Industrial explosives

[Feo Takahari]

One of the characters in my current story is an ecoterrorist, and he needs to destroy an assembly line at a factory. I'm thinking of having him use stolen industrial explosives, but this raises several questions that I'm having a hard time answering:

* What sort of explosives could he feasibly steal? (I don't need brand names, or specifics of where he'd steal them from, just a general idea of the type.)
* About what quantity and weight of these explosives would he need? Could he carry them in a backpack, would he need a wheelbarrow, or would he have to use a truck?
* Would he be able to set off these explosives without formal training, and without catching himself in the blast?

P.S.: If I just put the entirety of Mythic Scribes on a terrorist watchlist, I want you all to know that I'm sorry.

 

[Chilari]

What time period are we looking at here? Present day? 1950s? 1870s?

 

[CupofJoe]

And how long/big is the assembly line? Are we talking a building or just a room or two within one. That will affect your options...

 

[Sheilawisz]

Some type of plastic explosive would be the easiest to steal and to make a small bomb with it, even if the character in question is not really a super expert in explosives =)

I know that plastic explosives are really strong, and a bomb the size of an apple or a little larger would be powerful enough to blow up that assembly line at a factory or maybe even an entire house- However, I am no expert about these things... Maybe to actually make a plastic explosives bomb and safely detonate it would be impossible for a person with little knowledge.

Another option would be to use nitroglycerin, which was commonly used as an industrial explosive and is very powerful as well...

 

[Feo Takahari]

What time period are we looking at here? Present day? 1950s? 1870s?

Present day.

And how long/big is the assembly line? Are we talking a building or just a room or two within one. That will affect your options...

I'm thinking of it as a relatively small factory, so probably closer to a room or two.

 

[Ravana]

* What sort of explosives could he feasibly steal? (I don't need brand names, or specifics of where he'd steal them from, just a general idea of the type.)
* About what quantity and weight of these explosives would he need? Could he carry them in a backpack, would he need a wheelbarrow, or would he have to use a truck?
* Would he be able to set off these explosives without formal training, and without catching himself in the blast?

Plastic explosives are not among the easiest to steal—and, conversely, are very easy to trace: all plastic explosives manufactured for the past several decades contain taggant chemicals for just this reason. Good old-fashioned dynamite would be far easier to get ahold of… though he'd need more of it.

However… a great many explosives can be home-brewed with minimal difficulty, though not with minimal safety. Nitroglycerin is easy to make… it's also fantastically unstable and hazardous: it can be set off accidentally by heat or even a good bump. (Medical nitro is also available, usually as glyceryl trinitrate to prevent people from realizing what it is; I suspect this is generally mixed with something to make it less volatile, but I'm not sure.) Turning the nitro into gelignite—the original plastic explosive—is not too difficult; once this is made, the compound is quite stable… stable enough to require an actual detonator to set it off. Dynamite can also be made from nitro; it too requires a detonator of some sort. Trinitrotoluene (TNT) can be home-brewed as well; as with dynamite, it is far more widespread than commercial plastic explosives, so would be easier to steal.; again, a detonator is needed to trigger it.

The problem with home-brews is that if you get the mixes slightly wrong, the stuff won't go off, or won't have the desired power… or will still be unstable and go off when you don't it to. Which is why most people would rather steal dynamite from a mining business than try to make their own.

Another problem is that all of the above require access to high-concentration sulfuric and nitric acids… more concentrated than is available "over the counter." Access to these is generally restricted and tracked by the government—in part to keep people from home-brewing explosives, in addition to the more obvious hazards of handling the stuff at all.

Given that common explosives do require detonators—blasting caps being the usual—these would have similar availability in terms of theft. In some cases, percussion caps may be adequate, and these are available to firearms hobbyists who like to hand-load their own ammo—or, to reverse it, can be removed from over-the-counter ammo. What I'm not certain of is whether a percussion cap stripped from, say, a rifle round, would be large enough to provide the appropriate shock to trigger explosives (but see below).

