Repairing Rotted Galvanized Drain Pipe


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Old 04-23-24, 05:31 PM
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Repairing Rotted Galvanized Drain Pipe




This is at a cabin I'm not at currently, however relatives sent this pic since I'll be the one fixing it.

If I can, I plan on cutting this pipe and unthreading it from both ends. Replacing it with PVC by installing two sections of PVC threaded into each fitting (this 'T' and the elbow its connected to above). Then connecting the two PVC pipes with a fernco fitting. (Is this an accepted method?)

If this is not possible, do they make a fernco fitting that I can use that connects the "undamaged" galv pipe to the bell end of the galv T in had been threaded into?
 
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Old 04-23-24, 05:51 PM
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That looks like a cast iron tee.
Are you sure it's threaded.
I see the threads but it doesn't mean the tee is threaded.
Looks like it may be a galvanized pipe leaded into the tee.
See if you can get a pic of where the pipe actually goes into the tee.

Example of compression donut.
 
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Old 04-23-24, 05:54 PM
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I'd suggest you be ready to cut, pry and/or chisel out any remaining threads left inside the hub. Have a small wire wheel on a drill to clean up the threads inside the hub. Buy a short nipple the same size as your pipe and some ptfe paste and a shielded Fernco repair coupler (no hub and no stop collar inside the Fernco).

Slip the Fernco up the pipe after you cut it to length. Use a little lube or silicone grease to make it slide easier. Screw your nipple into the hub using the paste on the threads. Once it's together, slide the Fernco down and tighten it up. And if that hub and adjacent pipe is unsupported be prepared to wire it up with some pipe strap. The Fernco should not be the only thing supporting it.
 
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Old 04-23-24, 08:13 PM
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looks like a cast iron tee
Here's another pic, I'm leaning towards threads. But never knew about that donut thing. Will file away for future.



XSleeper , If I understand you correctly, I'd cut the pipe back enough to fit the nipple in and rescrew it into the fitting. Then span the space between the nipple and the old pipe with the Fernco. That empty space would be the amount I'm able to screw the nipple into the fitting?

If it's 2" pipe then use the following...

https://www.supplyhouse.com/Fernco-N...o-Hub-Coupling
 
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Old 04-23-24, 08:29 PM
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You have the right idea.

No, that Fernco has a stop collar inside it. You could use it but it won't slip up the pipe... I was thinking more along these lines.

https://www.menards.com/main/plumbin....htm?exp=false
 
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Old 04-24-24, 01:48 PM
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Got a better picture, looks like the weight of the horizontal pipe broke free and dropped an inch separating them. Anyway, I think I'll just go ahead and replace that connection with pvc by cutting back the vertical galvanized and connecting it to pvc with the shielded Fernco mentioned earlier. So should I use a wye & 45 or combo & 1/8?

https://www.homedepot.com/p/Charlott...00HD/203396237

Or use the one that fits best? Instead of the 90 to the left of the "T' I'll angle the wye/combo and use a 45 and cut the straight length of galv pipe a little further down and reconnect to the new pvc with another Fernco. Unless there is a better way?

Instead
 
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Old 04-24-24, 02:12 PM
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You've got a mess on your hands.
I'm pretty sure I'd try to remove that cast iron tee.
Trying to clean the upper threads where that pipe screwed in is going to be next to impossible.
 
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Old 04-24-24, 06:44 PM
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Yeah you could cut it above the "I" in instead and put your fernco there... then replace the rest with pvc in the same configuration that is now.
 
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Old 04-25-24, 09:58 AM
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I agree, I'd pull out as much of the galvanized as possible and replace with PVC. I'd put money on the horizontal galvanized is clogged significantly. I'd absolutely replace the horizontal galvanized up to the tee and cleanout.

If the vertical is somewhat accessible, I'd replace that too. If it's hidden behind tile or something you can't repair easily, I'd figure out how to no-hub coupler to it to a combo wye with a cleanout (the no-hub is what XSleeper provided the link to). You might need some elevation to spare to use combo wye vs the tee that's there. But a wye will help with eliminating clogs.
 
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Old 04-25-24, 05:44 PM
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I'll remove as much as possible without replumbing the whole system (for now). Along those lines....

That vertical galv that rusted through; I have access to the connection above. If I'm able to unthread it I'll need to thread a male pvc adapter on to start the downstream conversion to pvc. Is it generally accepted to do this (use male pvc to iron pipe)? I know female pvc threaded fitting can suffer from cracking if tightened too much, not sure about male threaded pvc adapters.
 
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Old 04-25-24, 07:09 PM
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That's why you use pfte paste when you put it together... it helps lubricate the threads and prevents leaks. You don't need to tighten pvc to galv as tight as humanly possible, (that's when it cracks) you have to know when to quit torquing. Drains aren't under pressure so this isn't like torquing the head on your engine.
 
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Old 05-15-24, 09:28 PM
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Well...the job got a bit bigger as each time I cut away rotted pipe, the previous threaded joint would break. I finally got back to good metal (in the wall above) and one item I will need to replace is a 4-way iron tee.




I plan on using something like this

2 in. x 2 in. x 1-1/2 in. x 1-1/2 in. PVC DWV All Hub Double Sanitary Tee


I've seen similar fittings where the side connections look to be a long sweep version. When would one use that versus this?
 
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Old 05-16-24, 02:55 AM
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See section 706.3 and table 706.3.

https://codes.iccsafe.org/s/IPC2015_...-Ch07-Sec706.3

a fixture with pumping action is one of the reasons for long sweeps.
 
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Old 05-16-24, 08:50 PM
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Thanks. Reading that and referencing my AHJ looks like the one I pictured is allowed. Will be back in a week or so with all the correct fittings (hopefully).
 
 

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