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Frozen copper water line shows freeze stresses (C) Daniel FriedmanMechanics & Forces of Freezing Water
Effects of ice & freezing water on buildings & pipes + the physics of freezing water

  • POST a QUESTION or COMMENT about the force of freezing water and ice expansion in or on buildings, plumbing systems, and in nature at rivers, lakes, ponds, streams

This article describes the expansive force of freezing water, or the force exerted by ice as it freezes and expands. The pressure exerted by freezing water depends on temperatures and other physical conditions, but it can be tremendous - enough to lift buildings, burst pipes & plumbing fixtures, and crush the hulls of ships trapped in ice.

What is the definition of the strength or force exerted by freezing water as it forms ice; how much expansion occurs as water freezes into ice & what are the effects on building plumbing systems; how can we predict where frozen pipes will burst?

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Freezing Mechanics - The Forces of Freezing Water

Frozen pipe burst damage pattern by joint separation (C) Daniel FriedmanHere we describe the typical effects of freezing water and ice on buildings and on or in building plumbing pipes & fixtures or in appliances such as water tanks or heating boilers.

We also discuss the physics of freezing water, explaining why it's the surface of water that freezes and why running water or water stirred by a bubbler freezes more-slowly or not at all.

Further below we will discuss freezing lakes, ponds and rivers, but first we'll take a look at freezing pipes.

Photo: this copper water pipe solder joint was simply pushed apart by the force of ice freezing in the pipe. Look closely and you can see that the original solder joint was not well-made. Below we show the more-usual way frozen pipes leak: by bursting.

[Click to enlarge any image]

Article Contents

Temperature at which pipes freeze vs when pipes will break

As we elaborate below, while water begins to crystallize into ice at 0°C (or 32°F), its expansive forces generally do not cause water pipes to burst until temperatures further fall to around 20°F or until temperatures remain below freezing for some protracted time period.

As water temperatures drop, water actually can become supercooled by a few degrees before it begins to actually crystallize into ice. That's because the expanding ice crystals give up latent heat, warming the surrounding water back up to 0°C.

When water freezes its volume, in the form of ice, increases by about 9% under atmospheric pressure.

If the melting point (or freezing point) is lowered by large increases in pressure, the increase in volume on freezing is even greater (for example 16.8% at -20°C (-4F).

Factors Affecting the Temperature at Which Water Pipes Will Freeze

The actual point at which water inside of water pipes freezes solid in a building is determined by a combination of factors including the following:

In general, 20°F (-6.67°C) is a practical number for the point at which water pipes are likely to freeze solid in a period during which temperatures dip below freezing overnight but don't remain there for days at a time.

Effect of Altitude, Atmospheric Pressure, or Water System Pressure on the Freezing Point of Water

Freezing point of water as affected by pressure - Wikipedia Commons 2018-01-20  https://en.wikipedia.org/wiki/Properties_of_water

[Click to enlarge any image]

The phase change chart for water shown above, from Wikipedia commons, adapted from Chaplin, plots changes in the point at which water freezes as a function of pressure. You can see that at atmospheric pressure the freezing point of water is 273.2°Kelvin or 0°C or 32°F. Pressure is mapped on the vertical axes of the chart.

The nearly-perfectly-vertical line between the blue area (solid or frozen water) and green area (liquid water) forms of water mapped against the vertical axes giving pressure show that freezing point of water changes only very slightly in response to very large changes in pressure.

Does Leaving a Faucet Open Prevent Freezing Pipes from Breaking?

We know that running water, by moving warmer water from some building locations to colder pipe locations that would otherwise freeze, we can defer or even prevent frozen water supply pipes.

Watch out: at DE-WINTERIZE a BUILDING we warn that while running water may prevent supply pipes from freezing you may cause the building drain to freeze, block and even burst.

Some building experts advice that when faced with freezing pipes or already-frozen water pipes we open the faucets, reasoning that if pipes are frozen you might reduce the chances of freeze-burst piping or reduce its extent by opening faucets.

Allowing even a small amount of water (from the un-frozen pipe sections) to drain out of the building supply piping might reduce some of the in-pipe pressure even if no water is flowing from the faucet. - Building Research Council (1996)

Really? While there is no question about the tremendous force of freezing water it appears to be less clear the direction in which those forces work in plumbing systems. Let's look at the force exerted on building pipes along the length of the pipe vs. across the diameter of the pipe as ice freezes.

Horizontal freezing water-forces (ice pressure) along piping lengths

Frozen pipe burst damage pattern by joint separation (C) Daniel Friedman

An exception to our horizontal split burst frozen pipe rule that describes what we have observed most often in buildings is the occasional separation of pipes at 90 degree elbow solder joint or even at a straight coupling or union (photo above).

In the photo above we show that clearly horizontal forces along the pipe pushed this pipe joint apart.

But look more closely at the solder joint and you will see that the original soldering job was poorly executed without proper cleaning and use of flux. The solder was not bonded to the copper and was not uniform in the joint - this was a weak point in the piping system so it's no surprise that the pipe failed here.

