Formula for piping insulation thicknesses? 2

[reichertc]

Hi there. This is probably a fairly straight forward question for the members of this group, but my heat transfer textbook is on the other side of North America and I haven't done one of these problems since university.

I want to calculate the required thickness of insulation on piping to prevent the aluminum cladding from reaching a temperature greater than 140°F. (ie. for personal protection.) For ease of calculation, let's assume that the exterior surface of the piping is the same as my normal fluid operating temperature of 900°F. Calcium silicate insulation, ambient temperature of 70°F, no wind, 24" pipe.

Can anyone throw forward the formula I need to calculate the required thickness, as well as the other data I need to get information on? Any assumptions I need to make in this calculation?

Thanks in advance.

 

[butelja]

Try the following link:

http://www.pipeinsulation.org/pdfs/tech.add.pdf

Look in section 3, which has the relevant heat transfer equations. The 3E plus program is a free download from that website, and is a great tool for insulation design.

 

[PacificSteve]

http://www.foamglasinsulation.com/ear.html

Check this link, looks likethey will do the analysis for you, for the personal protection aspect.

Surface temp of 140 sounds rather high in terms of cost of energy lost...perhaps you want to get rid of this heat anyway? If not, a thicker insulation could be warranted based on economics.

aloha

pacific steve

 

[rusman]

Friends

Generally, API RP 14E gives some recommendation insulation thickness for the personal protection (temp more than 65 Deg C?). It does depend on the line size and the temperature.

Hope this help.

Rusman
rusman6800@yahoo.com

 

[jehar]

The ASTM C680 Specification, has all the formulas explained along with a computer program listing to do the calculations. This document may be viewed at

http://www.HRSGdesign.com

or obtained from

http://www.ASTM.org.

The HRSG design site also includes JavaScript calculators that will do these calculations for you. The HRSGdesign site is an educational, non-comercial, free web-site.