Redoing my dust collection pipes

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Forum topic by scottfl posted 08-16-2017 10:48 PM 1189 views 0 times favorited 19 replies Add to Favorites Watch
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11 posts in 1466 days

08-16-2017 10:48 PM

Topic tags/keywords: dust collection

About a year ago I set up my permanent ( or so I thought) dust collection with a clearvue and 6” pvc pipe. I connected the pipes by putting a bead of silicon caulk on the male end before inserting it into the female end. I now need to change the layout of the pipes. I am stumped as to how to weaken the caulk so I can remove the pipes. I’d really like to avoid cutting the joints away and starting from scratch. Ideas, suggestions?

19 replies so far

View Redoak49's profile (online now)


4731 posts in 2760 days

#1 posted 08-16-2017 11:48 PM

I can not help you but that is the reason I used Gorilla Tape.

View fivecodys's profile


1637 posts in 2408 days

#2 posted 08-16-2017 11:52 PM

Maybe a heat gun to soften the joint?
That is really a tough one.

-- A bad day woodworking is still better than a good day working.

View jmos's profile


917 posts in 3141 days

#3 posted 08-17-2017 12:14 AM

I wish I had a solution for you, but I think cutting my be your only bet. I’ll second Chem, heat may work.

My system is thin walled 6” PVC (ASTM-2729?) and I put in a couple of self tapping screws at each joint. The joints are really tight and it’s easy to reconfigure when needed. Just a thought for the reassembly.

Good luck!

-- John

View JBrow's profile


1368 posts in 1691 days

#4 posted 08-17-2017 12:41 AM


Since I have not dealt with the problem of disabling a joint held together with silicone caulk, I can only guess as to how to disengage the fitting from the pipe. But it would probably be faster and easier to cut out the section(s) of pipe that have to be relocated. A few straight couplings could then be bought to patch things back together.

When re-assembling the duct work, using tape as suggested by Redoak49, would provide an effective yet reversible seal. I used HVAC metal foil tape on my system and it continues doing a good job.

If committed to dissembling the joints, here are the approaches I could come up with:

There appear to be commercial solvents that claim to render silicone removable, but before buying any of these solvent, experimenting with some vinegar might work. From the odor given off when applying silicone caulk, I suspect that acetic acid (vinegar) is the carrier solvent. I have observed that silicone caulk is cured when no odor of vinegar remains. Perhaps allowing the vinegar to soak into the silicone would re-soften the silicone.

Some commercial silicone caulk removing chemicals are available. I suspect these are designed for tube and tile applications, although a couple of products may work for your application. I am not sure what, if any, affect these commercial solvents would have on PVC. These are found solvents at…

One problem with the chemical approach is ensuring the solvent is in constant contact with the silicone. Pipe in the horizontal position mounted to a ceiling makes this a challenge. Perhaps loading a glue syringe with solvent and the directing the syringe into the joint would work. Once injected, a dam of some sort may be needed to keep the solvent from flowing out of the joint. Some plumbers putty might work for this.

If the joint is secured with a single bead of silicone, perhaps the silicone bond could be broken mechanically. A hack saw blade may be thin enough to work into the joint and then a sawing action could break the bond. If the joint is too tight to work a hack saw blade into the joint, then the perhaps the PVC pipe could be soften with a heat gun so that the hack saw blade can make entry. However, the PVC connection will likely need to remain warm as the silicone is cut.

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Fred Hargis

6240 posts in 3265 days

#5 posted 08-17-2017 11:38 AM

I’ve always used silicone to seal my joints (2729), and I’ve completely removed and reinstalled my system twice…and it’s currently completely disassembled waiting for my shop to be finished (we moved again) so I can re-install it there. But I’ve never put the silicone internal to the joint, it was always around the seam on the OD. That said, I’ve always been able to separate the joints with maybe a few exceptions. But then I always had the parts dismounted and laying on the floor. I think you need to flex the joint back and forth slightly to break the adhesion of the silicone, then pull them apart. It’s not always easy, but (in my experience) it’s usually works. Then I use a razor scraper to remove the left over caulk from the pipe before reassembly. On the shorter sub assemblies, it helps to have something to secure one end, like a workmate. Strap wrenches are also good for rotating the parts to break the adhesion.