Lateral water freeze-forces (ice pressure) across building piping

Frozen pipe split pattern (C) Daniel FriedmanMore often, where I observed that pipe joint separation a plumbing elbow (a common freeze point in buildings), often the elbow of bronze rather than just thin-walled copper resisted splitting while nearby softer copper piping did not.

While expanding ice inside of water supply pipes may slightly increase pressure (as water is not compressible) our field experience and photos of frozen burst pipe such as the photographs at immediate left and again at below left suggest that most often frozen water pipes burst or split from the expanding ice pressure within a small section of pipe, creating first a bulge and then a split from forces across the diameter of the pipe rather than along its length.

It certainly appears from physical evidence that the water pipe shown in my photo bulged and then split by forces across the diameter of the pipe.

A rational view is that freezing water applies force in all directions rather uniformly. But the damage done by that force occurs where the force is confined.

But freezing water appears to be immediately confined more by the circumference of a pipe than along its length. Why might this be? Perhaps because the expansive force of ice increases as the temperature of the freeing water drops. A plug of ice forms in the pipe, the continues to expand as temperatures drop.

Why then might forces across the pipe be more confined than forces along the water pipe? We are not sure we not agree with one building expert who opines that the fill valve on toilets allows water, pushed along by freezing ice, to enter toilet tanks.

Really? Building water pressure varies over a range all the time for a variety of reasons (faucets open and shut, pumps starting and stopping) without ever pushing water through a closed toilet tank fill valve.

But there are building components that can absorb increasing water pressure:

What is the Expansive Force of Freezing Water?

Heaved ice fields on Lake Superior (C) Daniel Friedman at InspectApedia.copm 2019Expanding volume of ice:

Our photo and note below illustrate the tremendous force exerted as water, freezing to solid ice, expands by about 9%.

Freezing force of water:

as the water-ice temperature continues to drop to 0°F the forces involved range between 25,000 psi and can continue to reach 114,000 psi.

Compare freezing water pressure with burst pressure resistance of copper pipes

Burst resistance of copper water pipes:

the working pressure of 1-inch L-copper piping is 420 psi, and the actual burst pressure is around 2650 psi.

Similarly a 1-inch type M annealed copper pipe has a working pressure of 286 psi and a bust pressure for drawn M-copper pipe of 3865 psi.

Smaller-diameter pipes have greater burst pressure resistance. For example, half-inch Type M annealed copper tubing has a working pressure of 420 psi and drawn copper type M has a burst pressure of 6135 psi.

You can see that the freezing force of ice is between 60 and 270 times greater than the working pressure of a 1-inch L-copper water pipe, and between 10 and 43 times greater than the actual burst pressure of the same copper piping.

At BANGING BOOMING NOISE DIAGNOSIS & CURE we cite the force and the loud noises produced by freezing, fracturing water-ice.

Our photo above shows thick slabs of ice from frozen Lake Superior, Two Harbors, Minnesota, in February 2019. The tremendous forces of freezing ice (expanding by 9%) causes fractures and fissures in the ice field that combine with wind and wave action to produce a cacophony of bangs, booms, creaks, and other noises as great slabs of heave into the jumble shown in our image.

How much does water expand or contract as a function of temperature and how much does ice expand? Various sources give different expansion forces for freezing ice.

Depending on its state, freezing water (or ice as temperatures continue to drop past freezing (32°F towards 0 °F) can expand by as much as nine percent at a maximum force between about 25,000 and 114,000 psi.

Actually water reaches its maximum density above freezing, at about 4°C. It is the expansion of ice as it continues to freeze that explains why icebergs float - the iceberg displaces a volume of water that weighs more than the (expanded) ice itself. The tip of an iceberg seen above water usually represents about 8% of the iceberg's total volume.

Stated another way we can explain why ice is lighter than water by explaining its expansion as water changes from liquid to frozen state.

As ice freezes forming hexagonal crystals (comprised of two H molecules join with an O molecule at an angle of 104°) the water in this form takes up more space than liquid water.

But the crystals formed by freezing water take on varying forms (and affecting the pressures exerted by confined ice) as temperatures continue to fall. - Debenedetti (2003)

Before modern physicists and engineers began calculating the expansive force of freezing water, Florentine academics had measured the strength of freezing water by enclosing water in a brass globe of known thickness and strength, then allowing it to freeze. Those academics observed that a one-inch globe of water, when freezing, could exert a 27,000 pound force. - Platts (1880)

Frozen copper water line shows freeze stresses (C) Daniel FriedmanLuckily copper plumbing has some bending or flexing ability and does not break immediately. Copper water supply pipe strength varies by pipe type and wall thickness (K, L, or M copper) but break at around 3000 psi.

The thermal expansion of water is detailed

at THERMAL EXPANSION of HOT WATER.

Expanding ice forces are very strong when confined. Entire building movement caused by freezing and ice are discussed

at FOUNDATION DAMAGE by ICE LENSING

and at COLD WEATHER ROOF TROUBLE.

Watch out: while some experts advise leaving faucets open or dripping to avoid freezing pipes, this advice is risky if the building drains are exposed to freezing. In many areas the building main drain exits above the frost line and can be exposed to very cold conditions.

