hj said:
MY opinion is that there is nothing wrong with the pipe. It appears to be the residue from a tiny leak in the lead joint. I would just seal the lead more tightly with a hammer and blunt chisel, or caulking iron if you happen to have one. Then wire brush the rust off. You have a similar appearance at the elbow down at the Y connection. If I were doing it, I would try to find a different point to connect that drain into the system, maybe into the ABS pipe visible in the background, to avoid that sharp 135 degree turn at the bottom.
Although it isn't visible in the photo, the side of the upper elbow is scaling away from rust and theres a 2mm hole all the way through.
This is all moot, anyway, as I cut out the offending section yesterday--from the top of the 45-degree elbow, to the T at the bottom. I made the upper cut flush with the top of the elbow, which leaves me with about 2.5" of pipe to connect a clamp fitting to; at the bottom end, I left about 4" above the T.
The interesting thing is that I made both cuts using my recip saw and a single blade (BLU-MOL 6" 14tpi from Home Depot). To avoid vibration, I used the fastest speed possible while applying light downward pressure. It took me about 10 minutes to make both cuts and another couple of minutes to dress up the pipe edges with a grinder.
So now it's on to replacing with ABS. I'm going back to Home Depot tomorrow, which has a huge selection fo PVC/ABS, but, of course, nobody around who knows a thing about it.
(1) What's the name of the elbow I'm going to need? It needs to connect the 2.5" stub of cast iron at the top to a run of straight ABS pipe .
(2) What's the name of the flexible union that joins the ABS run to the cast-iron stub below? Or do I just buy a length of the flexible material, cut it to length, then clamp it on? If so, what is the flexible material?
(3) Is ABS joined in the same manner as PVC; that is, a primer and a solvent-glue? If so, can I use the PVC chemicals I have on hand?
Thanks again for everyone's help on this project.