Failing chilled water pipe insulation 1

[Cool_Controls]

I work on a University campus that has been experiencing degradation\failure of chilled water pipe insulation. The installations are all 10 to 20 years old utilizing Armaflex closed cell elastomeric foam, the failure is always on the supply pipe (chilled water supply temp is approx. 42°F, return is 48 to 50°F). The insulation begins to wrinkle, pucker, and collapse in on itself resulting loss of thickness and R-value eventually leading to sweating pipes. This is occurring in numerous buildings of all different types (Labs, Offices, Dorms). Has anybody seen anything like this or have an idea what is causing it?

 

[HVAC-Novice]

What's the perm rating? If perm rating is high, water vapor penetrates the insulation and condenses. That water I suspect dissolves the adhesive.

Has this damage occurred just recently, or has it been deteriorating throughout the entire life of the system?

 

[Cool_Controls]

Usually it takes several years before it starts to be noticeable, advertised permeability is 0.05 perm-in of thicknesses up to 1", 0.08 perm-in for 1.5 to 2"

 

[MintJulep]

Corrosion Under Insulation (CUI)

This document from Armaflex shows similar symptoms, although it's not very informative:

https://www.armacell.us/fileadmin/u...erated_Systems.Technical_Guide.EN.US.2020.pdf

This explains how Armaflex is great, and the best insulation to use to prevent CUI - yet.....

https://local.armacell.com/fileadmin/cms/downloads/know-how/en/Know-How-Part-4_Risk_of_CUI_EN.pdf

 

[Cool_Controls]

Great find!!! I'm familiar with CUI, but never knew it could cause cell collapse. Thank you.

 

[Compositepro]

Armacell calls that insulation FEF (Flexible Elasotmeric Foam) but does not say what the elastomer is. It looks like polyurethane, which is susceptible to hydrolysis with time. That results in eventual disintegration of the foam. Exposure to water and humidity accelerates this.

 

[LittleInch]

Have you got any cut outs from those collapsed sections? What do they look like? IS the pipe corroded?

Is that line where the installation gap was if this is "split" post install insulation?

Very interesting that there is only 5C difference between the two lines.

Is there ANY possibility that the supply line could have gone to or below freezing at any point. Hence any water or moisture could freeze inside the insulation? Might only be for a few hours, but once those bubbles break, they don't repair themselves?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[FacEngrPE]

Having seen the results of long term operation of chilled water systems with most of the available insulation systems,
[ul]
[li]Armaflex[/li]
[li]Foam Glass[/li]
[li]Fiberglass[/li]
[li]Cork[/li]
[/ul]
Today I consider a CUI coating vital to long term performance of cold piping, unless the piping material is inherently non corrosive. In the past 20 years CUI coatings have improved to the point where their is no question as to the benefit of CUI coatings.

Even with CUI coatings, ongoing maintenance of insulation systems - particularly components that keep the system dry is important and often neglected.

 

[vij36]

We had a situation once we were considering hdpe pipes instead of MS. But that idea has been dropped. Still wondering polyethylene ... is it a choice for CHW piping?

 

[FacEngrPE]

HDPE is generally a fine piping material, but it is rather flexible and as a result, requires lots of supports. HDPE also requires careful expansion design.
Most of the information needed for design can be found at the Plastic Pipe Institute

https://www.plasticpipe.org/Municip...ications/Download-HDPE-Handbook-Chapters.aspx

 

[PagoMitch]

I would pull some insulation off and check the pipe itself.
I would suspect an insufficient insulation thickness is allowing water to condense within the void between the insulation and the piping, and eventually "leaking" out at insulation seams; my guess is that is why you see the water stains in your last pic.

Once it is wet inside, the only way to dry it is to shut the plant down and pull off the old waterlogged insulation.
Once the pipe is dry, if you glue-on the first layer, it will help eliminate the voids.

You may also need more than one layer.

 

[BronYrAur]

My guess is a failed vapor barrier which let moisture in to condense and corrode the piping. That and/or leaks. I have seen this is in older facilities where you can literally feel pools of water in the insulation that is sagging. I am no insulation expert but I "always heard" that Armaflex was the worst with Fiberglass being just a little better. Cellular glass is much better.