A Look Back: The Largest Loss Industrial Accident in U.S. History

A Look Back:  The Largest Loss Industrial Accident in U.S. History

"Those who cannot remember the past are condemned to repeat it," George Santayana.

Monday, February 1, 1999 - An explosion and fire at the Ford power plant in Dearborn, MI killed 6 people, injured 38, and caused $1 billion in property damage.  This was the most expensive industrial accident in U.S. history.

History

In the 1930s, the plant employed 100,000 people, assembling iron ore into cars.  By 1990, Ford began planning a new assembly complex complete with steel blast furnaces, steel rolling mills, automobile assembly plant, engine assembly plant, frame plant, a tool-and-die plant, and power plant.  In 1998, Ford decided to phase out the 78 year old power plant and replace it with a 710-megawatt facility.

Plant Design and Layout

The new plant consisted of a pulverizer building, turbo blower building, boiler building, generator building, electrical building, and boiler.  See building diagram from NFPA below.

DiagramBoiler 6, the largest capacity boiler in the complex, was the boiler involved in the explosion.  This particular boiler was designed to use pulverized coal, coke oven gas, and blast furnace gas.  All three types of fuel could be used alone or in combination.  The igniters and pilots were manually lit with an alcohol-soaked rag.

Event

At 1pm on February 1, Boiler 6 exploded, sending a fireball into the sky.  The explosion sprayed debris over the entire complex, blew out windows throughout the complex and in cars parked nearby, and cut off power to the entire complex.  Of the six stories in the building, five were ignited, smoldering for four hours.  The explosion was so powerful that it sent the engine room in the air, landing on the electrical building's roof.  The explosion blew through many windows, igniting the fuels inside other buildings, including roofing material and lube oil. 

Conclusion

Through the investigation, it was discovered that the explosion occurred when maintenance workers shut down the boiler for service.  They turned off the burners to start a nitrogen purge flow.  The gas lines were turned off and purged through the boiler.  However, one gas line was not turned off.  The gas from this line flowed into the boiler, igniting within 2 minutes.  Moments before the explosion, an employee noticed the problem, but it was too late.  Boiler 6 exploded, sending up clouds of coal dust, igniting secondary explosions.  The series of events leading up to the $1 billion in damages could have been minimized with proper inspection, testing, and maintenance.  To learn more about inspection, testing, and maintenance options click here.