During normal plumbing use the surge of wastewater down the drain makes it past this cold spot without freezing. But a dripping faucet or running toilet, sending a small but continuous trickle of water down the drain can accumulate as ice until it expands, blocks the drain (leading to a sewage backup in the building) or until the drain line freezes and breaks.

On 2021-10-29 by inspectapedia.com.moderator (mod) - Build vs buy container capable of storing frozen water or keeping water from freezing by pressure?

HDPE waer containers that canwithstand freezing from SaganLife cited & discussed at Inspectapedia.com@Anonymous,

Thanks for a great question, that's an interesting idea.

The walls of any container, as they resist any force, including that of freezing water, in effect are exerting a "back pressure" - resistance = backpressure up to the point of bursting.

Shown above, an HDPE water storage container system than can withstand freezing, the Sagan Life Aquabrick(TM) provided by that California company.

From the article above on this page we have this key data:

When water freezes its volume, in the form of ice, increases by about 9% under atmospheric pressure.

If the melting point (or freezing point) is lowered by large increases in pressure, the increase in volume on freezing is even greater (for example 16.8% at -20°C (-4F).

It's true that the freeze-point of water increases slightly with pressure. But you need very large pressures to make any noticeable reduction in the freeze point of water.

What we didn't give in detail there were the effects on the freezing (or melting) point of water at very high pressures.

How to convert PSIG to PSIA

Remember that at sea level the true pressure or PSIA = 14.7 or 1 ATM (1 atmosphere). A typical water or tire pressure gauge that open to the atmosphere should be showing zero psig - it doesn't care that the atmosphere is pressing down on us at 14.7.

You'd need a Really Strong Container to Resist Freezing Forces, or ... maybe we have a better idea

Perhaps we've missed something essential in your question that would explain why we'd want to try to engineer a new container to withstand freezing water by some extra-mechanical means and as well as to exert 15,000 or more psia of pressure as well as to somehow defrost or melt ice without an external power or heat source.

In my OPINION the design cost and product cost of an inventing, building, and producing automagic defrosting system that melted ice by back pressure exceeds, by many orders of magnitude, other solutions for storing water under freezing conditions.

The pressure of freezing water is enormous - enough to crush concrete.

Why not store your water in flexible containers that are not filled to the top. Many plastics can tolerate the amount of expansion from freezing water.

There are many such containers already sold, starting with ice cube trays open at the top, and moving on Silicone containers (your best bet in our OPINION), and thence to Nalgene, polycarbonates, and other plastics, styrofoam-lined water containers, and similar containers used in water, food and medical applications.

Even a simple freezer type "zip-lok" storage bag can, if not over-filled, safely store potable water that's frozen solid.

ZipLoc freezer bags from SC Johnson at InspectApedia

The cost of these containers is trivial compared with the highly-engineered and un-proven idea of a container strong enough to avoid bursting under the pressure of freezing water and to exert back pressure thought to re-melt the water - in essence providing its own mechanical anti-freeze container.

The science of the ability of these containers to avoid bursting as their water freezes is simple: the container contains sufficient free volume to accommodate the expanding water as it freezes, or it is sufficiently-elastic to do so.

- Help in these water freezing temperatures vs. pressures was found at the Engineering ToolBox, www.engineeringtoolbox.com "Ice / Water - Melting Points at Higher Pressure" where those smarties provide an online calculator to compute the melting point of water at various pressures.

We did not find an engineering analysis that argued that the back-pressure of a container also would melt the ice it contained. Rather, at sufficient pressure the freezing point of water is lowered.

On 2021-10-29 by Anonymous - design a water bottle that exerts back pressure on water when it starts freezing?

We can use insulating bottles to store water under subzero temperature. However, we can’t provide this insulation for a long time.

We know that the freezing point of water decreases with increase in pressure.

This is because water expands when it freezes. When water is freezing, it will expand and exert a pressure on the inside body of a bottle.

Can we device a water bottle which can exert a back pressure on water when it starts freezing?

The back pressure created can re-melt the ice and thus avoid any freezing?

Thus, explain what are the stresses a bottle experience when water transforms to ice?

The Physics Freezing or Thawing Ice

Lake Superior frozen solid in February 2019, Two Harbors MN (C) Daniel Friedman at InspectApedia.comHere we describe several factors that affect the formation of ice on large bodies of water like Lake Superior as well as on ponds, rivers, and streams.

Photo: in February 2019 the combination of very cold temperatures and low wind velocity led to thick solid freezing of the surface of Lake Superior such that we could walk offshore.

In the distance is L.C. who grew up on the North Shore of Lake Superior and whose comments about the behavior of ice on the big lake are included below in italics.

Above: currents play a role in the thickness and other properties of ice on Lake Superior as well as in smaller rivers and stream that drain into the lake; on the lake itself we often see an open water “river" next to thin or thicker ice. - L.C.

Factors affecting when ice forms on a lake, pond, stream & river

Freezing surface of lake Superior, broken up and agitated by wind and waves (C) Daniel Friedman at InspectApedia.comOur photo shows thick chunks of ice floating on the surface of Lake Superior in two Harbors Minnesota in February, 2018.

Air temperatures were well below freezing. So why wasn't the lake surface frozen solid?

