Removing galvanized steel pipe from cast

[jdkimes]

I have two instances where some threaded galvanized steel pipe runs runs into some hubbed cast iron. I want to replace the steel portion with ABS but wondering:
1. How do I get that steel out? (Is it really threaded in there as it appears?)

2. How do I go from the hubbed cast iron (in one case a 90 deg-T)to the new ABS? I guess I use a "fernco" type adapter?

[jadnashua]

My guess is that it is leaded in...if you scratch the stuff around the pipe, can you tell?

You'd have to clean the oakum and lead out then use one of the doughnuts or plastic lead to set in a new pipe.

[jdkimes]

What are you referring to with "doughnuts" or "plastic lead"?

I guess the other question is: Should I worry about it? The house is 50yrs old and the steel pipes look ok, but tearing a bathroom apart and have access to them so if I'm to do it now is the time (I guess I'm assuming they're likely to rust out)

[jadnashua]

Fernco makes a special rubber shaped like a doughnut that makes a fiction fit when installing plastic into cast iron fittings.

An alternative to doing a leaded connection (which won't work with a plastic pipe) is a special plastic. I've never used it, but read about it here. It may or may not be a viable alternative, but look into it. The doughnuts are often referred to as a pain to get to seat, but I've not done that either!

[jdkimes]

The thing about these steel pipes that where they go into the cast iron they are threaded. Why would they thread them if they were going into a cast iron hub?
So what are all the options to go from an ABS into the cast iron hub?

[casman]

I had galv with threads into cast and I unscrewed the cast and replaced with pvc. I used a threaded pvc fitting with 2 inch pvc and it fit no problem...Did I do this wrong? or am I missing something...

[jadnashua]

If it was threaded, and you replaced it with threaded...all is well.

Trying to remove a threaded connection can be a pain when it is really rusted. If you do get it out, and the threads are still intact, then you can put in a new piece...you might need a lot of pipe dope to make a good seal.

[jdkimes]

Good to know. Are there any trick to loosening the thread/pipe? WD-40, heat, cold...
Also, I worry that I'll mess up those cast iron lead/oakum joints if I put too much pressure on trying to unscrew the steel. How tought are they?

[kordts]

Those fittings are tapped for IPS. I usually bang on the hub with a hammer, bang some more, then put a good sized pipewrench on the pipe, apply torque, and start banging, works almost every time. It never hurts to spray penetrating oil first.