Conecting ABS to Cast Iron

sbjmgJuly 29, 2010

I have a 2" drain pipe under my sink. It comes out too far (4" long piece). I have no room for the disposal. It is made of cast iron (I assume) and is threaded on both ends. I tried removing it and could not I used a large pipe wrench and a metal mallet it wont budge. The house is from 62 and I am sure the pipe is as well.

So my new plan is to sawzall the pipe down to an inch stub and place an abs piece that slips over the metal pipe and is threaded on the other end. From there I can install the rest of the ABS and the P Trap and such.

My question is how do I connect from the metal to the plastic? ABS Glue? Plumber's Dope?

Any problems you guys foresee? The original plan was to use that same adapter piece but in reverse, screw the threaded side in to the wall and stick in abs on the other end. If somehow I do this again what do I use to connect the plastic to the metal.


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The drain pipe is undoubtedly galvanized steel, not cast iron. A pipe wrench with an extension on the handle works better than a hammer in persuading the pipe to turn.
The adapter to use is called a 'Fernco' which is a short rubber connector with screw-type clamps at either end.

    Bookmark   July 29, 2010 at 2:19PM
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OK, I got the pipe off. Now I want to screw in the ABS piece which is threaded on one end and is a Female on the other so I can stick in any futher ABS to make my connections.

My question is what do I use on the threads as it is ABS onto metal. And the metal I am sure is pretty dirty.

Should I just use Plumber's Dope or should I use lots of Teflon Tape?


    Bookmark   July 29, 2010 at 3:32PM
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Clean the female threads as best as possible. A toothbrush wet with liquid wrench will help. A brass bristled brush will work better.
Two to four wraps of teflon tape should do the job.

    Bookmark   July 29, 2010 at 7:02PM
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