We've said that currents that move deeper, warmer water up towards the lake or pond or river surface can prevent ice formation (freezing) in that area.

But it's not just the movement of warmer water up towards the surface that lowers the freezing point of water.

A second effect that lowers the freeze-point of water in a lake, pond, or stream is agitation, or stirring movement of the water itself.

Strong wind kicks up waves that so agitate the surface of the big lake that the solid freeze of the lake surface does not occur until either there are days of little or no wind, or temperatures are considerably below zero.

At the site where this photograph was taken we've seen open lake water when the still-air temperature was - 22°F (-30°C). But at those same very cold temperatures, when the wind drops the lake begins to freeze, as we show in our next photograph below.

When water at the surface is cooled to 4°C or 39.2°F it has reached its maximum density - a bit before it would freeze (which occurs at 0°C or 32°F).

This colder water begins to sink downwards through the warmer, less-dense water below, assuring us that deeper water is at a temperature above-freezing.

The fact that ice, less dense than water, floats also assures us that any ice will be at or near the water surface.

When water at the surface is cooled to 0°C and if the water is relatively calm so that there is not much active mixing of the cooled surface water layer with warmer water from below, the first ice forms as a thin layer.

Freezing Burlington Bay, Two Harbors MN (C) Daniel Friedman at InspectApedia.com

Photo above: with the reduction in wind and waves the surface of Lake Superior begins to freeze, as shown in our photo of Burlington Bay, Two Harbors MN in February 2018.

Our next photo, shown below, illustrates the tremendous power of wind and waves on the big lake: huge chunks of ice are broken up and tossed shoreward by wind and piled near shore until eventually temperatures fall low-enough and wind becomes mild-enough that the whole mess freezes solid.

On the Arctic Ocean, much larger than those in our Lake Superior photo below, one might imagine “smooth sailing” or smooth snowmobiling or skiing over miles of Arctic ice. But massive ice ridges form to create the most difficult and time consuming obstacles for explorers. - LC

Lake Superior frozen solid in February 2019, Two Harbors MN (C) Daniel Friedman at InspectApedia.com

Watch out: if you are not familiar with safe procedures for walking on or exploring frozen lakes, stay off the lake surface. Failure to spot thin ice, a condition that can occur in some areas even when surrounding ice is several feet thick, means that you can suddenly fall through the ice into freezing water where death is usually quick.

In the winter of 1953, our neighbor Stevie Stevenson, ever the explorer, walked out onto the frozen surface of the University of Richmond lake where, at the lake's Western end and 100 yards from shore, he fell through the ice. He was "just testing the ice" according to the newspaper. Stevie was rescued by the InspectApedia editor's father.

Details are at SKEPTICAL BOY, 11, LEARNS ABOUT ICE on U. of R. LAKE [image file] as reported in the Richmond News Leader in the winter of 1953.

Continuing: With continued exposure to below-freezing air, the surface is further cooled and the thickness of the ice layer at water top increases.

As ice is less dense than water it floats or remains at the top surface.

At this point we can be pretty-much assured that deeper in the water we've got water that is at least 4°C warmer than at the surface.

Now if we mix, agitate, or stir-up the water near the surface, say from waves on Lake Superior, the added energy from stirring itself is very small, not enough to much-prevent freezing.

But the mixing of the warmer water from below with the cooling water at the surface will slow the freezing of water in a stream, or on a body of water in windy conditions, or on the surface of water that is being stirred up by running stream water, or by an air bubbler, dock-de-icer or boat bubbler like those described above.

So if we agitate a body of water whose surface is exposed to freezing temperature or below, that water won't begin to freeze until the entire thickness or body of agitated water has been cooled to 0°C or below.

 

Research on the Freezing Point of Water vs Burst Pressure of Building Piping Systems

Vrbka & Jungwirth illustrate the effects of the presence of salt in water during freezing - cited & discussed at InspectApedia.com

 




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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2023-05-10 by InspectApedia Editor (mod) - How does the amount of salt in a water solution effect the force of expansion when freezing?

@John from Brisbane,

Thank you so much for a wonderful question.

Bottom line answer: there is little or no effect of salt on the freezing FORCE of water as it forms ice and thus expands in volume.

Details:

NASA Aquarius (an education arm of the US Space Program) has noted, in an education bit on freezing of sea water, that [Paraphrasing by InspectApedia] salt ions (NaCl) in water arrange themselves around the water molecules (H2O) thus interfering with the tendency of the water molecules to form into spaced-out crystals as ice at freezing temperatures.

The effect is that the freeze-point of water containing salt is lowered (which is why "road salt" can act as a de-icer). But at very cold temperatures starting around 15 degF, the temperature effects leading water molecules to arrange themselves into a hard crystalline form (ice) overcomes the interference effects of the salt molecules, and water freezes solid.

(That's why sea ice is concentrated at the much colder temperatures closer to the poles of the earth.)

Here's reasoning that gets us closer to your question of the effect that salt in water has on the freezing force (expansion) of water or ice:

As water freezes the salt molecules are in effect pushed aside - that is, the H2O molecules join together, squeezing out the NaCl molecules.

