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I have sewer pipe (110mm, underground) containing telephone wires, etc, to a shed in the garden. I need to disconnect a joint to put a piece of tubing through as well. Is there a good way to disconnect the joint without actually destroying it, in order to pull some flexible plastic tubing through? The joint has been there several years, and it's difficult to get a rubber mallet behind it, to persuade it off the same way it was connected. It's not solvent welded, or simply a push in without solvent, but has a rubber gasket to seal from leaks.

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    Without a pic it's gonna be hard give you good ideas...
    – Huesmann
    Commented Jan 11 at 12:41
  • "Sewer pipe" as in this is actually part of your plumbing system carrying raw sewage from your house to the city sewer system, or is it just a section plumbing pipe being repurposed as a specifically installed electrical conduit (which is against code in the US and likely other countries as well) and is in no way connected to the plumbing system?
    – FreeMan
    Commented Jan 11 at 13:12
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    Not preaching, just trying to get clarification since you've only provided text, not pics.
    – FreeMan
    Commented Jan 11 at 13:50
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    Is there a good way to ... pull some flexible plastic tubing through? String and a vacuum, to pull a fish tape, then pull the thing with the tape. If it can't navigate the elbows then they need to come off anyway and can't go back on. - Why are you trying at this joint instead of at both terminations?
    – Mazura
    Commented Jan 11 at 15:18
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    I want to add a compressed airline. Some air lines are a lot more supple than others.... Google blue air line. If you can't get that in there then nothing's going to go. They do like to break if you're the slightest bit mean to them though. And their fittings always start to leak.
    – Mazura
    Commented Jan 11 at 15:41

1 Answer 1

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Your pipe sounds similar to the SDR-35 4 inch sewer pipe I'm familiar with on the North America side of the pond. The bad news is that it can be difficult to separate those gasket joints. The gaskets have a lip which is oriented so that pipe insertion is easy, but when one tries to pull the pipe back out, friction draws the lip in so that it grips the pipe even tighter.

Wiggling and twisting both help to work the pipe out of the fitting, but while those movements help on a cleanout riser or a loose piece on the ground, they're not practical on a section that's partially buried.

The gaskets do allow movement of several degrees, but even so, you'll probably need to expose two meters or more of the pipe on the side that you're not disconnecting in order to have any hope of bending it. This large-diameter stuff doesn't bend easily.

A lever will probably be necessary both to overcome the gasket friction and to bend the pipe. Because lever force is steady it'll likely work better than a mallet.

Here's a useful trick for coaxing something out against the direction of the gasket lip. Insert a thin piece of stock, like a feeler gauge or a section cut from the wall of a plastic beverage container, alongside the pipe so that it passes the gasket. While applying force pulling the pipe and fitting apart, work the stock around the circumference of the pipe. This will release the friction grip of the gasket. You could experiment with using multiple pieces, or even a complete collar going all the way around the pipe. The more relief you can create between pipe and gasket the better, but don't insert so much material that the pipe ends up wedged tightly in place.

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