herrig Brothers Farm | Status: Not specified | Install protection (i.e., fencing or barricades) to protect aboveground propane pipes from possible damage from vehicles.
  2. 98-007-I-IA-R2 | Recipient: Herrig Brothers Farm | Status: Not specified | Install properly sized propane outlet piping from excess flow valves.
  3. 98-007-I-IA-R3 | Recipient: Iowa State Fire Marshal | Status: Not specified | Designation by regulation of the party (such as a facility owner or installer) who is responsible for submitting planned construction or modification documents to the State Fire Marshal;
  4. 98-007-I-IA-R4 | Recipient: Iowa State Fire Marshal | Status: Not specified | Procedures for approving the plans for new or modified installations;
  5. 98-007-I-IA-R5 | Recipient: Iowa State Fire Marshal | Status: Not specified | Procedures governing the issuance and posting of permits authorizing the use of equipment;
  6. 98-007-I-IA-R6 | Recipient: Iowa State Fire Marshal | Status: Not specified | On-site inspections of new, modified, and existing propane and other Liquefied Petroleum Gas storage facilities that are covered by Iowa state law.
  7. 98-007-I-IA-R7 | Recipient: Fire Service Institute of Iowa State University | Status: Not specified | Ensure that fire fighter training materials address proper response procedures for BLEVEs.
  8. 98-007-I-IA-R8 | Recipient: National Propane Gas Association (NPGA) | Status: Not specified | Ensure that fire fighter-training materials address proper response procedures for BLEVEs.
  9. 98-007-I-IA-R9 | Recipient: National Propane Gas Association (NPGA) | Status: Not specified | Distribute the CSB findings and recommendations in this report to NPGA members.

Key Engineering Lessons

  • Aboveground propane piping should be protected from vehicle impact where vehicle access is possible.
  • Outlet piping downstream of an excess flow valve must have sufficient capacity so the valve can function as intended.
  • Physical barriers and posted warnings are important safeguards where propane tanks and piping are located near roads and driveways.
  • A propane tank fire can progress rapidly to a BLEVE, and responders must not assume that staying to the sides or away from the ends of the tank will provide protection.
  • Emergency response guidance for propane tank fires must address BLEVE hazards and fragment projection in all directions.

Source Notes

  • Priority 1 final report used as the primary authority for incident sequence, causes, consequences, and recommendations.
  • Priority 4 digest used only to supplement wording where consistent with the final report; conflicts were resolved in favor of the final report.
  • Official terminology preserved where stated, including BLEVE, excess flow valve, and LP-Gas.

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