Gunpowder—or, rather, cordite and its many cousins, which have long since replaced black powder—is always an option, and here it doesn't need to be homemade… as long as you're willing to sit there emptying shotgun shells until you have as much as you need. However, it is also hazardous to work with, if not as much so as nitro, and the more you pile in one place the more dangerous it becomes. (Avoid sparks.) For that matter, you can buy the stuff directly—as mentioned, there are those who like to load their own cartridges—though this would leave a clearer trail. The biggest disadvantage is that it is not efficient: you know the term "high explosive," but may never have thought through to the obvious companion term "low explosive"—which this is. It would take a whole lot of it to make a bomb of consequence. Your character would do just as well making a fertilizer bomb… that is, something too big to easily transport.

Another option is thermite: not an explosive, it burns at such a high temperature that it readily damages metal. It's widely available for commercial use—it's used to weld railroad track, for example. Better still, it doesn't require any special detonator, just something hot enough to get it started—a sparkler can be enough, though for reliable ignition you'd be better served by magnesium strips… or at least a road flare. It can be homemade from powdered aluminum and iron or copper oxide, if you get the proportions right, and if you get it correctly packed or mixed with a binder so that it stays where you want it and doesn't just scatter with the first spark. Fail, and it's just powdered metal.

As for amounts: it depends on how much damage he actually needs to do. It isn't necessary to destroy a building to put an assembly line out of commission: all he'd need to destroy are parts of it. If those parts are critical enough and/or difficult to replace, a little boom (or burn) can go a long way. It would be more efficient to plant four sticks of dynamite in four critical places than to carry in a backpack full and set it off all in one location. Of course, that requires making four bombs rather than one.…

Shaped charges (plastic explosive, formable thermite) are more efficient than simple bombs: with the latter, the force expands radially, and only a small amount will damage the thing you most want it to—especially if you're trying to destroy industrial metal fixtures. Unless what you want is to bring down the whole building on top of the assembly line; this might not do a lot of damage to the critical pieces, but digging them out and dusting them off properly will certainly be time-consuming.

The setting off part… usually requires some skill. Doing it in such a way that you're not caught in the explosion can be tricky as well. It's not as easy as attaching a clock to a bomb, as movies make it appear. First of all, the clock isn't able to send a signal by itself: it needs to be attached to a battery in such a way that when a certain time is reached, it causes the battery to send a charge to the blasting cap… or caps, if you're trying to place multiple bombs. The wiring can be looked up easily enough, though: it would be no different from wiring a timer for any other purpose. Burning fuses cannot be used to detonate most of the above compounds directly (they'll ignite gunpowder); these days, burning fuses are used to trigger detonators, which means you'd still need one of these anyway. There are other options: one, the "pencil detonator," was developed for espionage/sabotage use during WWII, and uses acid eating through a measured amount of wire as a timer: when the acid eats through the wire, it releases a striker which hits a percussion cap. Which means you still need a percussion cap… and since these detonators were manufactured as military devices, the cap might be larger than that used in common ammo.

The worst thing that can happen is your bomb doesn't go off when you expect it to. Do you risk going back to check the setup, see if the timing mechanism failed to trigger the explosives, if the detonator wasn't set just right? Do you try to reset things for a second attempt? This is almost universally regarded as a "bad idea": your chances of accidentally completing whatever circuit or step failed—or of simply discovering your trigger was, oh, that much slower than you thought it would be—are far greater than your chances of getting it reset.

P.S.: If I just put the entirety of Mythic Scribes on a terrorist watchlist, I want you all to know that I'm sorry.

Probably. But I'm used to it.

 

[Feo Takahari]

From this and other sites, thermite molded with clay sounds like the most promising substance--he can place it at various points, and then set it off with flares. Anything else I should know about it to avoid inaccuracies?

 

[Sheilawisz]

Thermite would do the job just fine, but for a character that is not really trained with explosives then maybe a simple gunpowder bomb would be the best option...

Gunpowder is not as powerful as the high velocity explosives (TNT, Plastic explosives and others) but its destructive power is not to be underestimated: a Pipe bomb full of gunpowder would destroy the Assembly line for sure, likely also killing all the workers that are unlucky to be nearby.

It takes just a fuse to detonate it, and it's perhaps the easiest explosive to make without a lab and chemical ingredients.

