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Harry K

wrote:
OK, this thread is as attractive to trolls as any, but for serious
discussion- what is the actual mechanism of a pipe cracking/bursting
due to the water freezing?

OK, we all know water expands when frozen, and this is the root of it,
but beyond that...
I'll sketch out what I believe the mechanism is using a series of
examples.

make a big "U" out of a copper pipe, like this:

| |
| |
-----------------------------------

fill that puppy with water. Freeze under the following conditions:

1) leave ends open, start freezing at middle, freeze whole pipe working
out towards the ends.
predicted outcome- no burst pipe

2) Leave right-hand end open, seal left-hand end. Freeze from left to
right
predicted outcome- no burst pipe

3) Leave right-hand end open, seal left-hand end. Freeze from right to
left
predicted outcome- burst pipe

4) leave both ends open. Freeze from ends towards middle.
Predicted outcome- burst pipe.

Further prediction: the point where the pipe cracks/bursts will be at a
point where there is water in the pipe, not ice.

Discuss.

Dave

As freezing conditions a not normally a 'point source' problem, it is
most likely that it will start to freeze over several feet of pipe.
Even with both ends open it is stillpossible to wind up with a broken
pipe. The interior of pipe is rough (galv) and you can get one or more
'ice plugs' and cause a burst between them.

Haryr K