As a result, frozen "salt water" will have very few salt molecules in that structure. (Vrbka 2007)

Therefore we conclude that once water is actually freezing, salt that it contained previously, has little or no effect on the expansive force of the ice itself.

Some wonderful illustrations of the process of freezing water and the presence and then squeezing out of salt molecules are offered by Vrbka and Jungwirth, cited below and illustrated here with a snapshot excerpted from that article.

Where does the salt go when salted water freezes?

In lay terms, it's "pushed aside" or outside of the ice itself. We think that's why you may see concentrations of salt "crust" on surfaces or at the edges of where salt was used as a de-icer. See Bing- 2015 for more on this.

Sources:

Liu, Jianpeng, Ping Yang, and Zhaohui Joey Yang. "Water and salt migration mechanisms of saturated chloride clay during freeze-thaw in an open system." Cold Regions Science and Technology 186 (2021): 103277.

Vrbka, Luboš, and Pavel Jungwirth. "Molecular dynamics simulations of freezing of water and salt solutions." Journal of Molecular Liquids 134, no. 1-3 (2007): 64-70.

Abstract
Results of extensive molecular dynamics simulations of freezing of neat water and aqueous sodium chloride solutions are reported. The process of water freezing in contact with an ice patch is analyzed at a molecular level and a robust simulation protocol within the employed force field is established. Upon addition of a small amount of NaCl brine rejection from the freezing salt solution is observed and the anti-freeze effect of the added salt is described.

- Copy here at
https://inspectapedia.com/plumbing/Molecular-dynamics-simulations-freezing-water-salt-solutions-Vrbka.pdf

"Can Sea Water Freeze" Aquarius Education & Public Outreach [from NASA) - https://salinity.oceansciences.org/learn-more.htm?id=12

Also relevant to the article above on this page

Amini, Behnam, and Saleh Sharif Tehrani. "Simultaneous effects of salted water and water flow on asphalt concrete pavement deterioration under freeze–thaw cycles." International Journal of Pavement Engineering 15, no. 5 (2014): 383-391.

Bing, Hui, Ping He, and Ying Zhang. "Cyclic freeze–thaw as a mechanism for water and salt migration in soil." Environmental Earth Sciences 74 (2015): 675-681.

On 2023-05-10 by John from Brisbane

How does the amount of salt in a water solution effect the force of expansion when freezing?

On 2023-05-01 by InspectApedia Editor (mod) - What is the possibility of freezing the water in the cooler of a gas turbine engine inlet air cooler with zero flow of chilled water

@Roberto Guasch,

Wow what a cool question, no pun intended.

If there is no water flowing through a tube at 46 degF there is no freezing risk from the surrounding environment, so I infer that you're asking about a cooling or super cooling effect that occurs in gas turbine engines.

So with apology, I think there is a gas turbine engine engineering theory and question, and maybe a test question lurking here that's beyond our expertise. I do know that there are several different types of coolers and of cooling going on, and you and your (I'm suspecting) test question haven't specified which we're applying:

- fogging
- wet compression
- evaporative cooling
- vapor compression
- vapor absorption cooling
or a combination with thermal energy storage

As wikipedia explains,

Good luck on your exam.

On 2023-05-01 by Roberto Guasch

What is the possibility of freezing the water in the cooler of a gas turbine engine inlet air cooler with zero flow of chilled water through the tube at temperature of 46 degrees F and Relative humidity of 65 % cooler tube made of copper

On 2022-12-19 by Mark

@InspectApedia (Editor), Excellent comments. Thank you so much for broadening my perspective on this.

On 2022-12-03 by InspectApedia (Editor)

@Mark,

Continuing:
and from engineeringtoolbox dot com we have this nice summary

Specific volume is the inverse of density, or the ratio of the volume to the mass of a substance:

v = V/m = 1/ρ [1]

where

v= specific volume, units typically [cm3/g] or [ft3/lb]
V = volume, units typically [cm3] or [ft3]
m= mass, units typically [g] or [lb]
ρ= density, units typically [g/cm3] or [lb/ft3]

It's interesting that at 4 °C or 39.2 °F the density of water is greatest at above freezing (this is why ice floats)

FWIW here are two example data points:

at 35degF for water the specific volume is
1.00007 cm3/g
or
0.11983 US gallons (liquid) / lb

At 32 degF the specific volume of water changes to

1.00013 mg3/g
or
0.1184 US gallons (liquid) / lb

On 2022-12-03 by InspectApedia (Editor) - even a small expansion can cause damage if the expansion exerts tremendous force across a very small area

@Mark,

Thank you for the discussion. In fact, even a small expansion can cause damage if the expansion exerts tremendous force across a very small area. That's how we see concrete and masonry damage in tall buildings. However if the freezing is occurring in a plastic line that tolerates the increase in volume there could be no damage at all. So the surrounding materials are important.

The volume increase of about 9.05% when water has frozen to solid ice is consistent with the pressure increase.

It may be helpful to think of Boyle’s Law - though that law pertains specifically to gases not liquid:

P1V1 = P2V2 as we discuss in this article series, or in text:

At constant temperature, the volume of a fixed amount of a gas is inversely proportional to its pressure.

