Corroded slip nut in wall

Old 09-17-13, 01:19 PM
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Corroded slip nut in wall

I have a vintage 1954 bathroom. I am replacing the pop-up drain assembly in the sink and the trap arm broke when I was removing the p-trap. The slip nut that connected the trap arm to the cast iron drain pipe fitting in the wall is corroded and just inside the plane of the wall. I can't afford to break any tiles, as they cannot be found today. I have applied WD40 a few times over the course of a couple hours, included using a small piece of wood to try to divert the WD40 onto the threads behind the slip nut, but I can't get a grip on the slip nut. I am letting it sit overnight to try again tomorrow, but would welcome any advice.

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Old 09-17-13, 01:27 PM
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You could try cutting the slip nut in two places with a small hack saw blade... Dont cut into the threads or you could have a leak when you down the road...

Last resort is cut tile.... is this under a vanity or a pedestal sink?

You could always go from behind if there is a wall... You can cut that whole sanitary tee out and replace with PVC...

Thats all I got for ya!!!!!
Old 09-17-13, 01:30 PM
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WD40 is a poor product for breaking loose corroded fasteners. Liquid Wrench or PB Blaster would be better.

Pro's may have other suggestions, but I'd probably use a one hand hacksaw and partially cut the nut then split it.
Old 09-17-13, 01:42 PM
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I'd use a Dremel and a carbide disk. . Probably take more than one of the cheap discs.
Old 09-17-13, 03:52 PM
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First thing I would do is collapse the brass tube inside and pull it out with pliers. Then you can get a puddle of PB Blaster right inside the nut. To unscrew it, or try to anyway, tap a sharp chisel to bite into the nut and keep tapping in a counter clockwise direction. If the pipe in the wall is solid in place, you may get lucky. This is the reason I always put teflon tape on plumbing threads that don't really need it.
Old 09-17-13, 06:31 PM
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Maybe a tightspot wrench from Superior Tools and available thru Sears. Looks like it may work.

Superior Tool 1-1/2" Tightspot" Wrench - Tools - Plumbing Tools - Pipe Wrenches & Pliers
Old 09-17-13, 08:16 PM
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Bet your going to end up opening up the wall.
It was installed way to close to the wall.
Old 09-18-13, 12:28 PM
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And the winner is!

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After I got the brass tube backed up like this, I used the Dremel wire wheel brush around the inside. When I put the pliers on the slip nut, it moved easily from all the WD40 I applied yesterday and the Liquid Wrench I have been using today. Now I have to finish prying out the rest of the old trap arm, which is totally corroded to the inside of the cast iron pipe.
Old 09-22-13, 08:21 AM
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Glad you got this done. We have used Kroil for years to loosen rusted items. The Coast Guard uses it all the time. It is Kano Laboratories Aero Kroil Penetrating Oil. The stuff is expensive but worth its weight in gold! It works on nuts, pipes, plumbing, old cars, etc. and is many times better than Liquid Wrench. We have never had something that did not come apart after soaking with Kroil. It may take a few days to loosen...eventually everything will come apart. I always have a can on hand.

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