 

[Ravana]

Actually, a pipe bomb loaded with gunpowder would probably do no damage to the assembly line whatsoever: pipe bombs are anti-personnel explosives, essentially impromptu hand grenades. Most of the explosive force is taken up in shattering the pipe itself—which is the point of putting the explosive in a pipe in the first place; the "damage" is done by the fragments. It would have to be firmly wedged into a critical area to deform metals, which is most of what any assembly line is made of (and most of that will be steel). Placed next to electronics it would do at least some damage, though it would really need to be placed inside control panel covers to do much more than score the surface or break a few bits of glass… and most covers don't leave enough space for one to fit, though one could leave the cover open and tape the device to the electronics if it's to go off long before any chance of discovery. In any case, a stick of dynamite has much greater explosive force, and is smaller and lighter to boot.

That is, unless you're talking a sewer-pipe bomb.…

The physics of pipe bombs leads to a more general point: where does the force go? If an explosive is placed in the open, it goes in all directions at once—and will proceed along the paths of least resistance. The part of the explosion that encounters solid objects will largely be deflected away by them; they really only begin to do structural damage when there is no place for the force to be deflected away to, i.e. when the pressure of the explosion is so great that the entire space is filled by it while still expanding. At which point it will still follow the path of least resistance: weaker materials will give way before stronger ones do.

This is why artillery ammunition falls into two categories, high explosive (HE) and armor piercing (AP). HE ammo is all but useless against armored vehicles (tanks): even if a direct hit is scored, there's all this air surrounding the target which the explosive force finds easier to expand into than the tank's armor. Most AP ammo takes advantage of some form of shaped charge: it doesn't "explode" all at once, but instead burns front-to-back (albeit very rapidly), thereby forcing the expanding gases, usually supplemented by a quick-melting metal, forward into the armor.

The upshot for the bomber is that, if the assembly line is made of metal but the building is not—which it generally won't be, of course—a bomb placed in open space will bring the building down before causing much damage to the line itself. (And even more likely will blow the roof off before damaging the walls.) Which is why placement is critical. If the bomb is placed in a confined space, that much more of the explosion will be forced against whatever he's trying to damage.

One excellent historical example, on which there is abundant documentation, is Claus von Stauffenberg's attempt to assassinate Hitler. A one-kilo plastic explosive bomb in a briefcase (using a pencil detonator, by the way) was detonated inside an above-ground concrete bunker meeting room, within which were 25 people. From the outside, it "looked" to von Stauffenberg like no one could have survived the blast. In fact, only four of those 25 were killed. The majority were shielded to greater or lesser extent by a heavy wooden table with wide, solid legs, and most of the blast exited through the windows… visually impressive from the outside, but not at all the desired results within. Had the bomb not been moved just prior to detonation, it would have been to the inside of those wooden legs, which along with the tabletop would have directed the blast against the bulk of the people standing around the table, in all likelihood killing most or all of them.

That's a kilo of plastic explosives inside a relatively small reinforced concrete room, with nothing else other than wood to damage (or deflect the damage). If you want to cause meaningful damage to tooled metals in a vastly larger space, you're going to need a larger bomb than one person could easily carry… or you're going to need to place your charge(s) strategically.

Given the way Feo was talking about the bomber, I was guessing he meant it to be planted and go off when no one was there. Ecoterrorists are often funny about killing. Not always, but often. In general, most activist (versus genuine terrorist) bombers don't want people hurt, as that tends to generate antipathy rather than sympathy to their cause—which is one of the reasons bomb threats are often called it once an explosive has been planted: it allows the chance to evacuate the area and leave only property damage. (That, plus it's easier to take the credit if you're the only one who's mentioned it ahead of the explosion; dozens of crackpots and/or competitor causes always call in after any explosion.)

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The thermite would be a reasonable choice. It would not be too difficult to obtain, and is not too difficult to work with. The magnesium strips that are the trigger-of-choice would probably be even easier to obtain, so he may not have to bother with the flares, unless you want to give it a "homey/amateur" feel. One further advantage of thermite: if he does not run the risk of being detected as soon as it goes off (by a night watchman or such), he wouldn't even need to leave the area; he can sit there, set one charge, step back a few feet, watch it cook off and move on to another… no chances of failed charges. This might stretch credulity somewhat, depending on what kind of plant we're talking about—and it may or may not trigger fire-suppression systems, depending on what sensors they use; if it does, it will also trigger an alarm—but it's a possibility.

 

[ascanius]

Anarchist cookbook by; the Jolly Rodger, not that piece of garbage that is published now under the same tittle.
Terrorist handbook by; unknown.