I would add that water freezing in a cylinder can do some pretty strange things. It doesn't necessarily expand uniformly in all directions but will in fact tend to extrude itself when it's in a cylinder such as a pipe or a downspout. I've seen water for example freeze and form a column of ice that pushed out the top of an open downspout or pipe.

On 2022-12-02 by Mark

@InspectApedia (Editor), Thanks so much for your response; I was amazed to find a place to be able to ask about a technical issue like this--and especially to get an answer. I totally get the very high pressures generated inside a closed container with freezing water.

It just seems to me like there would be an additional equational consideration in terms of the volume being frozen, but I guess not? We are talking about a total volume of about 2.4 ml in a 12 inch stretch of plastic tubing, or about 0.22 ml/in. With a 9% increase in expansion, as you say, at 17 degrees F, an expansion to 0.24ml/in. I'm not sure that would cause a failure. Maybe. Thanks...

On 2022-12-01 by InspectApedia (Editor) - different expansion forces for freezing ice

@Mark,

Various sources give different expansion forces for freezing ice.

Depending on its state, freezing water (or ice as temperatures continue to drop past freezing (32°F towards 0 °F) can expand by as much as nine percent at a maximum force between about 25,000 and 114,000 psi.

On 2022-12-01 by Mark

How much pressure does frozen water create in a one foot long, 1/4 inch plastic tube, ID 1/8 inch with a volume of about 0.15 cubic inches? This is in plastic tubing rated to -40 F with a pressure rating of 160 PSI that will supply an outdoor fishpond in a zone that has freezing temps of 17-20F at night and typically warms above freezing in the daytime.

It seems the volume is an important consideration, but I can't figure out the math. (edited changed photo format to JPEG -- markbieri@gmail.com)

freezing 1/4" plastic tubing (C) InspectApedia.com Mark

On 2022-02-09 by Inspectapedia Com Moderator - How do you determine whether it is expanding ice or water pressure that causes pipe bursts?

@John King,

In freezing conditions such as those we describe in this article, burst pipes are caused by pressure from ice - which is a tremendous force when water freezes, as we describe above on this page.

In freezing conditions, burst pipes are not ever caused by water pressure itself. Building water pressure at normal delivery levels - say between 20 and 70 or even 80 psi are nowhere near the bursting pressure of plastic, steel, or copper piping.

For example, the working pressure of 1-inch L-copper piping is 420 psi, and the actual burst pressure is around 2650 psi.
Even the lower of these two numbers, the working pressure, is more than four times the water pressure delivered in any residential structure, none of which would be expected to even approach 100 psi.

From the article above,

As the water-ice temperature continues to drop to 0°F, the forces involved range between 25,000 psi and can continue to reach 114,000 psi.

As you can see that ice-force is enormously greater pressure than will ever be achieved by water pressure itself.

On 2022-02-09 by John King

Hello! Thank you for providing valuable, distinctive information!

Regarding your two above photos for lateral and horizontal pipe breaks.... as I understand, your writing says expanding ice caused breaks. Other webpages' information would suggest that pipe ice clogs created water pressure that caused these breaks. How did you determine whether it was expanding ice or water pressure? Was there a visual method?

On 2021-11-28 by Inspectapedia Com Moderator (mod) - Explain the change in water temperature caused by bubblers or water agitation: When will the Lake Freeze Solid?

@Jake,

Thanks for the interesting comment/question on thawing ice using air (or as we will explain, any source of movement in water).

We don't have all the data we'd need to offer a technically-complete answer (with numeric data) to your question, but below is a general explanation of the thawing effect of air bubbles or air movement in freezing water.

Remember that lakes and rivers freeze from their surface downwards when air temperatures fall and remain below freezing.

The top inches or feet of water are cooled by freezing-air temperature and begin to form ice.

Ice, as you will read on the page above, expands or occupies more volume than the water that formed it, so it wants to float or remain on the top of water. And cooled water, down to 4C, sinks.

So when air temperatures are very cold and as a water surface begins to freeze, water temperatures below the ice level will be warmer than at the surface.

What about your air pumped bubbler pipe? How is that working to melt ice?


The photo shown above is excerpted from an Amazon advertisement for the Ice Eater P500, a 1/2 Horse Power Pond, Lake, Ocean and Dock De-Icer, produced by Bearon Aquatics.

[Click to enlarge any image]

  1. You are sending air down a pipe into water below a frozen surface.

    The air is at a temperature above freezing, so it is bringing some heat into the frozen area.
  2. You are agitating the water,

    causing the movement of warmer water up towards the freezing or frozen surface.
  3. Warmer water rising to the surface melts the ice.

    If the volume and speed of warmer water moving to the surface is sufficient, that melts the surface ice and then prevents ice from forming.

Agitating water to send a warm water current upwards towards the surface by using air bubbles is an old, w established method to prevent freezing that has been in use for at least a century - we used to install bubblers to prevent water from freezing against and crushing the hulls of small boats on the Hudson river in New York.

Bubblers are widely used to prevent ice damage to docks and similar structures.

Pond or lake or dock freeze protection, boat bubbler, from Kasco at InspectApedia.comIn those installations the bubbler is keeping water around the boat's hull in motion - bringing up warmer water to the surface where dropping air temperatures remove so much heat from the water that left alone and still the water would freeze.

