Buried Water Pipe - Blueboard Insulation
Buried Water Pipe - Blueboard Insulation
(OP)
In Northwest Montana we bury our water mains 6.5' below ground surface. However, when we can't achieve that depth we insulate the pipe w/ 2" thick blueboard a minimum of 2' either side of the pipe outer wall.
The rule of the thumb is 2" of blueboard insulation equates to 1' of pipe bury. We've been using this for along time, but now I would like to back it up.
Does anyone have studies to support this? Any other thoughts?
The rule of the thumb is 2" of blueboard insulation equates to 1' of pipe bury. We've been using this for along time, but now I would like to back it up.
Does anyone have studies to support this? Any other thoughts?





RE: Buried Water Pipe - Blueboard Insulation
Richard A. Cornelius, P.E.
WWW.amlinereast.com
RE: Buried Water Pipe - Blueboard Insulation
RE: Buried Water Pipe - Blueboard Insulation
So the answer to how much insulation is a function of water use. If you had a line with a constant demand flow at a high velocity, you would need no insulation. If you had a line that ran 15 minutes every month, you may not be able to get enough insulation.
From experience in my field, we found that our lines buried below frostline didn't freeze EXCEPT at dirt road crossings. It appears that the truck traffic compacts the soil and makes the heat transfer "faster" higher and the frostline is really slightly deeper.
RE: Buried Water Pipe - Blueboard Insulation
RE: Buried Water Pipe - Blueboard Insulation
The subgrade of a road should be more compact, thus containing less insulating air space and it is also likely that there is less water contained under the road, due to typical roadway drainage provisions, thus reducing the heat capacity of the subgrade material to roughly 1/2 that of any wet soil in the surrounding terrain.
Do you know the insulation value of your "blue board"?
http://virtualpipeline.spaces.msn.com
RE: Buried Water Pipe - Blueboard Insulation
RE: Buried Water Pipe - Blueboard Insulation
My personal observations tend to confirm that process as, during the begining of winter, I always seem to notice many days of intermitant ice warnings for road travel before there is a snow cover on the surrounding ground. Although later on, especially with a bright sunny day and on a black-topped roadway of a busy highway, it might seem to be the other way around. Black would adsorb much more heat than the surrounding white snow, which after a number of days would tend to raise the frost line below the road above that of the surroundings. Thinking about spring, I can't be so sure. Probably, like most things, timing is critical. Every process is dynamic in respect to one time frame or another. What you see depends on when and how long you look.
http://virtualpipeline.spaces.msn.com
RE: Buried Water Pipe - Blueboard Insulation
1. FACT: frost depth is greater in areas that are plowed. Snow cover in itself acts as insulation. So, areas where snow is plowed off of the surface (mostly for roads) always has deeper frost levels than areas where the snow is piled. It really has little to do the subgrade materials or lack of moisture in the roadbase. Case in point, if you leave a road unplowed all winter and let the snow build up on it just like the areas on the side of the road, you will not see a significant difference in frost levels.
To answer original poster, we bury water and sewer at least 8' deep. We also insulate with 2" blueboard (1" for every 1' of less cover), but I have yet to see any studies to support this, except that when it has been installed it has solved previous freezing problems.
RE: Buried Water Pipe - Blueboard Insulation
Frost line in a area takes into account the ground cover, snow, wind and such.
RE: Buried Water Pipe - Blueboard Insulation
work in Southeast Vermont
our standard detail
water
has 5.5' min
4' min insulated
sewer/drainage
5' paved areas
4' lawn areas
2' min insulated.
we specify 2" rigid polystyrene
RE: Buried Water Pipe - Blueboard Insulation
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