'Ungluing' pvc dwv pipe?

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bmead144

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Does anyone know of any product made to "unglue" solvent welded connections in pvc,cpvc & dwv pipes or if there even exists such a thing?Also whats the minimum horizontal drop/slope per foot for 3" dwv pipe?
 

Gary Swart

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The answer to taking PVC connections apart is in your question. These are not glued joints, they are solvent welded. The so-called glue causes the surfaces of the pipe and fitting to soften briefly, mix together, and when the solvent evaporates, the parts are fused together. There is no way to reverse the process, and at the price of fittings and pipe, it isn't worth the time and effort to try to do it anyway. All drains regardless of size or material require 1/4" per foot or more slope.
 

Clayton

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Which Code?

Minimum slope of 3" horizontal drain will depend on which code is enforced in your area.

The IPC and the IRC allow 1/8" per foot slope on 3" with 36 drainage fixture units or less.
 

Gary Swart

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I won't say BS to your device, but I will say I am highly doubtful that you can "unglue" a solvent welded PVC, ABS, or CPVC joint. The process of solvent welding melts the surfaces of both the pipe and the fitting and these mix or flow together when the joint is made and effectively make the weld.
 

LLigetfa

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1/4" per foot is the minimum, there is no maximum.
I am not a plumber but I did all my own plumbing when I built my house. ISTR the inspector mentioning that there was an ideal slope, that too much slope would separate the solid from the liquid. It might be a regional thing and/or fluid dynamics work different this far North.
 

Jimbo

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The idea that the solids will get left behind is a widespread fairy tale, which all plumbing codes debunk.
 

Travis Griffith

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Gluing PVC does not create any kind of weld. The above comment is true, there is a device that can "unglue" pvc and other plastic pipe. Here's a video of it working:
There's one for pipe up to 12" too.
 

Travis Griffith

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I won't say BS to your device, but I will say I am highly doubtful that you can "unglue" a solvent welded PVC, ABS, or CPVC joint. The process of solvent welding melts the surfaces of both the pipe and the fitting and these mix or flow together when the joint is made and effectively make the weld.
 

Bluebinky

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Anyone seen a steel weld break due to someone using a crappy rod? Even a fusion weld (e.g. spot weld) can weaken the material around the weld, or a weld can be stronger than the surrounding material causing a failure point.

Having made the mistake of burying PVC directly in Texas clay and having "perfectly" primed and solvent welded joints cleanly pop makes me at least willing to question the "uniformly fused joint" idea...
 

FullySprinklered

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I've taken quite a few pvc joints apart. I failed often early on, but it's doable most of the time. You've got "solvent welded" joints which are permanent when done right. Then you've got your "stuck pretty good" joints which can be peeled with a little know-how and a large amount of patience. The SPG joints seem to be more common. ABS is usually more difficult to peel. I am referring to dwv here. And forget CPVC.
 

Koa

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I've taken apart both PVC and ABS fittings. It does depend on your access and what else is attached. I recently took two ABS trap adaptors off since they had developed small cracks. Depending upon if they are internal or external I used a hack saw blade to cut small sections one at a time parallel to the fitting about 1/4" apart and then use a 1/4" chisel or small screwdriver to pop out the section working my way around the pipe/fitting. Scrape the joint clean and sand a bit and you're ready to glue another fitting. It takes a bit of time but might be worth a shot if you are going to replace the pipe anyway. In my case the drain pipe was right against the wall with just the fitting exposed so I had no access.
 
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