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Easiest way to deal with corroded drain pipe at floor slab?

Posted by smallsea (My Page) on
Sat, Oct 20, 07 at 22:55

Our house was originally constructed in 1957 with a mix of galvanized and cast iron for drain pipes. In 1970 the previous owner did some remodeling and used copper drain pipes. Now it's our turn to remodel...

The photo below shows the drain pipes from our bathrooms and laundry room. We believe the drain pipe under the slab is cast iron, with a cast iron hub at the floor slab. There's a copper drain pipe tying into that CI hub - you can see the corrosion where the metals meet.

Our replacement drain pipes will be PVC.

Can we cut the copper below the T, leaving a 2-inch stub of copper, and tie our PVC drain into the copper with a Fernco fitting? Or do we need to bust out part of the concrete slab and tie the PVC into the CI below the slab (so as to remove that corroded hub?)

Thanks for any advice or ideas you can provide.

Drain assembly, looking east
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Close-up of corrosion, looking east
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Close-up of corrosion, looking west
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RE: Easiest way to deal with corroded drain pipe at floor slab?

In the upper photo where the top galvanized pipe connects to the copper riser on the left there is severe corrosion on the iron pipe threads which appears as if it may be a problem, but aside from that, the corrosion on those pipes is not near as bad as one might think. The green color on the pipes is called "Patina" and it is not a problem at all. In fact, that is the same green patina that gives the statue of liberty her famous green color and in the art world it is highly sought after.

At the floor you have a cast iron pipe hub flush with the floor and the copper pipe is set into the cast hub by means of oak and poured lead.

You can cut the pipe as you describe and attach your new PVC by means of a rubber Fernco coupling or you could cut the copper pipe flush with the floor, then clean the pipe stub and lead out of the cast iron hub and connect your new PVC into the hub by means of a Fernco PVC x CI donut connector.


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