Corroded 2" Drain Pipe Under Slab

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Pkin

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I need advice about how to proceed with a plumbing problem. I finally got up the nerve to jack-hammer the slab in my basement to begin a project to move a shower drain. It now looks like that was the easy part ... when I removed the P-trap to extend the drain line, the trap snapped in two. I found severe corrosion within the first few inches downstream of the Fernco fitting that connected the 2" drain to the P-trap.

The picture shows the drain leading towards the "wet wall" under the slab. I was thinking (hoping) that the corrosion might be limited to the immediate region near where a fernco connected the pipe to the p-trap, maybe due to standing water. It sort of feels that way. So my plan is to cut it back further and see if I get lucky.

Should I just jack hammer the entire thing out and replace it, or might I get lucky? Also ... the outside of the pipe has some lumps that look like corrosion. It seems like the fernco fitting won't make a good seal. Is there some way to clean the pipe?

Thanks for your help!!!

2 inch cast iron.jpgoverview.jpg
 

Pkin

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I cut back a few more inches. The pipe is much thinner at the bottom than at the top with the start of a crack along the bottom down the axis of the pipe.

WTF ... the house is only 42 years old. Why would they build homes with buried pipe beneath the home that only lasts 40 years? Now I wonder if the entire plumbing system is in the same state.

Never buy a home with slab foundation!!!
 

Terry

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Kitchen sink pipes can go bad in 50 years if things like Draino are used. It eats away the bottom of the pipe. Also anything with acids. Lemons, Limes.

When I work commerical, it's typical that a sink in the bar will have bad drain lines. All those lemons being squeezed into the drinks.

If you put anything down the drain, it should be something safe for pipes.
 

Pkin

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Would an expert plumber just excavate everything beneath the wet wall and plan to replace everything?

The wall separates two bathrooms and there is a load of DWV plumbing connecting beneath the slab: two tubs, two showers, two sinks... and there are two vent lines and a 3" drain from the upper floor that pass through the slab at the bottom of the wet wall, presumably connecting to a 4" main drain line.
 

Dlarrivee

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I would bust out the jack hammer again.

Until you feel confident in the integrity of what you plan to tie into, you're going to have to keep removing corroded pipe.
 

Pkin

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I dug up the rest of the pipe and it was shot. The inside of the sanitary tee is corroded about 70%, but still solid.

I moved this thread to a new one "keep or replace old cast iron under slab"

2 pipe corroded on bottom.JPG
 
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