It's a combination, then, of movement (running water freezes later than still water) and heat transfer (lower warmer water is being brought to the surface) that explains how a boat bubbler system works and that may explain what you observed.

To be clear, air isn't the only way to agitate water and thus to prevent ice formation or to melt ice such as around docks or boats.

The Kasco brand lake and pond deicer or "dock bubbler" shown below uses an electrically-driven propeller to move warmer bottom-water upwards towards the water surface.

Excerpting from the product-description

This dock deicer bubbler is specifically designed with a high efficiency motor and propeller with 1750 rpm that creates a directional flow of water.

This pushes warm bottom water to the surface and provides an ice-free area of protection around your boat, dock, pier, or other in-water property.

More about freeze-proofing a building including pipe freeze protection can be found at

WINTERIZE - HEAT ON PROCEDURE

On 2021-11-28 by Jake - Can you explain to me the change in water temperature caused by this air pressure?

I have a 36" steel pipe, vertically entering the water. one the surface the 36" pipe is capped and under the water ( Approximately 7feet below the surface) the end of the pipe is open.

I hooked a compressor up to the pipe, and began filling it with air, until bubbles started to form under the surface of the frozen surface.

So in my mind I have created enough pressure to force the water down far enough that the air started to come out the end of the pipe under the frozen surface.

Then the water started to melt at the surface until the entire surface around the pipe had thawed out, and in fact further down the river a patch or two started to melt as well.

Can you explain to me the change in water temperature caused by this air pressure, is there a table out there somewhere that will tell me all of this.

I understand the pressure pushing the water out, but I cannot mathematically explain the change in water temperature around or in the pipe?

Reader Question: How do I prevent the frost from pushing my drain pipe upwards

4/16/14 Anonymous said:

How do I prevent the frost from pushing my toilet drain pipe up through the floor and dislodging the toilet from the flange on the floor. This is at a cottage.

Reply:

Anon, you ask an important question, for which, with apology, I have to speculate a bit to try to answer.

Normally the toilet waste line doesn't push up through a floor.

To fix your frost-heaved waste piping we need to know why it's happening. I speculate that

A "band aid" approach that I don't like is chopping out a section of flooring and packing foam insulation around the drain line in the fantasy that we can protect it from frost heaves. We need to either install construction components below the frost line or keep water out from below the foundation and slab.

Instead, start outside looking at where and how water is saturating the ground under your foundation and slab. While you're at it, and since this is a cottage that perhaps is not occupied and heated all year, also take a look

at WINTERIZE - HEAT OFF PROCEDURE

Reader Question: what's the actual temperature at which building pipes freeze?

Thank you for your helpful information about freezing water pipes!

But I fear that your reference to 20°F will mislead many of your readers. It seems to be generally said on the Internet that when outdoor temps get down to 20°F or below that freeze/break of indoor pipes becomes more likely. This is quite different from the actual temp of the indoor pipe itself, that may freeze/break

It takes over 1000 psi to lower the freezing point of water by one degree F! It seems inevitable that the vast majority of water pipes would freeze (and presumably break?) long before the real temp of the pipe and the water inside got down to 20°F, which would require a pressure of over 10,000 psi.

-k seeking facts and understanding in Boston

As we elaborate below, while water begins to crystallize into ice at 0°C (or 32°F), its expansive forces generally do not cause water pipes to burst until temperatures further fall to around 20°F.

The actual burst point for freezing pipes has more variables including the pipe material, thickness, and even possibly its overall diameter and shape. But 20°F is a good number for the freeze point of pipes.

pressure lowers freezing point of water a slight amount

* www1.lsbu.ac.uk/water/density_anomalies.html Explanation of the Density Anomalies of Water

"Pressure reduces ice's melting point (13.35 MPa gives a melting point of -1 °C)"

"In water, this line is backward sloping with slope 13.46 MPa ˣ K-1 at 0 °C, 101.325 kPa."

Many people want to know if the pressure in water pipes lowers the freezing point. Almost all Internet info including WP is not helpful: science phase diagrams in unfamiliar units that do not show appropriate detail, only that the melt temp does not vary much with pressure under common water pipe conditions.

It would be great to have a graph of temp in C and F (not K) vs pressure in PSI for 0-10,000 PSI for inclusion in WP articles. Until then, 13.35 MPa converts to 1936.25 psi (pounds per sq. inch). We could say something like:

* Pressure in water pipes reduces the freezing point slightly: a pressure of 1936 psi lowers the freezing point to -1 °C.

The graph in the good Martin Chaplin LSBU article appears to show that 100 MPa (14,500 psi) would lower the melt temp by about 10 °C.

Typical water pipe pressures are usually around 100 psi, which apparently would lower the freezing point by a small fraction of a degree. If the slope at zero is 13.46 MPa per degC, that works out to 0.051 °C (0.092 °F) for 100 psi.

Or maybe a more useful rule-of-thumb to remember would be 1000 psi lowers melt point by about 0.5 °C (0.9 °F).

