Two tremendous explosions destroyed the port of Texas Citya few kilometers from Houston (TX, USA) on April 16, 1947in what is today thedeadliest industrial accident in US history: according to estimates by the Texas State Historical Association, the victims were more than 550. The civilian ships involved in the accident, the SS Grandcamp and the SS High Flyertransported various types of goods destined for the French market, including large quantities of ammonium nitrate: precisely this chemical compound, used as a fertilizer in agriculturewas behind the two detonations that caused victims, injuries and extensive damage to the entire city.
The first explosion on Grandcamp
There Grandcamp was a US-made cargo ship, used for i supplies to the allies during the Second World War, recommissioned and donated to the French government at the end of the conflict.
At 8am on 16 April 1947 the workers resumed loading operations on the ship, which included 2300 tons of ammonium nitrate. Almost immediately the loading staff noticed a start of fire in the holds: a first attempt was made to extinguish it with small quantities of water interrupted by the captain of the ship, worried by the possibility of damaging the load. It was therefore decided to close the hold and use steam to try to suffocate the fire, but without success.
At 8.30am the loading personnel were evacuated and removed from the area: these workers were among the few to save themselves from the subsequent consequences. However, the ship’s crew remained nearby, together with firefighters and local volunteers (a team of 26 people) called to extinguish the fire.
Between 8.45am and 9amas evidenced by some photos, a noise was already rising from the ship thick reddish smoke indicative of the extent of the fire, with the metal walls of the hold like this incandescent to do evaporate the water of fire hoses.
THE’sudden explosion at 9:12 (actually a rapid succession of at least two explosions) swept the port area with extreme violence: its effects, with broken glass and loud bangswere also heard in the city of Galveston 16 km and in some areas of Baytown 25 km, favored by shock wave propagation through the waters of the canal.
All local fire personnel and Grandcamp crew, excluding 7 people, perished at this momenttogether with other workers from the port area and nearby factories. Unfortunately, too many people from the residential area, who had approached the area intrigued by the smoke and commotion were overwhelmed from the terrible explosion. Most of the day’s deaths were concentrated in these moments.
They also counted each other between 2000 and 3000 injuredespecially among the workers of the nearby industrial area and among the children during those hours at schoolinjured by debris and glass caused by the explosions.
Fragments of the ship or parts of the cargo, including drilling material weighing up to 1200 kg, were also found 4 km from the port, which was practically razed to the ground. A following one wave of about 4 meters submerged the surrounding area and the nearby Monsanto plant, moving a supply ship 60 meters onto land.
The second explosion and the damage in the surrounding area
The explosion of the Grancamp caused heavy damage the surrounding shipsincluding the High Flyer: This ship was also loading large quantities of nitrate (961 tons, plus 2000 tons of sulfur), and it was stopped for maintenance work to the turbines, making it impossible to maneuver without the help of tugboats.
Also the load of the High Flyer caught fire: the ship was uprooted from its mooring colliding with another. The anchor fell on the backdrop and stopped the ship on the spot: i tugs arrived from Galveston they attempted several times to move it, finally managing to free it but, during the move towards the port exit, the second explosion at 1:12 a.m. on April 17.
Since the entire area had been evacuated, losses were much more limited and incredibly the tug’s crew was only injured.
The surrounding industrial area suffered huge damagewhile in the residential area one third of the 1519 buildings were declared not habitable (to be demolished or at least in need of extensive work) and many others required minor work, mainly roof or window repairs: the estimated damage bill was at least $33 million at the time (about 460 million currentlyconsidering inflation).
The dangers of ammonium nitrate
The ammonium nitrate (NH4NO3) is one of the first and most important synthetic fertilizers developed by man, due to its ability to release nitrogen (35% by weight) into the soil and promote plant growth. At the same time, it is an oxidizing compound and therefore used together with explosive compounds in the war industry. Under normal conditions it is relatively stable and difficult to burn, resistant to heat or friction sources. Possible anti-humidity treatments with waxes or paraffins, combined with packaging materials like paper bags, they can however encourage flammability.
At temperatures above 170 °Cammonium nitrate undergoes decomposition releasing nitrogen gases (NO2N2O, N2OR4) from the characteristic reddish colour and catching fire it reaches temperatures up to 1500 °C (2700 F).
Unfortunately, an explosion of this type also occurred in Beirut on 4 August 2020.
Disaster management and analysis of the incident
There relief managementwith medical and firefighting personnel quickly arriving from nearby cities, was commendable despite the lack of an emergency plan. However, studies following the event highlighted serious security shortcomings of the port area and inabsence of information for the storage and handling of ammonium nitrate cargoes: i port workers were not aware of the dangerousness of the goodsthe local authorities were not notified of the cargo movement and no one notified the firefighting personnel who intervened in the morning.
These measures, now part of the normal operation in many nations, they could have saved many lives: even today, however, bad practices and carelessness can lead to similar tragedies being repeated.
