It is not the ice that causes pipe bursting
Shane Turcott
Principal Metallurgist @ Steel Image | P.Eng., M.A.Sc Materials Engineering #reliability #failureanalysis #steel
Water freezing within pipes is responsible for many expensive failures. But it’s not the expansion of the solidified ice itself that causes rupture, it’s the unfrozen water that is the killer.
When water freezes into ice, there is a 9% volume expansion. Copper and steel pipes typically have the ductility to handle this slow volume expansion. But if two sites along a pipe freeze, or freezing begins near a dead leg, the water trapped in between becomes compressed and pressurized. As more freezing occurs, the water pressure increases until it causes ruptures.
To demonstrate this for a failure analysis project, we replicated freezing failure on some pipe.
After welding thick plates onto the ends of an ASTM A106 carbon steel pipe, the pipe was filled almost to the top with water, plugged and put into a freezer. Because there was a bit of air left at the top of the pipe, the water froze from the bottom up and no encapsulated water pocket formed. Without entrapped/pressurized water, the steel pipe expanded a little from the water-to-ice volume expansion but didn’t rupture. The pipe had enough ductility to accommodate the water volume expansion.
The pipe did not fair as well when completely filled with water. Before all the water had frozen, the pipe ruptured. Unfrozen water had burst out from the rupture and froze on the outside of the pipe. The water pressure had been high enough to spray the side and ceiling of our freezer.
After cutting open the pipe, it could be seen that ice had formed all around the internal pipe cavity, pressurizing the remaining, unfrozen water. It was the pressurized water that had caused pipe rupture, allowing the water to escape.
Pipe failures often occur during cold snaps yet leaking doesn’t happen until later when it warms up. You can see why. The ice had sufficiently blocked the pipe to pressurize the entrapped water. After rupture, the ice blockage prevents significant leaking from occurring.
Where all Canadians look forward to the coming of spring, their insurance companies who pay for water damage do not. It’s because only until it warms up that the ice seal begins to melt and the burst pipes really begin to leak. Every spring thaw, numerous pipes that actually burst in the winter cause hundreds of millions of dollars in damage in infrastructure damage.
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4 年Great article, I work in the fire sprinkler industry we use compressed air in dry systems where the temperature is 40° or below sometimes the system is not drain properly and water is trapped in the system, what percentage of water needs to be trapped in a pipe that’s in the horizontal position so it has no room to expand which will cause to it break? This picture is a 6” sprinkler pipe with the cap off
Certified Quality Leader| Customer & Organization Vision- Centric| 14 yrs. Exp. in Oil& Gas/Renewable EPCM | Driving Excellence through Strategy, LEAN, Quality 4.0, CI ,Cross-Functional Collaboration & Motivational Fuel
5 年Interesting highlight Mr. Shane. As you said Mr. Shane, when water freezes to ice there is 9% volume expansion. What I believe is there will be always reduction in total volume, when the state of matter changes its phase from liquid to Ice or gas to liquid state, because of low energy of atom due to which the atomic mobility will get decreased, hence interatomic space will get decreased which will reduce it volume, please correct me if I am wrong?
Mechanical Engineer at Cool Innovations
5 年I'm unsure of the theory being put forward here.? I'm not saying you're wrong, but why do you suppose that unfrozen water would cause a pipe to burst, whereas ice wouldn't? The more intuitive approach would be that the reason that the pipe with an air pocket didn't burst is because the ice expanded into the air pocket (air being much more compressible than non-compressible water) instead of through the much tougher pipe.? Whereas with a full pipe, the freezing water had nowhere to go, and simply had to burst the pipe to expand. This would be true whether it froze bottom-up, or non-uniformly.
Director, Capital Construction & Realty Services - Halton Region
5 年Interesting read
Senior Reliability Engineer at Covalent Lithium Pty Ltd
5 年Is there any industry standards for freezing pipes