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Best tube of caulking for sealing metal duct work?

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[OP]
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Oct 17, 2010
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Best tube of caulking for sealing metal duct work?

we have commercial metal duct work thats leaking a bit of oil. It does get cleaned twice a year.

its prob not the most pernament solution but i just want to stop it for now. surface has been degreased and cleaned.

i was wondering what the best type of caulking, silicone or something else to use . iits leaking between two large pieces of duct work (the joint).

my other option was using aluminium tape
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[OP]
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Oct 17, 2010
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schade wrote: Try some Mastic.
l69norm wrote:
TomLafinsky wrote: Tremco TremPro 644 HT - high temperature silicone sealant.
i found either of these:

High Temperature Silicone Sealant

https://www.canadiantire.ca/en/pdp/impe ... 2712p.html

https://www.homehardware.ca/en/300ml-bl ... /p/2031188

does it matter. canadian tires model says 316C over homehardwares 216C. one is red other is black
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Feb 11, 2007
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thatsnazzyiphoneguy wrote: we have commercial metal duct work thats leaking a bit of oil. It does get cleaned twice a year.

its prob not the most pernament solution but i just want to stop it for now. surface has been degreased and cleaned.

i was wondering what the best type of caulking, silicone or something else to use . iits leaking between two large pieces of duct work (the joint).

my other option was using aluminium tape
Hi temp silicone would probably be best, hopefully the gap isn't too large. If it is large, them high temp spray foam gap sealer.

Oil in your HVAC duct is an odd one though.
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thatsnazzyiphoneguy wrote: we have commercial metal duct work thats leaking a bit of oil. It does get cleaned twice a year.

its prob not the most pernament solution but i just want to stop it for now. surface has been degreased and cleaned.

i was wondering what the best type of caulking, silicone or something else to use . iits leaking between two large pieces of duct work (the joint).

my other option was using aluminium tape
Why is there oil in the duct work?

If something must be done, Aluminum tape is a very good choice as it can easily be removed and reinstalled. Mastic is forever and sealant will absorb the oil and peel off.
[OP]
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TomLafinsky wrote:
Go with the one with the highest temp rating. After all, you said it was a temporary solution. Tremco is probably the highest quality among those three.
engineered wrote: Hi temp silicone would probably be best, hopefully the gap isn't too large. If it is large, them high temp spray foam gap sealer.

Oil in your HVAC duct is an odd one though.
Pete_Coach wrote: Why is there oil in the duct work?

If something must be done, Aluminum tape is a very good choice as it can easily be removed and reinstalled. Mastic is forever and sealant will absorb the oil and peel off.
thanks guys!

one of my family members has a diner and the duct work is 16 guage steel for a exhuast hood. hence oil leaking...well grease. was installed in the 80s and i guess wasnt properly sealed or something since then.

didnt want to leave you all hanging so i took most of your advice and used high temp silicone AND aluminium tape. heres what it looks like. the gaps with the red silicone is where it was welded so didnt need to cover that. not sure why whoeverr put this in never bother to WELD THE WHOLE SEAM.

do you guys think this should work? at least for a little while. there getting tired of cleaning grease off the roof.
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thatsnazzyiphoneguy wrote: thanks guys!

one of my family members has a diner and the duct work is 16 guage steel for a exhuast hood. hence oil leaking...well grease. was installed in the 80s and i guess wasnt properly sealed or something since then.

didnt want to leave you all hanging so i took most of your advice and used high temp silicone AND aluminium tape. heres what it looks like. the gaps with the red silicone is where it was welded so didnt need to cover that. not sure why whoeverr put this in never bother to WELD THE WHOLE SEAM.

do you guys think this should work? at least for a little while. there getting tired of cleaning grease off the roof.
OK, I think that would be best described as fume extractor duct work if it's above a commercial cooking surface.
It should work for a while, especially if you cleaned properly with brake cleaner or something before applying.
My main concern would be the risk of a grease fire in the duct work, but assuming it's up to safety spec I guess that's OK.
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engineered wrote: OK, I think that would be best described as fume extractor duct work if it's above a commercial cooking surface.
It should work for a while, especially if you cleaned properly with brake cleaner or something before applying.
My main concern would be the risk of a grease fire in the duct work, but assuming it's up to safety spec I guess that's OK.
the system is old, well built not properly done. for example it wasnt properly sealed in the places i caulked red.

there are NO access panels on the roof top for the duct work. only access is for the fan. it is cleaned twice a year but only around the fan area.

i was planning on using a grinder i have to cut a hole and make an acess point. but im concerned grinding a hole in the steel could possibly light the excess grease inside the duct on fire?

i tried to light some grease from the hood below on fire once. took a small sample of it and tried to light it with a lighter. it wouldnt ignite whatsever.

getting a little off topic from the original post about caulking but do you think it would be fine to grind a new access hole?
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thatsnazzyiphoneguy wrote: the system is old, well built not properly done. for example it wasnt properly sealed in the places i caulked red.

there are NO access panels on the roof top for the duct work. only access is for the fan. it is cleaned twice a year but only around the fan area.

i was planning on using a grinder i have to cut a hole and make an acess point. but im concerned grinding a hole in the steel could possibly light the excess grease inside the duct on fire?

i tried to light some grease from the hood below on fire once. took a small sample of it and tried to light it with a lighter. it wouldnt ignite whatsever.

getting a little off topic from the original post about caulking but do you think it would be fine to grind a new access hole?
Using a grinder is kind of a brute force way of making an access panel. While it is possible to do, it requires deft touch. Sheet metal is really too thin to do this to, and if the cut off disc goes slightly off 90 degrees, it will grab and break the disc and/or distort the sheet metal.
Your best bet would be to drill pilot holes then use aviation snips to cut the opening.
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MrFrugal1 wrote: Using a grinder is kind of a brute force way of making an access panel. While it is possible to do, it requires deft touch. Sheet metal is really too thin to do this to, and if the cut off disc goes slightly off 90 degrees, it will grab and break the disc and/or distort the sheet metal.
Your best bet would be to drill pilot holes then use aviation snips to cut the opening.
+1
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[OP]
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Oct 17, 2010
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MrFrugal1 wrote: Using a grinder is kind of a brute force way of making an access panel. While it is possible to do, it requires deft touch. Sheet metal is really too thin to do this to, and if the cut off disc goes slightly off 90 degrees, it will grab and break the disc and/or distort the sheet metal.
Your best bet would be to drill pilot holes then use aviation snips to cut the opening.
engineered wrote: +1
use this method even for heavy gauge steel duct work?
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thatsnazzyiphoneguy wrote: use this method even for heavy gauge steel duct work?
How heavy? They do make larger shears.
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