The power of water expansion and contracsion

[leaddog]

I Built a side arm for my neighbor 2 years ago. It was made of 1in copper inside and 2in copper outside. He called me this season and said that when he started up his boiler it started to over flow. I determined that the sidearm was leaking inside and took it apart I couldn't believe what I found and it took me a long time to figure out what happened.
The 1in copper tube was collapsed and split at the crease for about 5in.
He remodeled his house this summer and turned the water heater on and off several times. It's an elect 50 gal heater and during the summer he used elect and during the winter turned the elect off and used the sidearm. When he turned it off during the remodeling he turned off the supply and exit valves off. This must have created a huge vacuum when it cooled off each time and collapsed 1in tube.
I would never believed you could collapse a 1in copper tube like that but because I built it I know the tube wasn't damaged when I put it together. Now if he turns it off he will only turn it off at one place so when it cools down it can use the pump tank to take up the vacuum.
Thought I would throw this out there so others can realize the power of expansion and contraction

 

[leaddog]

Here is a Pic

 

[leaddog]

An other pic

 

[Buzz Saw]

That's impressive. I would of never guessed that would happen.

Sent from my SM-G900V using Tapatalk

 

[leaddog]

Yes going from 150* to 70* in a completely closed system would cause a vacuum but I would have never thought that much. I'm surprised the tank didn't collapsed. Has any one else here seen anything like this or was something else in play?
leaddog

 

[maple1]

So, when the collapse happened - boiler water would have been sucked into the DHW tank? That copper must have been the weak point - then once it collapsed & opened up the boiler water introduced would have alleviated the vac pressure which prevented tank damage.

Thinking out loud...

 

[DoubleB]

What was the pressure inside the 2" copper pipe? Even with a vacuum inside the 1" pipe, I would imagine it would take additional external pressure for the collapse.

 

[leaddog]

What was the pressure inside the 2" copper pipe? Even with a vacuum inside the 1" pipe, I would imagine it would take additional external pressure for the collapse.

The 2in pipe was on the open outside boiler side so no pressure.

 

[leaddog]

So, when the collapse happened - boiler water would have been sucked into the DHW tank? That copper must have been the weak point - then once it collapsed & opened up the boiler water introduced would have alleviated the vac pressure which prevented tank damage.

Thinking out loud...

Yes I'm sure that is what happened but I would have thought it would take more vacuum to collapse a 1in pipe than a large dia. tank and I never thought it possible to create that much. Putting boiler water into the DHW wasn't a good thing either but it would have been a small amount and because of the remodel a lot of water was flushed and then being heated to over 150* should have been safe.
Every one worries about expansion and I never hear any worries about vacuum
leaddog

 

[warno]

Just throwing this out there, was it possibly closed off right after sweating together? because that much heat cooling down I could see pulling a vacuum to do the trick. I think things people forget is that after heating copper during sweating, it anneals (softens) it like crazy also.

 

[STIHLY DAN]

I will bet money it is not cooling vac, but it had been drained during that time with the valves closed. Or attempted to be drained. Many tanks out there have coils in them and go cold. like when power goes out. This coil splitting probably saved the tank from collapsing.

 

[leaddog]

Just throwing this out there, was it possibly closed off right after sweating together? because that much heat cooling down I could see pulling a vacuum to do the trick. I think things people forget is that after heating copper during sweating, it anneals (softens) it like crazy also.

No the unit was made and installed later and was open when sweated
leaddog

 

[leaddog]

I will bet money it is not cooling vac, but it had been drained during that time with the valves closed. Or attempted to be drained. Many tanks out there have coils in them and go cold. like when power goes out. This coil splitting probably saved the tank from collapsing.

I'm sure the tank might have been drained sometime during the remodel but that would have been done with the drain valve and like with a bottle of water if you tip over it will drain, stop, gurgle air, drain etc. It could never pull that much vac. Tip a 5 gal plastic water container over and it will take a while but you won't collapse it. I'm not sure the psi that a 1in copper pipe will hold but think the burst point is over 600psi
leaddog

 

[STIHLY DAN]

Tanks that get drained from the drain valve without a faucet open collapse all the time. Thats why most places have a code that a vac breaker must be installed.

 

[leaddog]

Tanks that get drained from the drain valve without a faucet open collapse all the time. Thats why most places have a code that a vac breaker must be installed.

Thanks, I never thought that. It's good to learn something new

 

[whosthat]

I work with alot of tanks at my job, ive seen a 35000 gal tank implode from vac. that being said you cant create enough vac on a tank draining it without a vac breaker, it will simply drain slowly as air will be getting sucked up the drain to equalize the pressure. only hot tanks made of plastic will deform this way. PUMPing out a tank without a vac breaker is a diff story though.

Btw we imploded the tank at work by cooling it rapidly by mistake and it had a 12inch vav breaker but still crumpled like a soda can

 

[mustash29]

Mythbusters - rail car implosion.

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Controlled Demonstration of a Tank Trailer Vacuum Collapse by Wabash National.

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