Havererade fartyget Ruby med 27.000 ton ryskt ammoniumnitrat ombord söker nödhamn

Pure ammonium nitrate (AN) is actually very hard to make detonate! You really, really have to work at it to get it to explode, and then it is only about 40% as powerful as TNT. There have been several notable explosions from it, but invariably, it has only been after the material has been exposed to great heat for extended periods, like in Beirut and Texas City, or has had an explosive initiator, like the one in Oppau Germany.

Just to illustrate these things, consider first the Beirut explosion. The material was stored under a shed for several years in Beirut’s hot climate. Then, a welder, it was reported, ignited a large stash of fireworks stored next to it. The fireworks, not surprisingly, eventually ignited the AN. The AN began to decompose giving off an orange gas of nitric oxide. For those knowledgeable about AN, that orange smoke is a clue to go somewhere else VERY fast, or you will be unceremoniously sent elsewhere VERY fast. (In the first case, the various attachments will remain with the torso, whilst in the second case, the various attachments like arms, legs, perhaps a head, will be detached and left for others to (hopefully) recover.) Video of the fire in Beirut clearly shows the fire accelerating in violence in the minutes leading up to the explosion.

The Texas City explosion in 1947 resulted when a shipload of AN caught fire and instead of trying to flood the hold with water, the ship’s crew put steam into the hold. Now, for an ordinary fire, that would smother it with no problem, but when they put steam in the hold, they heated the AN making it more reactive. Eventually, the AN had received enough of an insult and blew up, blasting the ship to pieces and killing dozens of people.

The explosion in Oppau, Germany in (IIRC) 1923 occurred when a HUGE pile of AN mixed with ammonium sulfate was dynamited to break it up. Although this had been done dozens, if not hundreds of times before, this time was one time too many. The explosion demolished the town and left a big crater in the center of town.

So the first order of business is to recognize the AN is an explosive and treat it as such. Although it is very insensitive, and not very powerful as explosives go, it is still a material that has to be treated with respect. Neither the responders in Oppau nor Texas City appreciated the material they were dealing with was that dangerous. The Port Authorities in Beirut, on the other hand, clearly did know of its explosive properties, but were unable for legal and financial reasons to do anything about it. They had struggled for several years to get rid of it but always ran into problems.

Second, a water spray will cool the material and keep it from decomposing. Ammonium nitrate doesn’t really burn in the usual sense of the word. It decomposes and self-burns with oxidation and reduction taking place on the molecular level. In this process, considerable heat is released. if the heat cannot escape fast enough, the reaction continues to get hotter and hotter until there is in the terms of the explosives world, a DDT. That is, a Deflagration Detonation Transition. Spraying water on it will keep it cool enough to prevent such unpleasantness.

Third, limit the amount of AN in storage the smallest amount possible. A small amount won’t get hot enough to DDT since the decomposition will run out of material before that point is reached.

Forth, store the AN in a sprinklered area. If the material does get ignited, the sprinklers will keep it cool enough that it won’t detonate.

Fifth, store the material for the shortest possible time. The Beirut material had been sitting around for a couple of YEARS! Unless a proper bunker is available, the material should be removed as soon as possible. Using a port warehouse for storage is NOT a very good idea.