Density of an Insulation

How about compressing and adding 25% more insulation into the same pipe?

80/64 = 1.25 = 125% of installed insulation.

Fibreglass insulation is compressible right?

Yeah, that's the idea. Pack it as tight as possible to get more R in the box.

No problem then, unless perhaps something has to pass through said pipe.

that lowers its valuehttp://www2.owenscorning.com/literature/pdfs/10017857%20Building%20Insul%20Compressed%20R-Value%20Chart%20Tech%20Bulletin.pdf

I'm curious to know how you arrived at 64 Kg/m3 density and 3 inch thickness if you don't know how to calculate the necessary insulation required in the first place?

You want to defend an indefensible decision on your part, now that it has been questioned.

Desperation on your part does not instill urgency on ours.

Search the internet for a solution and remember this next time you take a WAG that may be questioned later.

Just had a chuckle. Went back and looked at the OP's past requests for help.

Please check the thickness as mentioned in the agreed contract technical specification . If the consultant is insisting on particular thickness he must have designed the system based on certain K value and thickness.

Fiberglass isn't particularly well suited for insulating cold pipes. Much better is expanded polystyrene or polyurethane foam, probably about 1.5 inch thickness in this case, and covered with a high-quality vapor barrier.

Too bad you are not located in New York or New Jersey: you could just hand the 'consultant' 5 $100 bills and say "are you sure? It looks fine to me"

Good idea, except I'd guess he hand the "consultant" 308749.47 Rupees.

It actually means you are cheating the right specification and not reading the contract-but you may. This literally means change the under specs installation.--that is your fault if you are not complying as per contract.

Now if it's the other way around, this is a variation order and additional labor and materials for reworks is chargeable to the owner,--which is a good thing to you, bad for the consultant and engineers(owner side).

You don't say if the new insulation is also fiberglass. The insulating value of most insulating materials is due to trapping air and preventing circulation of that air. A higher density insulation of the same material will contain more of that material and less air. If I'm not mistaken, a higher density insulation of the same material and thickness will transfer MORE heat than the lower density insulation.

To get better insulation, you need either a better material or greater thickness.

Since you are trying to keep heat OUT, a reflective coating such as aluminum foil on the outside of the existing insulation can help significantly.

That's right, you beat me to it. OP hasn't said why the consultant wants higher density, perhaps he's under the impression it will improve insulation, or some other reason.

It could also be for abrasion resistance.

Lets see if we can get to a hundred different plausible reasons before the OP comes back.

Thanks for all the reply. The specification was 80 Kg/M3 Density Fiberglass pipe insulation. The mistake had happened from the site engineer. It was my responsibility too cross check. So we are all responsible. Now it is installed and all vapor barriers like foster coatings are applied. We had realized our mistake at the time of inspection. To remove and to new installation is not feasible as the material, cost and more over we will all be responsible.

Any advice….

You still have not said whether the thickness of the installed insulation is the same as the specified thickness, nor what that value of thickness is.

If I understand correctly, you have some thickness of 64kg/m³ fiberglass insulation, while the original specification was that same thickness of 80kg/m³ fiberglass insulation.

If that is correct, then I believe that the installed insulation will provide better heat rejection than the 80kg/m³ fiberglass insulation would have provided, but it will be somewhat more susceptible to physical damage from accidental impact/force.

"Thermal conductivity of insulation 0.032 at 24 degree centigrade" 0.032 in what units?

Without knowing the thickness of the insulation and the total length of pipe, there is no way to calculate even a rough estimate of the heat gain of the cold material.

It is 3 inch thickness.What i have installed is 64Kg/m3 Density with 3 inch thickness and the specification was calling for 80 Kg/m3 Density with 3" Thickness.Thermal conductivity is 0.032 Watt per meter per celsius degree (W/m-°C).Length of each pipe is 1.2 meter.

Thank you.

Now, in my limited experience, the term 'thermal conductivity' is a property of a material, as illustrated by the following sample

(from the Physics Hypertextbook 12/8/11):

"

"

The suppliers of your fiberglass should be able to provide values of thermal conductivity for both densities. As I have stated previously, I'm almost certain that the higher density material will have a higher thermal conductivity, and thus a greater heat ingress.

I suspect that your value of 0.032 W/m-°C is a maximum permissible heat gain for the 1.2 m length of pipe. That is not a thermal conductivity. If English is not your first language, we may have had some misunderstandings due to translation...

You haven't stated what the "desired properties" are.