Why hasn't my copper pipe burst after feezing?

[jack]

I have had burst pipes, so I know it happens.

Just as an experiment I took 8" of 1/2" copper and capped one end. I filled it with cold water and stuck it in my freezer. After 30 minutes it was somewhat frozen, and solid after an hour. But 4 hours later it hasn't burst.

So, why do some pipes burst, but not this one? The ice expanded out the top, so it definitely expanded. Perhaps it has to be physically prevented from expanding with a right angle piece at the top?

(My cottage has exposed copper pipes and no heat, and I try to avoid draining them until necessary. When the temperature gets down there I get antsy. I am experimenting to get a better idea of just what the danger really is.)

[Edwin Pawlowski]

There's your answer. Solder a valve on one end, fill, close valve, then freeze

[Tony Hwang]

Hi, What is lowest typical temp. in winter at your cabin?

[Wayne Boatwright]

On Sat 04 Oct 2008 09:35:32p, jack told us...

It needed to be capped on both ends, or capped on one end and a closed valve on the other end. Under those conditions, when frozen it would have burst.

[jack]

Typically about 10, though it can get down to 0 some years.

[Frank]

May take several freeze/thaw cycles to stretch to break limit.

[Blattus Slafaly]

Cap both ends and try it again.

[Richard Evans]

FWIW, in 1984 I moved to West Palm Beach, FL. The incoming water line was completely exposed for about three feet where it came up the outside of the house. Wouldnt'cha know it, my first night there they had a hard freeze, temp down to 22 degrees. The exposed line froze, but did not break. Presumably, that would count as having both ends capped.

[Big Al]

Presumably not:) Water can go back into the main.

Al

[jack]

Sealing the top doesn't seem right. The one time I had broken pipes, they were drained, but there was some residue left in low spots. They had plenty of room to expand into.

I thought a better test would be to put a right angle bend on the pipe; then fill it and let it freeze. The right angle would reduce the ice's ability to expand, and would be pretty much like real plumbing.

4 hours at zero and it didn't do anything but freeze. It didn't even swell.

Apparently my simulation is deficient. Maybe the bottom of the L has to be much longer?

[dpb]

Was the broken/frozen piping in the house L or M? The thin wall stuff is much more likely to burst although heavier isn't a guarantee it won't.

Clearly you must have had sufficient volume in the particular places and a restriction sufficient for there not to be the expansion room or it wouldn't have burst then, either.

There's also a difference in the internal roughness of new vs old pipe that an ice column might slide a little on new pipe where the scale and corrosion on used won't as easily. There does have to be a restriction, though.

However, I'd guess the biggest problem in the simulation is that you're unable to actually completely fill the volume and so there's sufficient air volume available to compress to accomodate the phase expansion. In a plumbing system, there is essentially no air volume in a pipe--that's harder to do w/o the continual feed.

--

[Edwin Pawlowski]

If you don't seal the water in some manner it will move to the outside and not exert pressure on the tubing walls. The water in low spots of your pipe is a different scenario of a test pipe in the freezer. At some point the water at the ends freezes and makes a plug. Later the center freezes and exerts pressure in all direction but since the shallow water at the ends froze first, it can burst the tubing.

You may find this interesting too. Hot water pipes can freeze before cold water pipes.

[jack]

burst were both hot water pipes.

It is also somewhat reassuring that 32 degrees isn't the magic number; that it must be rather colder to get burst pipes.

Thanks.

[mm]

Yeah, I think the pressure of expanding ice is greater than the water pressure in the main.

And I can prove it.

The pressure of expanding ice is greater than the strength of copper water pipes, or the pipes would not burst when the water freezes.

The strength of the copper water pipes is greater than the water pressure in the main, or the normal water pressure would cause the water pipes to burst.

So the pressure of expanding ice is greater than the pressure in the main.

[Mark]

Try a longer piece of pipe, make a zig-zag out of a couple lengths and some elbows and I'll bet you'll find that it will burst somewhere along the length once the open end freezes solid.

[hallerb]

ewhere along the

I had my main freeze once in my basement when a window fell open for unkniown reasons.

surprisingly it did no harm, i replaced the windows latch.

I have read that all new faucets are designed to leak under the very high pressures from frozen lines. the drip that results saves lines from splitting. faucets dont leak till 200 PSI or something like that

[MLD]

Feeze the open end first if you can and then let the rest freeeze and see what happens MLD

>

[Bob F]

I freeze soda bottles without rupturing them just be leaving an air space at the top. Without air in the pipe (both ends sealed) it will probably rupture or stretch.

[SteveB]

As an aside (something probably totally irrelevant and not to do with this discussion), I have seen and fixed LOTS of spindles in ornamental metal railings and fences that were burst from freezing. When constructed, the ends were not welded totally shut, and water infiltrated from somewhere. It is amazing to look at these burst tubes, as they are burst in all places. At the top, the bottom, in the middle, everywhere. One would think that the water would migrate to the low point, and freeze there. Yet there are obvious bursts in the middle of six foot sections. Maybe that's just the point at which it started freezing after filling the tube half full. And this was in the temperate climate of Las Vegas, and it's not that cold there.

Point is, freeze bursting may be totally predictable and scientific and explainable, but from my observations, it burst in some pretty weird places.

Steve

[SteveB]

Has Mythbusters ever done the experiment on which freezes first, warm water or cold water?

Steve