Wet Piping Insulation?

[tcatt]

Replacing some electrical heat trace on 2" high temperature HRSG drain lines. Current insulation is wet and froze during the winter; piping is both horizontal and vertical.
A few questions.
1) Mineral Wool vs Fiberglass: which is better if there is some water ingression in system. ( Operation Temp. as high as >900F)
2) Any Practical way to test for moisture, ( and I mean wet enough to freeze), without removing the lagging.
3) How much moisture can insulation absorb before it is useless?
4) Data to support need to replace vs moisture
5) Insulation installation practices to be used as quality control when contractors install lagging, best practices to properly seal system.

If I need to provide additional information... no problem.

I have searched for concise and practical information to use to help us manage this continuing problem with wet insulation, and looking for some advise.

 

[LittleInch]

Fibre type insulation relies upon being dry and trapping air in the fibres to provide insulation. Once it gets even slightly wet, the insulation properties vanish.

So, IMO, the answers to your questions are:
1) Neither
2) Not that I am aware of
3) Only a small amount
4) If it's getting wet you need to rpelac eit as insulation properties disappear, not to mention the Corrosion under Insulation issue...
5) vigilance

I think you need to look at alternative solid sealed types of insulation such as Foam Glas which is 100% sealed. Might be a bit more initially but will seal, work and stop all the repairs you're having. Their website isn't great, but I think you'll get the gist. I don't work for them but have used it and think it is good stuff in the right place.

http://www.industry.foamglas.com/en...ing_equipment/above_ambient_high_temperature/

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[trashcanman]

Ditto to what LI said.
If the line is heat traced, how did it get cold and wet?
Please define "high temperature HRSG" What temperature?

If the temp. is <= 220 Deg.F, use Armaflex. Great barrier against moisture, easier and cheaper to install than foamglass.

 

[bimr]

In addition to what the previous posters said, if all of the insulation failed, the insulation probably was not installed correctly in the first place. Perhaps you need a new Contractor.

Note that the insulation jacket is supposed to stop the water penetration.

 

[BigInch]

Nothing lasts forever, especially in the presence of unequal coefficients of temperature expansion, hot inside, cold outside temps, rodents and birds, etc. Expansion inside, contraction outside = cracks.

Watch the max service temperatures of any insulation you choose. Little Inches suggestion of Foamglas looks good, but you'll need the Foamglas composite formula. Others are over or near their service temp limits.

HRSG heat recovery steam generator.

I hate Windowz 8!!!!

 

[tcatt]

Thanks, for your replies.

The temperatures and vibration eleminate foam glass materials for the most part. One of the things that I would like to put into place is a set of best practices and ASTM standards to use as best practices.

Anyone ever put together a plant set of standards or best practices for quality control.