It would be a relevant factoid to include in some articles, if we could be sure of the science/physics facts. - Anonymous by private email 2018/01/11

Reply:

Thank you for the comments. In our article we do mention that the impact of water pressure on freeze-point of water in pipes is very small - perhaps I should say "not really a factor" because of the numbers involved.

About the freeze point, as we both know that water freezes at 32F (at sea level, for fresh water), [actually water super-cools a bit before it freezes] we can pretty much figure that water in pipes at that point, too, depending on a range of factors we list in the article above.

The 20 degree figure is, I agree, a subjective ballpark number based on field experience for occupied homes during a temporary power outage. Certainly a home that is unattended and /or that remains un-heated for a protracted period is likely to have frozen pipes at somewhat higher temperatures.

A separate question is the hard freeze temperature and the relationship between that and burst copper pipes. I pose that colder temperatures increase the risk of bursting - but we need some science to support that claim.

I'll review the article to add our discussion, for which I'm grateful, and we can both look for more data.

On 2021-03-19 by (mod)

And take a look at the company's "Green Stripe" pipe described as

"The Professional Choice in 100 psi rated CSA grade cold potable water certified poly pipe. The most popular uses include well and lake water intakes, commercial and residential irrigation systems and lake and farm pond water distribution. "

On 2021-03-19 by (mod)

@KenB,

sorry to say I don't know for sure;

I would give the manufacturer of your pipe a call to ask their advice.

For example, if you are using Blue Stripe IPEX from IPEX Homerite Products, that pipe is rated to withstand 100 psi. Your starting pressure is probably very low, just a few psi, so your pipe might be fine. Give IPEX a call and ask them - and do let me know what you're told.

IPEX HomeRite Products
1425 North Service Road East, Unit 3
Oakville, ON L6H 1A7
Tel: 289-881-0120
Customer Service:
Toll free: 866-777-8023
Fax: 905-670-5295
info@ipexhomerite.com
sales@ipexhomerite.com

I can add that recently we lived in an off-grid cabin in the northern U.S. during temperatures of -24 degF for several weeks and though our PEX water tubing froze, it did not split; so at least in that small-diameter (1/2 " PEX) and under those conditions we were OK. I was worried that even if the PEX didn't split there might be brass fittings with water in the that might freeze and break, but fortunately our pipe routing was all PEX, no fittings, in the area of freezing.

For lakeside water supply systems that must be kept operational in winter I've participated in the installation of an air-pump system that in essence pressurised the piping with air sufficient to push water down below the ice level in the lake each time the pump was turned off.

For lakeside water supply systems like yours that are not used at all during winter, emptying the piping is probably the simplest, and least-costly insurance against freeze damage to the piping, fittings, and pump.

On 2021-03-19 by KenB

@danjoefriedman,
Yes. I it will freeze at the top for sure. I forgot to add that I would use blue, or blue stripe pipe which has a much higher rating than what most people use for cottage/pull it out and empty it in the fall water systems. I’m wondering if given the higher rated thicker wall blue rated pipe and it’s flexibility would it be able to withstand freezing without splitting for the 1-2 feet out of the ice with water in it, as I would put a T drain fitting just above the water line.

On 2021-03-18 by (mod)

@Ken B, HDPE piping can withstand some freezing; as Mark Cramer says ... it depends: on the lowest temperature and on the particular freezing forces.

At the lakeside water supply systems with which I'm familiar the water is pushed down the pipe to several feet below the lake surface so that only air is in the pipe in the sections exposed to freezing.

In your description I would expect your pipe to freeze.

See details at

WATER PIPE FREEZE PROTECTION https://inspectapedia.com/plumbing/Pipe_Freeze_Protection.php

On 2021-03-18 by Ken B

Will modern polyethylene 1” 160psi or 200psi well water pipe coming out of a lake and drained to a couple of feet above lake level with water from that point down to the pump well below the frozen ice be able to expand and withstand the expansion of the frozen ice and not burst in that upper section of the pipe. It’s a question I think many cottages have and there doesn’t seem to be any info out there on the internet.
water in it

On 2020-12-29 by (mod)

Joel

The purse you suggest is not feasible nor reliable. Water piping will not be dead level throughout it's runs.

Plastic pipe can be damaged by freezing as may be it's connectors, fittings, fixture, though it is more tolerant of freezing than metal pipes.

Here in northern Minnesota in recent temperatures well below freezing I've seen some PEX freeze solid then than without damage... yet. Harder plastics like CPVC are more vulnerable as may s be brass elbows, couplings, unions, etc. used in PEX systems.

On 2020-12-29 by Joel House

I have a bet with a friend. In a manufactured home CVPC piping system is it required to air purge the entire system so that there is less than 1/2 the diameter of the CVPC pipe to avoid ice expansion contributing to split pipes? If there is a belly in a pipe will the water freeze and burst the pipe or will it expand upwards on both sides of the belly?

On 2014-04-17 by (mod)

Anon, please see your question and my detailed reply in the bottom of the article above = there I could include links and added information.
Let me know if you have further questions.

Daniel

On 2014-04-16 by Anonymous

How do I prevent the frost from pushing my toilet drain pipe up through the floor and dislodging the toilet from the flange on the floor. This is at a cottage.


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