insulating polyethylene pipe for freezing

[elquesifilma]

We currently have a 4000 ft of 10 inch SDR 11 polyethylene pipe which we are planning on laying below ground for fresh water transfer (lowest temp ever recorded 5 F, normal low temp is 20 F). The reason for burying the pipe is that we are concerned with freezing.

The problem we have is that the field is congested and burying the pipe will be time consuming, and very costly.

We are looking into having at least 3000 ft of it laid above ground and insulating it with urethane an polyguard seal. My concern is that polypipe will expand , contract. Has anyone insulated poplypipe? if so will this last 10-20 yrs?. The pipe will be basically be laid on the ground with no supports

i appreciate any comment and recommendation

thanks in advance to all!

 

[pennpiper]

It is hard to have an opinion with so little information.
You did not say what the purpose of this line is. Yes, you said that the commodity is water but you did not say what kind of water, the temperature of the water or any clue as to the flow rate or frequency of use. You did not tell us where this project is.

If above ground you said:
"The pipe will be basically be laid on the ground with no supports" Why?
You also said:
"the field is congested and burying the pipe will be time consuming, and very costly." Why?

Almost everything you did tell us bodes of failure.

 

[elquesifilma]

More Information:

purpuse of the line to transfer fresh water SG 1. Freezing point 32F. Temperature of the water i would say 60 F, and constant flow. Allthough at upsets you can have no flow, where freezing is of concern. Its in new mexico where temperatures in winter go to 10 F.

The field is congested with spider web lines burried. To install this line we would need to hydrovac and maybe go 10-15 ft deep to route the line. So its costly and time consuming.

I am looking at laying the pipe on top of the ground with insulation.

 

[BigInch]

What is the freeze depth in that area? That tells a truer tale about the freeze protection you'll need.

Lay it on top of the ground and just pile dirt on it until you get to the freeze protection "depth" you need.

Expansion - contraction isn't a problem, if you snake it a little. Nothing inherently wrong with laying it on the surface, although 20 year life might be stretching it too much. I'm not sure about its UV stability.

Actually just little flow will be enough to prevent freezing. You might put a small drain valve at the low point and be sure you open it when you have no system flow and it also happens to be freezing weather.

Or you could heat trace it.

Or recirculating the water may be an option when the system is shut in.

Or put it inside another pipe and fill the annular space with insulation, if you think you have to go to extremes.

"Less than 1% of the energy moving a car goes towards the driver."
Amory Lovins - The Oil End Game

http://virtualpipeline.spaces.live.com/

 

[CarlB]

Depending on the flowrate & downtime frsome freezing may be tolerable. Annular ice could form and restrict flow for awhile, then melt during the day/warmer period. A property of HDPE pipe is that (supposedly) it can freeze solid (full of ice) & will not burst.