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BOOPATHY
Active Contributor

Join Date: Jul 2010
Posts: 18

Rusting in Paint Booth Exhaust Duct (Chimney)

12/12/2015 12:03 AM

Dear Friends,

we are bus body manufacturing industry.

We have a downdraft paint booth with water scrubber and exhaust system.

The exhaust chimney duct got rusted in 5 years time and I replaced all the ducts last year. Now within a year the ducts started rusting.

I enquired with the duct supplier he says pickling process in the area will affect the chimney ducts.

is it true that the ducts will get rusted and get damaged in such a short time.

We have used Jindal steel 1.2 mm thikness sheets.

please give your suggestions to avoid this.

Regards,

M.Boopathy
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SolarEagle
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Join Date: Mar 2007
Location: by the beach in Florida
Posts: 33321
Good Answers: 1810
#1

Re: Rusting in Paint Booth Exhaust Duct (Chimney)

12/12/2015 1:20 AM

You could go with aluminum or Stainless duct, or just coat your existing ductwork with a rust proof coating....

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spades
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Join Date: Aug 2014
Location: Port Macquarie N.S.W. Australia
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#2

Re: Rusting in Paint Booth Exhaust Duct (Chimney)

12/12/2015 1:21 AM

Your water scrubber will be putting some moisture content into the duct, and this will cause even good quality gal steel to corrode over time, especially at overlaps and raw ends.

Paint the inside of the ducting with a good quality impervious paint such as an epoxy or similar and consider using stainless or aluminium ducting next time, a bit more expensive, but you won't be replacing it so soon.
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BOOPATHY
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Join Date: Jul 2010
Posts: 18
#3
In reply to #2

Re: Rusting in Paint Booth Exhaust Duct (Chimney)

12/12/2015 1:25 AM

Does the pickling plant near by my plant affect the GI ducts in my plant?

This was told to me by my supplier. is it true? or is it a general rusting process.
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spades
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Location: Port Macquarie N.S.W. Australia
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#4
In reply to #3

Re: Rusting in Paint Booth Exhaust Duct (Chimney)

12/12/2015 1:59 AM

I would expect any corrosion occurring due to the nearby pickling plant would affect the outside areas of your ducting much more than the inside, so, if this is what is happening, then you might consider that the pickling plant may be contributing to the problem, but if it is mainly the internal surfaces of the ducting that is deteriorating, then no, the pickling plant is not to blame.

If the pickling plant was to blame there would be fairly wide spread corrosion on all of your untreated metal surfaces.

If you are concerned that the pickling products are entering the ducting from the exit ends - which could only occur when the booth exhaust is off - then consider installing automatic shutters on the stack exits.
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SolarEagle
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Join Date: Mar 2007
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#7
In reply to #3

Re: Rusting in Paint Booth Exhaust Duct (Chimney)

12/12/2015 2:34 PM

You would have to conduct some environmental testing to see if the pickling plant is off gassing in your direction....it certainly is possible...

http://www.finishing.com/164/32.shtml

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Rixter
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#5

Re: Rusting in Paint Booth Exhaust Duct (Chimney)

12/12/2015 9:19 AM

You could paint them.

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lyn
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Join Date: Oct 2008
Posts: 42376
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#6

Re: Rusting in Paint Booth Exhaust Duct (Chimney)

12/12/2015 10:56 AM

It sounds like inferior steel was used.
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texasron
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Technical Fields - Project Managers & Project Engineers - New Member

Join Date: Oct 2013
Location: Texas.Baytown
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#9
In reply to #6

Re: Rusting in Paint Booth Exhaust Duct (Chimney)

12/14/2015 7:45 AM

Uhhhh, working for the aforementioned supplier i would do a XRF PMI on the material.

Cant say anymore as it may alert the lawyers.

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Inspect1
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Join Date: Dec 2015
Posts: 1
#8

Re: Rusting in Paint Booth Exhaust Duct (Chimney)

12/13/2015 9:48 PM

It could be that the duct is not joined to it self properly make sure were it is joined at the seams there's a good fit and a solid connection. I have seen duct work rust out when the seams were not tight there was a lot of static in the air. However with a wet scrubber that should not occur?
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joeymac
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#10

Re: Rusting in Paint Booth Exhaust Duct (Chimney)

01/06/2016 3:22 PM

Your best bet would be to use aluminum or stainless steel since they won't rust or at least for a very long time. If there's moisture being trapped, then that will accelerate the rusting process with your steel. I've worked as a painter and if you paint or prime coat over something that has moisture, being it wood, metal, etc the moisture will get trapped and eventually bubble up and cause the paint or coating to fail. So if you go that route make sure there is no moisture.
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BOOPATHY
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Join Date: Jul 2010
Posts: 18
#11
In reply to #10

Re: Rusting in Paint Booth Exhaust Duct (Chimney)

01/07/2016 12:38 AM

Thank u all for your suggestions.
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Users who posted comments:

BOOPATHY (2); Inspect1 (1); joeymac (1); lyn (1); Rixter (1); SolarEagle (2); spades (2); texasron (1)

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