LP-Gas Tank Explosion Kills Two Volunteer Firefighters (Carthage, Illinois - October 2, 1997) » Lessons Learned

1. The position of firefighters and apparatus should avoid tank ends, which are in-line with the long axis of the tank.

   When LP-Gas tanks BLEVE, the energy released will often propel parts of the tank in directions parallel with the long axis. Approach and firefighting positions should be perpendicular to the tank’s long axis to minimize the risk to firefighters. The Fire Chief’s plan was to position the engine behind the large grain silo to provide shielding and position handlines between the grain silo and the animal shed to the east. However, Engine 11 was stopped before it was completely behind the silo, leaving the back of the engine exposed. Although the next step in the plan was not executed, the nozzle positions would have avoided the tank ends. Options for nozzle placement to wet the entire surface of both tanks were limited because of their location. The wood frame shed obstructed access to the entire east side of the LP-Gas tanks. The burning grain dryer and tractor restricted access from the west.

2. To effectively cool LP-Gas tanks exposed to a fire and absorb the heat energy from flames impinging directly on the tank shell, a substantial water application rate is required.

   For exposure fires, the entire tank surface must be kept wet to absorb the radiant heat energy reaching the vessel. When flames are impinging on the tank, a water stream must be constantly applied at the contact point to prevent the metal from weakening and thinning out. Water flow rates of 250 to 500 gpm for the two 1,000 gallon tanks would be a recommended minimum. The high-pressure, low flow rate, pre-connected lines would not provide the necessary amount of water on the tank. Furthermore, hose lines that can be placed into operation and then left unattended are preferred over hose lines that need to be manned. It is unlikely that the pre-connected hose lines could be left operating unattended.

3. The more time the LP-Gas tank is exposed to fire conditions, especially to fire impinging on the metal shell, the greater the risk of BLEVE.

   The structural integrity - usually defined as the ability to carry the load - of anything (floor, roof, building, pressure tank, etc.) exposed to fire usually deteriorates in accordance with the length of exposure time. Long delays in beginning the application of water (cooling and suppression) from the start of fire exposure, should raise warnings about possible structural failure. In this incident, the operating pressure relief valves are indications that the LP-Gas tanks are under stress and thereby increasing the prospect of catastrophic failure (BLEVE). Long fire exposure times and operating pressure relief valves should indicate that the potential for tank failure is imminent. The incident commander should concentrate on evacuating the area parallel to the long axis of the tank and limiting exposure to firefighters and bystanders. The minimal life exposure should be a significant factor in the risk benefit analysis.

4. Tactical plans should anticipate that “portable” and “temporary” installations are not in full compliance with fire and safety codes.

   Compliance with fire and safety codes cannot be assured for equipment installed on a “temporary” or “portable” basis. Plan review and inspection of these installations is often omitted even if officials are aware of their presence. Farms and construction sites are typical locations of “portable” and “temporary” equipment installations. Fireground operations and tactics should contemplate that fire and safety code compliance is likely to be incomplete. Fire conditions, spread, and reaction may be different than your experiences from drills and previous incidents. The long LP-Gas hoses and the noncomplying tank manifold connection contributed to the failure of the east LP-Gas tank.

5. The incident commander should anticipate that not everything will occur in a predictable manner or in accordance with drill and training.

   The potentially defective weld was an invisible, unknown factor in the BLEVE. The LP-Gas tank’s general condition will usually be an unknown to the incident commander. Deficiencies in the tank’s design, construction, age, or quality of maintenance will become evident under fire and emergency conditions. Aggressive actions to cool the tank should be tempered with caution when the area around the tank can be quickly evacuated (few occupied buildings nearby) and information about the tank’s condition (before and during the incident) is limited.