Connecting new kitchen drain to old drain stack

[st.bear]

I am trying to hook up a new sink to this olde drain stack. It is not a standard size (1.75" I.D. / 2.75" O.D.) and I have gotten nowhere trying to find a donut that will work. Also, a boot might be a possibility, but again...weird size, plus the collar around might make that option insecure.

Any recommendations for solutions on how to adapt this would be appreciated.
Preferably without replacing the cast iron piece, as that looks like it'll be difficult to do
without knocking out wall.

 

[Reach4]

What I think you have there is a 1.5 inch NPT thread. Very standard size.

See https://terrylove.com/forums/index.php?threads/cast-iron-lav-rough-in-tapped-santee-or-not.92724/ for a discussion, but the 1-1/4 inch trap is not an option. So that copper trap adapter is probably your best option. I would use both tape and pipe dope to seal well without your having to apply a lot of torque.

https://www.menards.com/main/plumbi...oint-trap-adapter/h033000/p-1444449178264.htm
I would use a 1.5 inch plastic slip joint trap into there, but chrome-plated brass is an option that might look fancier. For experimenting before ordering, you could use a cheap galvanized or steel nipple or plug for sizing. You could also try a plastic 1-1/2 inch plug for size.

Looks like you might have a saw kerf in the thread. Hope the dope fills that up. You might want to inspect the threads around that kerf to see if they need cleaning up a tad.

 

[Sponsor]

 

[st.bear]

Thank you --that is helpful.

The saw kerfs are from removing the old pipe, which the previous owners had just sheared off before walling over it. Hoping that can be filled in without too much drama.

 

[Terry]

A standard 1-1/2" pipe nipple fits there. Also standard for a tubular trap to the nipple with slip joint nut and slip joint washer.

 

[st.bear]

A standard 1-1/2" pipe nipple fits there. Also standard for a tubular trap to the nipple with slip joint nut and slip joint washer.

Now that I have a better idea of how these are measured, it'll be much easier. Thanks!

 

[wwhitney]

Is it really possible to seal a saw kerf like that? I would expect it to be impossible, but I've never tried.

What's the condition of the metal drain below the tee? It's often best to replace galvanized drains, I believe, because by now they are likely approaching their end of life.

You have the option to cut the galvanized pipe above and below the tee, and use two banded rubber couplings to adapt to new plastic DWV.

Cheers, Wayne

 

[Reach4]

What's the condition of the metal drain below the tee? It's often best to replace galvanized drains, I believe, because by now they are likely approaching their end of life.

You have the option to cut the galvanized pipe above and below the tee, and use two banded rubber couplings to adapt to new plastic DWV.

I would try without replacing the santee, but if I did decide to cut the galvanized, I would probably switch to PVC all of the way into the basement.

 

[Jeff H Young]

Wrap it with ptfe and dope it up I think it'll work fine. As terry said just ordinary 1-1/2 pipe thread. Plumbing pipe is odd ball stuff if you haven't worked with it . Inspect it when done and as always keep an eye on it but it looks ok