04/16/2015
"SS Grandcamp" – 68 years later, what have we learned?
On 16 April, 1947, the "SS Grandcamp" cargo ship exploded while at harbor in Texas City, Texas. Best estimate is that 561 people died as a result of the explosion, with over 5,000 injured. Over 1,000 buildings in the area were leveled, while the blast broke windows in Houston, 40 miles away, and was felt over 200 miles away in Louisiana.
This is a defining event in the history of ammonium nitrate fertilizer handling and storage. The "SS Grandcamp" incident still ranks as the deadliest industrial accident in US history and one of the deadliest in the world.
The fire started in a hold around 8am. The hold next to that contained 2,300 tons of ammonium nitrate in bags. Firefighting efforts by volunteer firefighters and the ships’ crew were unable to contain or control the initial fire. The ship's captain ordered the hold to be sealed and steamed out in an effort to quench the fire – a reasonable technique for typical combustible fires, but one that did little to resolve the fire in the hold.
Around 9am, an hour after the fire started, the sea water outside the hold was observed to be boiling, while water sprayed onto the side of the ship was seen to vaporize instantly. Witnesses also report that the ship's deck was starting to bulge – likely due to a combination of extreme heat from the fire and pressure from the steam.
At 9:12am, with the firefighting efforts in full force, the nitrate in the hold detonated. The ship was destroyed and a huge blast wave rolled outwards. Everyone on board the ship and in the immediate vicinity, including 27 volunteer firefighters and a large crowd of spectators, was killed instantly. Many bodies were vaporized and the final death toll has never been determined with certainty. One of the ship's anchors, weighing 2 tons, landed 1.6 miles away. The blast wave and burning debris from the explosion caused widespread damage and secondary fires. One of these fires was aboard the "High Flyer", another ship loaded with ammonium nitrate, which detonated in the early hours of the following day, claiming at least two more lives and causing additional damage.
So what are some of the key Lessons from the "SS Grandcamp" explosion? First, this incident highlighted the fact, not widely understood at the time, that ammonium nitrate is explosive under the right conditions. While contamination with organic material is generally known to be a major risk factor, additional factors include moisture and pressure – both introduced by sealing and steaming the hold.
Second, the incident stresses the importance of knowing the hazards of materials being stored, transported or handled. Ships’ manifests today include extensive details, such as the information available in Safety Data Sheet. Safety data sheets include information on the hazards to safety, health and the environment, as well as information on the fire and explosion risks of the material and appropriate firefighting measures.
Third, the importance of emergency plans, which should include evacuation & exclusion zones for credible events as well as specific actions to be taken – or to be avoided – in dealing with an emergency.
The "SS Grandcamp" incident could have been avoided entirely by better storage and handling practices driven by a thorough understanding of the hazards. The death toll could have been avoided by an understanding of the potential consequences of a fire involving ammonium nitrate, which could have driven different techniques to combat the fire and prompt action to evacuate the area.
The "SS Grandcamp" was not the first major industrial accident involving ammonium nitrate. Another “classic” was the 1921 explosion in a fertilizer factory in Germany, which resulted in a similar death toll, left 6,500 people homeless, and a crater 65 feet deep by 300-400 feet across.
Unfortunately, Texas City was not the last accidental explosion involving ammonium nitrate due to fire. On 17 April, 2013, an explosion at a fertilizer redistribution facility in West, Texas, killed 15 people and injured more than 160, in addition to destroying an apartment building and damaging a nearby school and nursing home, among others. As with the Texas City event 66 years and one day prior, the West explosion started with a fire and claimed the lives of the brave volunteer firefighters attempting to deal with it.
Do you understand the hazards at your site or workplace? Do you know how to minimize the risks through good design and management? Finally, do you know how to best deal with credible emergencies, such as a fire or a loss of containment, without putting people in harm’s way? If you cannot answer all three with a solid “yes”, get help to find the answers. While Monarch SMS is available to help, you can also get a lot of excellent information from industry associations and your insurance carrier, to name just two sources.
