Connecting into old cast iron hub - help!

[StephK]

Hello plumbing friends - It's been a few years but i'm back in search of some of your excellent plumbing advice.

Renovating our old 1907 home and need to remove a bunch of junk all the way back to the vertical stack. I've attached a photo here of the problem child. You will see that the elbow heading into the stack is mostly bad. There are 2 other pipes coming into that 90, so I'd like to get rid of the whole thing.

I have two options:
1. Cut this elbow about two inches from the connection. That will leave some good cast, but not sure it's enough to connect to. Plus, it's going to be very hard to get a cutter up there. Could possibly cut back 3 or 4 inches, but this is a 90, so then i'm getting into the bend. Use fernco to connect to little stub.

2. Cut this 90 out, then chip away at the iron/oakum to clean up the connection.

If I have to do #2, how do I connect to the cast fitting? The fitting is 17.75" circumference. Can't quite figure the diameter with all that pipe in the way.

What to do?
Thanks in advance,
Steph

 

[Reach4]

The fitting is 17.75" circumference. Can't quite figure the diameter with all that pipe in the way.

That would be 5.65 for the OD of the hub, so I suspect that hub is for 4 inch cast iron.

 

[Sponsor]

 

[Jadnashua]

If you're planning new cast, then remove the pipe from the hub and lead in a new piece. If there's not enough solid length of pipe, then you'll have to remove that CI from the hub. If you don't want to use CI, then use a properly sized donut, and slide in pvc or abs pipe to it. https://www.fernco.com/plumbing/donuts-o-rings/donuts

 

[StephK]

Thank you for the tips. So nobody said "Yikes you don't want to do that yourself!!", so that's good! I've never used a donut before, so thank you for the link, our local place doesn't have them (Yes, I'm connecting 2 or 3" PVC, so will need that). I think i'll shoot for the #1 option, but if that fails, I know i have #2 in the backup.

 

[StephK]

Ugh, this donut thing is impossible. I ordered a 4x2 donut to fit in my 4” cast iron hub and that thing aint going in there. It’s very tight location and impossible to really pound on it. I don’t know if I’m just not able to get a good pound, or is this donut too large. My question is, how tight are these things supposed to be? Is it supposed to fit in easily up to the first rib?

I tried the soap thing, and even a ‘special’ lubricant. But when I hit on one side, the other pops out. Should it slide in easily to that first rib?

 

[Reach4]

Ugh, this donut thing is impossible. I ordered a 4x2 donut to fit in my 4” cast iron hub and that thing aint going in there.

Is your hub ID 4.94 inches?

 

[StephK]

Is your hub ID 4.94 inches?

ID = 4.75

 

[James Henry]

Grease both the hub and doughnut, lay a short 2"x4" on the flat against it and hit it with a 2lb. hammer if you have one.

 

[Reach4]

https://www.charlottepipe.com/Documents/DimensionalCatalogs/Cast_Iron_Pipe_Fittings_Eng.pdf page 52 shows dimension A as 4.94.

ID = 4.75

I think you or your supplier will have to contact Fernco to get the right donut. Measure precisely. https://content.interlinebrands.com/product/document/10080/2486824_Brochure.pdf

I don't know where you would measure your donut to know if your size matches your hub, but the common donuts I see are called "service weight". I have never used one of these.

 

[StephK]

GOT IT!! Phew, that was a doozie! Ended up grinding the edge of the CI hub, and also the 2” PVC. Then a ton of lubricant, and some manpower from my husband, got that thing in. That was a project that took way longer than expected. But here is the finished product, isn’t she pretty.