I have a house built in 1958 and I'm replacing the bathroom vanity and sink with an IKEA unit that needs plumbing close to the wall. I have a new P trap, but cannot take this old P trap off. It appears to thread directly into a cast iron T inside the wall. It is not a compression fitting like I first thought. I have applied some PB Plaster and tried to unthread it, but it is just getting crushed.

My other option is to cut it off, and try to work with what is sticking out, but it got beat up trying to unscrew it.

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Close up of the T, it is one cast part:

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  • Can yo access the other end of the cast iron pipe (such as in the basement)? Might be easier to replace it all from that point on. – DA01 Feb 17 '15 at 21:37

I have never seen a P-trap with threads like you have here. If the metal is still as thin as any other P-trap out there, you may be able to drive something like a chisel down into the pipe length-wise, not to cut it but to crush the pipe down so it folds the threaded section down into the interior diameter of the P-trap, pretty much allowing the threads to disengage the interior of the cast iron. Be careful on this the cast iron is durable and can take some abuse as long as the chisel doesn't hit it directly. What you need to be wary of is the movement the cast iron does while striking the P-trap. The joints are poured lead on the fitting and a little movement may make them leak.


Hi thanks for the answers, apparently I didn't have notifications on so just saw them now.

Apparently it was not threaded on. I found this out when I broke it off trying to unscrew it. After some searching online on what I was dealing with, it was a chrome plated brass part that was soldered with lead to a cast iron hub. I found some ways to get the lead out and then put a donut in to transition to ABS but it seemed like a lot of hacking.

As stated above, the best way seemed to open the wall and replace the whole section with ABS. So I chickened out and hired a plumber to do just that. After seeing him do it, and my wallet empty out, I think it would have been pretty manageable to do, had I not chickened out.

Here is before: enter image description here

And here is after: enter image description here

Thanks your help.


I had the exact same set up. I yanked out the old chrome pipe and was left with the old lead solder. It was a silver colored ring that was about a quarter inch thick. A propane torch wouldn't melt the solder. So I then drilled a few holes in the solder and knocked out the lead solder ring with a small chisel and rubber mallet. The iron hub was threaded and accepted a 1 1/2 inch iron pipe.


I see that the plumber came in and cut open the wall and added a rubber coupler (sometimes know by the brand Fernco) on both ends. Something to consider in the future would be cutting the part in the wall off in the middle and attaching the rubber coupler there. You can then transition to PVC if you so desire. I've had to do this for some of my chrome P-traps that have shattered when I try to get into the trap itself to clear a clog.

Below, I just bought a PVC P-Trap kit and rubber coupler. A little hacksaw work and it runs great (I didn't even have to replace the vertical drain pipe). Best of all, it's hand-tight now so cleaning the trap is easy.

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