Hi Vic,
You were wholly correct - the nipple was badly rusted - but even so, as you predicted, it certainly would not crush easily.
I snapped this picture of my sister's sink, showing WHY it was impossible to run a snake through the top, without removing the strainer basket apparatus:
My Easter temporary repair was badly leaking, so much that she had placed a bowl but it still allowed the pipes to leak:
There was a twist fitting at the top of each sink, which was easy to remove with a pair of curved locking pliers:
With the two sink compression fittings off, the plumbing just fell out of the nipple (it was NOT twisted into the nipple!).
Applying penetrating oil was probably too little too late, as it did absolutely nothing - even after banging for 10 minutes, which only served to loosen up crud which piled up below:
A closeup shows there was potentially more nipple sticking out than I at first thought - due to a corroded faceplate:
The faceplate would not spin off, but it peeled off easily. Now I could finally see WHAT the nipple was screwed into:
Applying heat sounds like a good idea, but, in reality, it was a bad idea as the wood started burning. I couldn't figure HOW to apply heat to JUST the pipe that the nipple was screwed into!
Now it was time to twist the nipple off. I lined up my curved jaw pliers and my pipe wrenches, and, one by one, they each failed:
This fancy offset pipe wrench was the worst disappointment of all! It wouldn't bite in the least, no matter what I tried. It just kept slipping. I realized at that point that it did NOT have serrated jaws. The jaws are perfectly smooth. Which is useless!
This curved-jaw vise grip also failed its promise. It wouldn't stay on as I twisted, no matter how hard I clamped it down on the nipple:
So, it was back to the basic pipe wrenches! I lined them up, starting from the smallest to the largest - to try to remove the recalcitrant nipple:
The smallest pipe wrench fit and bit beautifully; but lying on my back, pushing UP with the wrench (it would not fit on the left side, pushing down), was a dismal failure. Nothing budged.
The third pipe wrench size fit perfectly - but again - it would only fit on the right side, which necessitated lying on my back and pushing upward to try to spin the 1960s rusted-on nipple off:
I banged. I pushed. I swore. I banged and pushed s'more. I failed:
After an hour or more of getting nowhere, I finally decided to listen to your suggestions and to move on to plan "B", which was to use the Fernco fitting:
Of course, the Fernco fitting necessitated cutting off the female threaded coupling that was supposed to be threaded onto the male nipple:
At this point, I belatedly realized that, even with a trunk chock full of tools, I had forgotten to bring a hacksaw, and, my sister had no tools that would have done me any good. So, I fabricated a quick jig out of an angle grinder & some nearby brick ornamental work - which allowed me to spin the pipe into the stationary angle grinder - and I was able to sand down the rough edges on the concrete (which worked surprisingly well!):
I had only PVC cement with me, so I headed off to the hardware store to pick up ABC cement, which I used to glue the new
45 degree elbow and straight pipe onto the threaded end of the P-trap horizontal pipe:Finally, I wiggled it all together, and, tested it with a sink full of water - and while it looks like hell, it didn't leak anymore (which was the primary constraint). I'm not sure how long this will last (I really preferred to put a new nipple on), but, as Oren is fond of saying, "It looks OK from way out here":
I DO have some questions - but this post is long enough that I will put them in a separate post.