-- Our village hasn't lost it's idiot, he was elected to congress.

View Blindhog's profile


157 posts in 1820 days

#6 posted 08-17-2017 12:31 PM

I have the same system and did not use any tape/adhesive on the joints. Testing each joint with smoke and no leaks. The system has been in place for nearly three years without any problems. I know this does not help your current situation, but a thought for your future retrofit.

-- Don't let perfection get in the way of plenty good enough

View Robert's profile


3742 posts in 2252 days

#7 posted 08-17-2017 01:20 PM

I think you can break it loose.

I would try a band wrench and see if you can break it loose by rotation. A piece of rubber or sandpaper will improve grip.

-- Everything is a prototype thats why its one of a kind!!

View GR8HUNTER's profile


7547 posts in 1484 days

#8 posted 08-17-2017 01:36 PM

Fred and rwe have the answer for you FORCE them apart….. GOOD LUCK :<))

-- Tony---- Reinholds,Pa.------ REMEMBER TO ALWAYS HAVE FUN

View Redsoxfan's profile


38 posts in 2398 days

#9 posted 08-17-2017 02:09 PM

get yourself two strap wrenches and apply opposing torque. you’ll bust the caulk seal.

then, as indicated above, either use tape (my method) or caulk the outer end of the fitting.

-- Brian, Western MA

View splintergroup's profile


3778 posts in 1994 days

#10 posted 08-17-2017 02:16 PM

I’m in the “force” camp. My 6” PVC pipes are (were) siliconed together and it took two band wrenches and some back/forth jiggling to break the seal. Silicon does not stick very well to PVC thankfully.

Be careful of using any solvents as they may also attack the PVC and further “weld” it. Solvents can be useful however as a way to lubricate the joint before applying the band wrenches. I’d consider mineral spirits applied with a syringe around the perimeter of the joint, the capillary action should take care of the rest.

Now I just dry fit the joints and use aluminum tape to seal things up.

View TungOil's profile


1382 posts in 1266 days

#11 posted 08-17-2017 03:44 PM

My metal ductwork is all sealed with silicone inside the joint. It comes apart easily with some twisting when necessary. My old system was PVC and I found the joints to be so tight as to not need any sealant.

I also agree with not using a solvent, but more from a safety perspective. Depending on the solvent used you may inadvertently create an explosion hazard if the fumes are allowed to concentrate in the piping somehow.

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

View jonah's profile


2119 posts in 4070 days

#12 posted 08-17-2017 03:50 PM

Side question: why do people use PVC instead of metal ductwork?

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6153 posts in 3585 days

#13 posted 08-17-2017 04:35 PM

I did the same thing, although it was duct mastic. At first I was destroying the pipe to get it apart. Then I used a propane forced air heater to warm the joints and they all popped loose. It wasn’t easy, but with heat it may be possible.

Now I use only rivets and aluminum foil tape to assemble my duct work.
Good luck with your project.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View RobS888's profile


2829 posts in 2616 days

#14 posted 08-17-2017 04:42 PM

Side question: why do people use PVC instead of metal ductwork?

- jonah

Ease of use,

-- I always knew gun nuts where afraid of something, just never thought popcorn was on the list.

View Bill Berklich's profile

Bill Berklich

1108 posts in 1160 days

#15 posted 08-17-2017 05:16 PM

If it is on the inside mating surfaces you are pretty much out of luck. Even if it didn’t “glue” it together the adhesion on the surfaces will make separation problematic (think silicone router mat). Once you’ve cut the pipe free of the fittings you can (maybe) recover the fittings by cutting inside longitudinally and then collapsing the female portion. Good luck

-- Bill - Rochester MI

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