Minimum burial depth of insulated pipe to avoid freezing (moving fluid)
Minimum burial depth of insulated pipe to avoid freezing (moving fluid)
(OP)
Hello everyone
I have been looking in to the required minimum burial depth of insulated pipes and I have become stuck.
I have read through the attached pdf however I am getting weird values (0.00034mm depth).
I have searched on-line for a while but no joy, there where a few pieces of information but none that fitted my requirements
Does anyone know of a formulae to calculate the minimum burial depth of an insulated pipe to avoid freezing?
Thank you for your time
Josh Man
Beng Mechanical engineering
I have been looking in to the required minimum burial depth of insulated pipes and I have become stuck.
I have read through the attached pdf however I am getting weird values (0.00034mm depth).
I have searched on-line for a while but no joy, there where a few pieces of information but none that fitted my requirements
Does anyone know of a formulae to calculate the minimum burial depth of an insulated pipe to avoid freezing?
Thank you for your time
Josh Man
Beng Mechanical engineering





RE: Minimum burial depth of insulated pipe to avoid freezing (moving fluid)
You are working in Chapter 12, right?
Someone has supplied you with the soil conditions?
They should also have told you the depth of freezing.
= = = = = = = = = = = = = = = = = = = =
Plymouth Tube
RE: Minimum burial depth of insulated pipe to avoid freezing (moving fluid)
yes i am currently on page 12-14
using X = m(Ig)½ that expands in to using the correction coefficient, my main issue is how to calculate Ig?
The pipe will be buried in London and have to withstand the winter months.
when you say depth of freezing is that frost permeability?
Thanks
Josh
RE: Minimum burial depth of insulated pipe to avoid freezing (moving fluid)
α is the soil thermal diffusivity in [m2/s],
Tsurf is the soil surface temperature [°C],
Ti is the initial soil temperature [°C]
x is the depth of the water pipe [m]
t is the time the soil is exposed at Tsurf [s]
T(x,t) is the temperature at depth x and time t
[T(x,t) –Ti]/[Tsurf – Ti] = erf [x/(2sqrt(αt))]
Where erf is the error function (http://www.miniwebtool.com/error-function-calculat...)
You put T(x,t) = 0 °C and solve for x
RE: Minimum burial depth of insulated pipe to avoid freezing (moving fluid)
"Heat transfer a practical approach" by Yunus A. Cengel (2nd edition - McGraw - Hill):
4–3 Transient heat conduction in semi-infinite solids
RE: Minimum burial depth of insulated pipe to avoid freezing (moving fluid)
RE: Minimum burial depth of insulated pipe to avoid freezing (moving fluid)
The value you get with the approach above is conservative as it doesn’t take into account pipe’s insulation.
RE: Minimum burial depth of insulated pipe to avoid freezing (moving fluid)
http://www.cdeep.iitb.ac.in/nptel/Mechanical/Heat%...
the link above is a similar calculation to yours.
how would I go about incorporating the pipes insulation values in this calculation?
Thanks
Josh
RE: Minimum burial depth of insulated pipe to avoid freezing (moving fluid)
There may be a much easier solution. I know that AWWA D100 has a figure which shows the minimum cover over buried pipe to avoid freezing. There may be a similar BS that covers the same material. Alternatively, you could look at weather conditions and select an similar US city and use that value as a starting point.
RE: Minimum burial depth of insulated pipe to avoid freezing (moving fluid)
That detail shows the depth can be reduced to as little as 0.6 m (2 feet), when insulated with 3" thick by 4-ft wide insulation.
I'd think you could select annular insulation to allow as little as 2' bury also.
RE: Minimum burial depth of insulated pipe to avoid freezing (moving fluid)
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RE: Minimum burial depth of insulated pipe to avoid freezing (moving fluid)
RE: Minimum burial depth of insulated pipe to avoid freezing (moving fluid)
i will have a read through, it looks very retro.
RE: Minimum burial depth of insulated pipe to avoid freezing (moving fluid)
There's been a lot of advances since that old Corps paper. Alaska DOT offers a free dos-based program to solve this, called "BERG2". Even that program is 20 or so years old. It is most useful for determining insulation of roadways, doesn't apply well to narrow elements like pipes.
RE: Minimum burial depth of insulated pipe to avoid freezing (moving fluid)
RE: Minimum burial depth of insulated pipe to avoid freezing (moving fluid)
thanks for all the responses, I think I have worked it out.....
I have calculated the depth of pipe with no insulation, I have then calculated the temperature of the OD of the pipe and worked out the heat loss with the insulation.
I have then done the same calculation using the thermal diffusion for the insulation and taken the insulation depth from the non insulation depth.
hopefully this is done correctly?
RE: Minimum burial depth of insulated pipe to avoid freezing (moving fluid)
RE: Minimum burial depth of insulated pipe to avoid freezing (moving fluid)
I have used the formulae from the link below, I have then calculated the outer casing temperature and then used this value to calculate the time taken to fully penetrate the PU foam and used the values to calculate the minimum depth after a specified time period - the time taken to penetrate the insulation of the pipe, sorry if I haven't explained this too well.
http://www.cdeep.iitb.ac.in/nptel/Mechanical/Heat%...
attached is my attempt :/ if some one would like to have a quick scan to see if I have made any major mistakes it would be appreciated guys.
Cheers
Josh