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Active Contributor

Join Date: Feb 2009
Posts: 11

Pre-Fab Material for High Temp Exhaust

03/26/2009 10:31 AM

I have an application where I need to provide exhaust for two gas-fired chillers. The discharge temp. is a constant 1400 deg. The problem is the connection to chiller, expansion joints, catalytic converter, ect. supplied with the chiller are all based on 4"ID. Thus far, I have not been able to locate a supplier that makes pre-fab material w/ a 4"ID for this discharge temp. Furthermore, I do not want to use 5"-6"ID and use transitional fittings as this seems like it would disrupt draft. Termination at roof is about 105L.F. rise - no exhausto fans are being used. When all is said and done it appears I will be forced to use SS pipe to meet diameter requirements, unless anybody knows of a manufacturer than can meet these requirements.

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Participant

Join Date: Mar 2009
Location: South of Brazil
Posts: 3
#1

Re: Pre-Fab Material for High Temp Exhaust

03/27/2009 7:58 AM

hi everyone!

HVAC.EST, I was thinkink about the exaust temperature, does the equipment or piping has any internal protection? Like a refractory coating?

Will SS pipes resist to that temperature without protection?

Sorry if it didn't help, i faced the same problem a few years ago and i got out of the project before this issue was solved. I'm trying to get those people im contact again to get more information now.

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Active Contributor

Join Date: Feb 2009
Posts: 11
#4
In reply to #1

Re: Pre-Fab Material for High Temp Exhaust

03/27/2009 9:20 AM

the material that was specified for this temp. range consists of 304ss inner wall, aluminized steel outer wall, with 4" factory installed thermal fiber insulation. This is a positive pressure exhaust system, however it appears no manufacturer can make this material with an ID of 4" - lowest ID available (to my knowledge) is 5". Of course I can use 4" 304/316 SS pipe with the same insulation requirements, downside is F + I cost of that option greatly outweighs that of pre-fab.

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Anonymous Poster
#2

Re: Pre-Fab Material for High Temp Exhaust

03/27/2009 8:54 AM

316ss will be a fine choice. I would isulate the pipe and take it through walls or roofing with and insulated sleeve. Be carefull about shortcuts with something like this. Produce it to be easily assembled or removed and the pipe mount will be a floater or an exansion device will connect the pipe to the chiller.

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Guru
Hobbies - DIY Welding - pipewelder

Join Date: Apr 2007
Location: North Georgia, USA
Posts: 671
Good Answers: 33
#3

Re: Pre-Fab Material for High Temp Exhaust

03/27/2009 9:19 AM

I think you should look at 310 stainless or 625 inconel material. Both are "high heat" type materials and should work allot better than 316 stainless. if you can't find the material in the size you need you can always have it rolled from plate and then welded into a pipe shape. you may also find a better match for your size by looking at buying tubing instead of pipe.

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Anonymous Poster (1); GVA_BR (1); HVAC.EST (1); pipewelder (1)

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