Insulation of piping 1

[rocio74]

Hello all,

I have to calculate the insulation thickness for a carbon steel (A 106 Gr.B) pipe of 4" sch.40, whose conditions are:

- temperature exterior: - 15ºC
- temperature interior (liquid inside pipe): 20ºC

How can I calculate this thickness? I am considering as insulation material, the polyethylene reinforced with fiber glass.

On the other hand, I found the ASTM-F 683 rule to calculate the insulation thickness however I don´t have this rule. Where can I get it free?


Thank you very much,
Rocio

 

[SJones]

http://www.pipeinsulation.org

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[BigInch]

ASTM isn't in the habit of giving their specs away for free.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[sentjoh]

Heat transfer calculation can be made by any supplier/manufacturer. In general they use their own software. I don’t know any manufacturer for “polyethylene reinforced with fiber glass”. Is it by the way a industrial environment. You might consider a material with good fire properties. Foamglass or PIR. Some other question needed to answered. Is it in-or outside wind play a role in determining thickness. What kind of insulation finish you are looking at? Determines the radiation coefficient. With these temperature CUI (Corrosion Under Insulation) can also be an issue. Did you thought about this also?

 

[LSThill]

http://www.pip.org

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INEG1000 - Insulation Design Guide

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INEG2000 - Guidelines for Use of Insulation Practices

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Insulation - Removable/Reusable

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L S THILL

 

[wlglass]

What are you trying to accomplish with the insulation? Freeze protection? Personell safety? Reduced BTU loss? Frost free exterior skin?
The insulation industry uses the 3Eplus program to calculate insulation needed for various applications. I'll bet you'll need betwee 2" and 2-1/2" of a urethane foam k=.14 to get all of these qualities. However most of us in the pre-insulated pipe industry use foams that will not meet the 25/50 smoke fire rating in a building. You can order 40' pipe for applications below ground, in non-return air spaces below a building, on a roof top or in a industrial site on racks. Just get a good jacket over the foam, like 100 mils of HDPE extruded over the spray applied 2 lb density closed cell foam. There are several manufacturers in the industry.

 

[rocio74]

What I am trying to accomplish with the insulation is that the fluid inside the pipe (water in my case) doesn´t freeze when the temperature exterior is under -15ºC. I have to insulate a tank in these same conditions too.

The insulation type considered "polyethylene reinforced with fiber glass" was recommended by a supplier but maybe it is not the better solution. In that case, what kind of insulation can I use?


Thank you very much,
Rocio

 

[sentjoh]

Insulation against freezing can’t be accomplished by only installing insulation. Unless you cover this proceswise by ensuring a constant flow, because if it stand still it will eventually freeze. More common practice is to install some king of tracing, in your case probably heattracing.

http://www.bartec.us

Given the temperatures a 50mm thick mineral wool would do the job. I assume your exterior temperature will also be over 0ºC. This means a risk of condensation in the mineral wool. I advice you install some kind of drainage.

http://www.temati.com/pmu-drainplug.aspx

and pay extra attention to the finish.

 

[wlglass]

Closed cell urethane is one of the best insulations for this purpose with a k=.14 or R=7/in. It will resist water infiltration thru condensation or jacket compromise. If the pipe is buried, most engineers would specifiy that it be pre-insulated in a water proof insulation jacket and the world class jacket is HDPE extruded over spray foam insulation applied directly to the pipe at the factory. There are two companies in the US who use this European method for manufacture of such pipe system. You can get the fittings pre-insulated or field insulate them with fitting insulation kits available from the manufactures. Coupling insulation kits cover your weld joints.

The alternate method of injecting foam into the space between pipe and rigid jacket often leaves voids with compromised insulation and icing over the pipe.
The 3Eplus program can calculate the skin temperature to prevent icing. And sentjoh is so right, there is not enough insulation in Texas to prevent freezing in standing water after a period of time. I often describe how long before the freezing begins using a spread sheet I've set up to calculate insulation thickness in various temperature scenerios should the flow in a pipe system fail (like the ice storm knocked out the power to the pumps, how long do I have to get there and drain the system or restore circulation). Attached is an excel spread sheet I prepared for insulation analysis. One worksheet performs this freeze protection analysis.

 

[rconner]

fyi

http://www.eng-tips.com/viewthread.cfm?qid=217830