'Ungluing' pvc dwv pipe?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by bmead144, Apr 29, 2005.

  1. bmead144

    bmead144 New Member

    Joined:
    Apr 29, 2005
    Location:
    Tennessee
    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?
     
  2. hj

    hj Moderator & Master Plumber Staff Member

    Joined:
    Aug 31, 2004
    Occupation:
    Plumber
    Location:
    Cave Creek, Arizona
    pvc

    No way to take glued joints apart. 1/4" per foot is the minimum, there is no maximum.
     
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  4. Gary Swart

    Gary Swart In the Trades

    Joined:
    Sep 1, 2004
    Location:
    Yakima WA
    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.
     
  5. Clayton

    Clayton Plumber

    Joined:
    Sep 26, 2004
    Occupation:
    Plumber
    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.
     
  6. phinncraft

    phinncraft New Member

    Joined:
    Feb 19, 2011
    Location:
    Spokane, WA
    hi i have a tool that will unglue any pvc ,abs,cpvc , pipe .it is made by debonding systems spokane wa
     
  7. Gary Swart

    Gary Swart In the Trades

    Joined:
    Sep 1, 2004
    Location:
    Yakima WA
    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.
     
  8. LLigetfa

    LLigetfa DIYer, not in the trades

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    Feb 6, 2011
    Occupation:
    Retired
    Location:
    NW Ontario, Canada
    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.
     
  9. jimbo

    jimbo Plumber

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    Aug 31, 2004
    Location:
    San Diego, CA
    The idea that the solids will get left behind is a widespread fairy tale, which all plumbing codes debunk.
     
  10. Travis Griffith

    Travis Griffith New Member

    Joined:
    Nov 1, 2014
    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.
     
  11. Travis Griffith

    Travis Griffith New Member

    Joined:
    Nov 1, 2014
     
  12. bluebinky

    bluebinky Member

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    Aug 31, 2011
    Occupation:
    Electrical/Embedded Software Engineer, Retired
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    Des Moines, WA
    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...
     
  13. fullysprinklered

    fullysprinklered In the Trades

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    Jun 15, 2014
    Occupation:
    self-employed plumber-electrician doing residentia
    Location:
    Georgia
    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.
     
  14. koa

    koa In the Trades

    Joined:
    Apr 12, 2005
    Location:
    Honolulu, Hawaii
    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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