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
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
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,
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.
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
Very interesting. Perhaps only a coincidence, but the two pipes I had that
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.
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
Point is, freeze bursting may be totally predictable and scientific and
explainable, but from my observations, it burst in some pretty weird places.
If one had the local tube thickness, weld strength/lack, etc., etc.,
etc., ... as well as the water infill pattern it would undoubtedly make
more sense. Simply looking w/o analyzing all the factors would make the
cause/effect relationship difficult to pick out, no question...
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
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
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