Hello:
This involves original plumbing from a house built in 1918 and please view photo, first, by clicking on this link,

[i.postimg.cc]

As a novice plumber my questions & approach follow:

QUESTIONS
1. Was the original connection between lead drain pipe and brass hex-nut soldered?
2. The threaded hex-nut, here, is probably a standard size but what, "exactly", would that be?
3. Would the PVC replacement parts, i.e. threaded hex-nut and drain pipe tailpiece, be purchased separately and
glued together? Or, are such 1-piece PVC connectors available?

PROCEDURE
1. SawZaw through lead drainage pipe about 2-6 inches to left of cast iron stack connector.
2. Remove hex nut, and attached length of sawed-off drain pipe, by unscrewing from stack connection.
3. Purchase new parts -- rubber fernco, PVC pipe & PVC hex nut.
4. Assemble these items into a replacement piece and adjust to fit as per length of PVC pipe needed.
5. Glue any existing PVC connections within this replacement piece.
6. Install replacement piece via (a) Screwing hex nut (at replacement piece right) into cast iron
stack connector and b) Attaching fernco (at replacement piece left) to sawed-off end of lead drain
pipe and tighten.

Thanks for your inputs.



Edited 13 times.

That doesn't look like a job for a novice. If it is your property I suggest you hire an old timer plumber. If someone wants to hire you to fix it, as a novice, your best bet is to gracefully bow out.

Thanks for your input which may, very well, be right. I’m thinking now -- it’s probably not possible to screw threaded PVC into cast iron. So, at the very least, a specialty plumbing store will, likely, be required. Calling a plumber isn’t out of the question either.

i hate to admit it but i guess you could call me an 'old time ' plumber.
i have seen a lot of lead work but i have never seen lead attached to cast iron by way of a threaded fitting.
can you tell if the threaded fitting is steel or brass?
if it is brass then the lead has worn away and i would be tempted to keep the fitting.
i would cut the lead close to the threads and very carefully melt away any more lead. at that point you may be able to fit a fernco adapter over the end and transition to plastic.
if the threaded piece is steel then it is probably rusted thru and you will have to remove it and ????
as i said , i have never seen anything like this.

Hello:

1. The hex-nut fitting must be brass because its threads have turned green, i.e. the color produced, over time, by
oxidation of copper, brass and bronze.

2. Your idea of attaching a fernco to this fitting is a great one. To do this I'd, initially, try tightening this
fernco right on the hexagon, I guess.

3. The following question regarding your post occurs though. Why would it be necessary to melt away remaining
lead, first? If the fernco is big enough to go around the hex-nut and the lead pipe, even a short
length of it left remaining, is narrower, how would it interfere?

Thanks for your comments. -They're greatly appreciated.

the 'hex nut thingy' is most likely a brass bushing (with or without a nipple inside the lead) to which the lead was soldered or 'wiped'


you will need to unscrew it from the CI and get a (M)NPT X Plastic Tube adapter of whatever type plastic you will use to repipe to a convenient spot to reattach to the lead with a 'Fernco' or repipe the branch completely


a sawzall will be your best friend on this job

==============================================

"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

i'm thinking the lead pipe is attached somehow to what ever is upstream of the hex nut?

if i'm guessing correctly there may be enough brass there to get a fernco onto. you only need 3/4 inch or so.

Hello:

Are you saying that the brass hex-nut should be removed and not used, i.e. replaced with an "(M)NPT X Plastic Tube adapter"? This would mean screwing plastic into CI. Is that possible?

Thanks so much for your comments and for the correct terminology of "sawzall".

Hi again:

The octagonal brass fitting has exactly 5/8" of exposed area with Octagon = 1/4" W & Threads = 3/8" W. Also, the threads are graduated, i.e. larger at the octagon and smaller at the CI.

Close-up view: [i.postimg.cc]

The dimensions you listed are not relevant. You would either be clamping onto a pipe stub that might be under the lead(if one is there and is in usable condition), or unscrewing the hex fitting from the tee and starting new from the tee. You will not be clamping over the hex or it's tread. A 3rd option would be to clamp over the lead, if it's internally supported to the hex fitting, and the lead is a consistent and proper diameter for a shielded coupling.