Preinsulated Piping Experience
Preinsulated Piping Experience
(OP)
Does anyone have experience with preinsulated piping installed underground in a wet environment (high water table)? What materials are recommended for the insulation, conduit and outer shell?
Have you experienced ID corrosion of the steel conduit due to water ingress into the insulated annulus around the carrier pipe?
If so, what were the sources of the water ingress?
Have you experienced ID corrosion of the steel conduit due to water ingress into the insulated annulus around the carrier pipe?
If so, what were the sources of the water ingress?





RE: Preinsulated Piping Experience
For cold and hot water applications, insulation generally consists of either piping covered with a foamed-in place polyurethane covered with a high impact resistant formed plastic covering.
For steam lines, preinsulated conduit is used with an annulus air space around the insulation.
You may be interested in pursuing a field-installed system that uses cellular glass covered with an asphaltic membrane and sealed with sealants.
Another possibility is loose fill consisting of calcium carbonate poured into the pipeline trench and surrounding the pipeline.
The best solution to prevent water infiltration would involve installing a perforated drain 6" below the bottom level of the pipeline. It is also important to very carefully consider the potential for damage to the insulation from uncontrolled pipe movement.
RE: Preinsulated Piping Experience
Systems up to DN800 are bing used for chilled water around the globe. No concerns about loss of integrity of the vapour barrier causing corrosion beneath the insulation.
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RE: Preinsulated Piping Experience
RE: Preinsulated Piping Experience
Just for my benefit, why are you insulating a buried pipe? Here, we typically bury pipe uninsultated, and only insulate at the risers as they come up/down.
Although you did not state what is in the pipe, and the process conditions, have you considered a polymeric pipeline (HDPE or PEX)? Because these pipelines are "plastic", water corrosion is not an issue in buried service. Also, they have a temperature range of around -29°C to 140°C for HDPE (180°C for PEX).
One name brand is Fiberspar, out of Huston Tx. Their web is www.fiberspar.com.
RE: Preinsulated Piping Experience
RE: Preinsulated Piping Experience
Oh. Sorry, the poly pipes would not work.
I don't have much experience with steam pipeing (above or below ground).
I am curious though. Why are the pipes underground? Are you crossing under water or other obstacles. This is strictly my curiosity.
RE: Preinsulated Piping Experience
We didn't have to deal with lines below the water table, but we typically used Foamglas and just heavy tar paper tied on with wire. You might consider something like snow & ice shield - very sticky and hard/messy to work with, but likely as good as anything when combined with Foamglas. Plus it's much cheaper, and you can field fabricate around surprises.
RE: Preinsulated Piping Experience
You best option is to use a field installed instulation using cellular glass. The cellular glass can withstand the temperature, the glass structure also resists penetration from ground water.
It is recommended to use a perforated drain 6" below the bottom level of the pipeline to prevent the ground water from infiltrating the piping system. It is also important to very carefully consider the potential for damage to the insulation from uncontrolled pipe movement.
RE: Preinsulated Piping Experience
RE: Preinsulated Piping Experience
RE: Preinsulated Piping Experience