I have galvanized pipe in my 1936 built house, all original pipe except a few updated sections.
My problem now is a piece of drain pipe that runs from my bath tub drain.That section has a spot at a 45 fitting that is leaking badly.
I know the proper fix would be to bust a fitting loose and replace with a new section of galvanized pipe. My fear is that I would stress the old pipe too much and end up chasing busted and leaking pipe all the way to the main cast iron drain pipe.
I would like to cut the 2" galvanized pipe clean and join it with PVC drain pipe up to the tub drain.
What is the best way to accomplish this?

I've seen what you described done with a Fernco.

If you connect PVC to galvy with threads, it is better to have the PVC be the male threaded piece inside the galvy female threaded piece. Male Adapters (MA) often fail where the threads begin furthest threaded end, at least on pressurized lines. The strongest approach seems to be to make your own “MA”, by cutting a schedule 80 threaded nipple in half and gluing a slip/slip coupler on the cut end. This may be overkill for a drain line though.

quote:

Originally posted by M1Garandy:
I've seen what you described done with a Fernco.

That was the answer in my house and several other. Galvy just closes up to nothing inside.

Fernco, I like to change the hose clamps to a better quality one such as an ABA or AWAB brand.

Memories of my dad complaining of the same thing. He hated plumbing in the old house for the same reason. Fernco all the way.

Reading is fundamental. Sigh…

Clearly I wasn’t reading carefully. Our first house had galvy supply lines (all closed up, we ended up replumbing with copper), but the drain lines were all cast iron pipe. If you have galvy on drain lines, you probably want to get rid of all of it asap and replace with ABS. For connecting ABS (the black plastic drain line material) to cast iron the couple you want as many have stated is the rubber coupler with stainless steel clamps, aka Fernco.

Up date:
Last night I took the reciprocating saw to it.
I bought a length of 2" rubber hose with clamps and had some 1 7/8 hose on hand.
As soon as I cut through the 2"galvanized pipe the entire section all the way to the tub pipe broke off,the cast iron catch/trap was too heavy for the corroded galvanized to support. This was my nightmare coming true.
I imagined making the cut, then using a piece of rubber hose to slice the pipe between the cut and the trap, making for a quick fix.
Luckily,having been in this house for over 40years, I have a huge supply of hardware to tap on in emergency's (if I can find it, I know its around)I have a large enough selection of PVC pipe and fittings that I was able to fabricate a new section without a trip to Menards.
I was lucky the the corroded out section was all a low spot that feed into the catch. The place I cut the galvanized was still good because the water sat in the low section not where the pipe was elevated.The tub drain area was also still good.
I joined the PVC pipe to the galvanized with the rubber hose and clamps.
I will take JIMMY123X advise and replace the clamps with the higher quality clamps. I had a FERNCO connector and used the screw clamps that came with it, the clamps that came with the rubber hose I bought, were total garbage.

I was unable to replace the trap but did create a goose neck to stop gas from coming up the tub drain.I like the new set-up without the trap. If I need to clear out that section I can easily drop the whole PVC section by loosening the two rubber connections that hold it to the galvanized pipe and clearing it out.
I doubt that what I created is to Chicago code but will work for now.
Luckily, my house has a basement so the pipe is easily accessible. The failed section "was" covered in drywall, I replaced that with a removable section that can allow access.

Thanks for the advice. I will add a supply of FERNCO connections for all the different pipe sizes for future disasters.

Fernco Is the way to go. They make a few different styles but for a simple home 2” pipe you should be good with a standard one with just rubber and hose clamps on each end. They also make one with two clamps on each end and ones with a metal sleeve that goes over the rubber.

Sounds like your good. If you have any question I’ve done a bunch of repairs to galvanized pipe for home to commercial up to 4”. Feel free to ask here or email me.

Next time don't use a reciprocating saw to cut it, the vibration can be too much, use a hack saw if possible so you can gingerly cut it. Or if you must use a power tool use a 4" grinder with a cutoff wheel, much less vibration.

Don’t want to be a Debbie Downer here, but the lifespan of galvanized pipe is between 40-60 years.

As you’ve discovered, it’s time to re plumb it. You can use PVC for the drain lines-it’s not rated for hot water, so most companies use PEX now because it so easy. Dad replumbed my older brother house a decade ago and it’s all PEX

Chicago has some very old building codes that are still in effect from decades ago. Mostly to protect union jobs.
I don't think PEX can be be used and I'm sure even PVC is very restricted.Electrical has to be run in conduit.

I had a couple plumbers come out a few years back to give me an estimate to replace this section. The bath tub drain,catch, and about 4' of pipe. Everything is easily available from the basement. I assumed about 4hours work.

One Plumber never got back to me, the other quoted over $3000.

Shit! At that pricing, and the rules there, I’d replace with more galvanized pipe just how it is and not pull a permit if it’s exposed and pretend it never happened