Looks like some bozo with a rifle decided to take some pot shots at a water tower in North Carolina:
Catawba County Sheriff’s deputy Major Coy Reid said the tower appears to have been shot three times with a high-powered rifle. He said authorities believe the shooting took place early Monday morning.
I would have thought water towers would be pretty resistant to small arms fire. In addition to the shape usually being rather roundish, I would have imagined the metal would need to be thick enough just to contain the water that it could deflect a hit from most projectiles.
Tests I have done show that a 30.06 with ordinary hunting ammo can penetrate on the order of 0.5 inches of mild steel.
The water pressure in those tanks is very low. At the surface of the water the pressure is the same as the atmospheric pressure. For each foot of depth into the water the pressure increases by about 0.433 PSI. So if the tower is 50 feet tall and is full of water then the maximum pressure is only about 22 PSI. The tires on your car easily contain over 30 PSI. Hence the material of water tanks can be as easily penetrated by rifle fire as your car tires.
My guess is that with a square-on hit most pistol rounds would penetrate the water towers.
All of this is contrary to popular belief. One nut-case (for other reasons) by the name of Newton Brown who held the job title of “Government Scientist” told me he thought a water tower would dramatically explode if hit by just one bullet. Even after I explained the low pressure in the tanks and the results would be no different than drilling a hole in the tank I don’t think he really believed me. But then, I guess there is a reason why he works for the government instead of holding a real job.
I suspect the person who shot the water tower thought it would explode as well.
Not very long after 9-11-01, somebody also put a bullet through the Alaskan oil pipeline, resulting in about a quarter of a million gallons spilled oil and a lengthy, expensive repair/cleanup process. It, too, is not bulletproof. (Although, IIRC, the ultimate cause in that event had more to do with alcohol than malice.)
Most folks have no notion of just how much metal a high-power rifle can punch through; it takes a decent amount of hard steel to stop a .30-06 or a .308, and most things just aren’t built out of armor plate. Ordinary construction steel is mild, not hard, and seldom even half an inch thick. Punching through it with any rifle larger than a varminter (or even with a varminter, for that matter) can be frighteningly simple.
On the upside, most everyday objects do not explode when shot through, either. It’s hard to imagine the disconnect from reality that would lead anyone to believe a water tower might do so!
There could be different thicknesses of steel in the tower (depending on height and whatnot). It seems to depend on the design (over half an inch near the bottom, below half an inch near the top).
Never thought about water tanks, but I always wondered how long it would be till some nut case started taking pot shots (with tracers) at those giant gasoline tank farms.
As long as the wacko with tracers kits the tank “below the waterline” all that would happen is the retaining dike gets a workout throught the hole. if it hits fumes well-mixed with oxidizer…
“Well-mixed” is probably a little more “interesting” than most people realize. Ordinary gasoline will not ignite unless the fuel/air ratio is between 1.20% and 7.6%. For #2 diesel it is 0.6% to 6.0%. Methyl alcohol is much more tolerant with a range of 6% to 36%. Nitromethane has an incredible range of 7.3% to 63%.
But then there is the Flash Point to consider too. The Flash Point is the temperature below which not enough fuel will even go into the air. The Flash Point for gasoline is -45F. For #2 diesel its 126F. For methyl alcohol it is 52F. For nitromethane it is 95F.
Beyond that is the actual ignition temperature. But I’m probably starting to bore people with details already. As I have said before (http://blog.joehuffman.org/2007/09/05/EnoughColumnsOnTheSpreadsheet.aspx) there are lots of columns on my spreadsheet.
From the time I purchased my first gun in ’94 until the conclusion of “Project Fireball” (http://www.boomershoot.org/general/fireball.htm) I spent a lot of time trying to make bullet initiated fireballs like what you see on TV and the movies. It was not just surprisingly difficult, it was embarrassingly difficult. I have it figured out now and pretty much can do it on demand, but it’s not nearly as straightforward as most people believe.