Insulation for -25C
Insulation for -25C
(OP)
Dear All:
I have brine pipelines in my site that are usually at -25C. Since my site is located in a subtropical region (very humid and hot weather), what happens is that most of the year I have lots of condensation in those pipes, that provoke energy ineficiency and cause disturbance in production areas. Actually these lines are insulated with green phenolic foam with vapour barrier and SS cladding. The fact is that I am already here for almost 3 years and there were insulations that were already replaced 2 times but the problem remains. My subcontractor says that the material specification is Ok, but I am having my doubts. Which type of materials would you recomend?
Just one remark: since my site works with some flamable products, I need insulation that in case of fire doesn't provoke toxic smoke.
Thanks a lot for your help.
PR
I have brine pipelines in my site that are usually at -25C. Since my site is located in a subtropical region (very humid and hot weather), what happens is that most of the year I have lots of condensation in those pipes, that provoke energy ineficiency and cause disturbance in production areas. Actually these lines are insulated with green phenolic foam with vapour barrier and SS cladding. The fact is that I am already here for almost 3 years and there were insulations that were already replaced 2 times but the problem remains. My subcontractor says that the material specification is Ok, but I am having my doubts. Which type of materials would you recomend?
Just one remark: since my site works with some flamable products, I need insulation that in case of fire doesn't provoke toxic smoke.
Thanks a lot for your help.
PR





RE: Insulation for -25C
Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA
RE: Insulation for -25C
Thanks a lot for your input, but I don't think that this is possible since I have brine pipeline spread all over the site, counting hundrends and hundreds of meters.
PR
RE: Insulation for -25C
Care to reveal the specific dimensions of a typical cross section?
Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA
RE: Insulation for -25C
My main brine pipe is 4" but then I have reduction to the equipments that can go down to 1 1/2".
Thanks.
PR
RE: Insulation for -25C
I've installed and operated Liquid CO2 (-29 oC), liquid NH3 (-33 oC), as well as liquid Oxygen, liquid Nitrogen & various refrigerant lines and equipment in the Caribbean (from Jamaica to Trinidad), in South America (Colombia, Venezuela, Peru, Bolivia, & Chile) and never experienced any problems with the insulation I specified and installed. I've used Styrofoam, foamed Urethane and FoamGlas types of insulation. For your application, I'd recommend the FoamGlas.
But whichever insulation type you employ, it is essential and very important to install a sucessful and reliable vapor barrier. Cold insulation, regardless of the type will fail miserably in not installed with a secure and reliable vapor barrier. That's the whole secret. I never used metal sheathing - even in the Amazon Basin. And my piping never formed external condensation. You have to calculate and apply the correct insulation thickness as well. FoamGlas, being composed of glass, will not burn.
I consider having to install insulation 2 times in 3 years in the middle of the Amazon jungle as an engineering failure. Something is being done wrong. It is either the insulation specifications or the installation - or both.
I hope this experience helps you out.
RE: Insulation for -25C
♣ Don't leat people walk on the insulated pipes,
probably penalizing the vapor barrier.
♣ Insulate flanges, and protruding surfaces.
♣ Keep away humidity: don't install the insulation
over wet pipes or under rain.
♣ Avoid thermal shocks (≥70oC/h)
♣ Follow Art Montemayor's advice.
Phenolic foams have a comparatively higher water absorption and may enable vapor ingress by means of the processes of absorption, condensation, hygroscopicity, permeability and capillary action, probably caused by their higher friability which, BTW, may cause debonding in sandwich structures.
RE: Insulation for -25C
vapor barrier is crucial as is sealing ends and longitudal seams. foamglas insulation is a suitable insulation for cold piping - used in cyrogenic gas plants along gulf coast and other high humidity areas.
good luck!
-pmover
RE: Insulation for -25C
The insulation manufacturer can throw some calculated figures about this issue.
For example, closed cell neoprene insulation designed for still air and with inside(duct) air temperature of 80C gives 8mm thickness but when the insulation is cladded with 40gauge aluminium, the thickness goes as high as 12mm to prevent condensation. I have been speaking to Armaflex for a detailed calculation but what I got was a case study, so far.
Regards,
RE: Insulation for -25C
htt
RE: Insulation for -25C
Now, just one thing:
How can I check the minimum thickness of phenolic foam do I need to insulate a 4"pipe at -25C with metal sheet cladding?
Thanks.
PR
RE: Insulation for -25C
You and I know you that the answer to last query is: you do your conventional calculations for heat transfer. One good source for a timely tutorial is:
http://www.cheresources.com/insulationzz.shtml
I hope I've been of some help. I respect your qualifications and your intelligent queries in prior postings, and I feel you're more than qualified to resolve this conventional heat transfer problem.
Muita sorte
RE: Insulation for -25C
Here's a star and
Muito Obrigado.
RE: Insulation for -25C
Montemayor,
You had me going for a minute thinking you were going to recommend Cork.
RE: Insulation for -25C
The only cork I employ nowadays is on my wine bottles.
But you're on the right track; I used cork in NH3 refrigeration systems. All of it was gone by the time I'd been in the plants for 15 years and I was responsible for stripping a lot of it out. Some of the young whippersnappers on the Forum are probably shaking their heads right now, wondering what in the world we're writing about.....
RE: Insulation for -25C
Unclesyd and Montemayor,
I thought you both were talking of sharing a vine
Cork insulation is new to me though it is an old technique.
Regards,
RE: Insulation for -25C
Some 30 years ago I visited a -now "extinct"- relatively small lube oil refinery in the Balkan peninsula actually using Mediterranean cork for cold insulation of its rotary vacuum filters in a solvent oil-dewaxing plant.
RE: Insulation for -25C
As to Cork Insulation: don't act so octegenarian, boys. Lots of Cold Storage Warehouses and Ice Houses right up through 1960 were insulated with Slab Cork. And there are many ice silos standing alongside rail sidings today in California and Oregon that use Red Wood Bark and in a couple of cases, dried seaweed as insulation. One building I know of was re-insulated with dried silage, that is chopped up corn stalks...
The larger difficulty: Both the binder used in making slab cork, and the installation techniques that usually involved Tar or Asphalt, were highly flammable...and the cork only net contributed to the effect. Not very long ago, we built a large High Visibility beverage vendor's showroom and the exposed surfaces were blond cork.
Insurance Companies and Corning killed cork as a commercial insulation material. I wouldn't think of it as the ideal material for pipe insaulation in the Amazon Jungle...
RE: Insulation for -25C
They make some good products such as the Peel and Stick. I definitely would give them a call.
http://www.rg2400.com/weapons/literature.html
Here is the home page of the RG 2400 manufacturer “PolyGuard”.
http://www.polyguardproducts.com/
Montemayer,
Circumstances have forced me to the lower shelves where plastic prevails.
sterl,
Agree completely with the use of Cork in this application.
Still a few ice plants along the coast that produce 300# blocks of ice the old fashion way with NH3 refrigeration and circulating brine as the freezing medium with every thing being cork insulated. Several of these plants used to sit dockside.