Tips on Unscrewing Kitchen Sink Waste Pipe?
 

Josh wrote:
....
everything has gone reasonably well until I tried to unscrew the metal
waste pipe that runs from the trap to the main sewer pipe in the
wall. I'm sure it's been in there since the house was built in 1959
and I can't get it to budge, even with a 24" pipe wrench.

This particular one looks like very tarnished copper, about 7" long
and 1 1/2" in diameter. It appears to be sweat soldered on to a 2"
bushing or threaded male adapter, which is threaded into the main pipe
in the wall. They used a lot of pipe joint compound on the threads,
and it's hardened. I've squirted Liquid wrench on in 3 times, but
since it's running horizontially I don't think it's penetrating very
far.

Any of you professional or experienced amateur plumbers got any tips
on how to deal with it?

I've been using the pipe wrench near the trap, so I won't accidentally
damage the new hot & cold water plumbing. Also, I've got more room to
work out there. Would I be able to apply more torque closer to the
wall (connection)? Not as much room to work close to the wall,
because of the other plumbing.

Most unusual if it's actual the pipe that's threaded; I'm guessing it's
standard compression waste fitting and you need to work on the fitting
not the pipe.

But, can't see if from here...

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Tips on Unscrewing Kitchen Sink Waste Pipe?
 

Why not just leave it, cut off the pipe, leaving enough to put a no-
hub coupling like one of these:


Thanks guys.....That's exactly what the guy who installed my new
countertop (minus sink) recommended I do this morning.
I found one like you referenced at Lowe's. It says it's for 1 1/2
inch pipes of similar or dissimilar material but it seems a lot bigger
than that. Hopefully it will tighten up snug around the cut off
copper waste pipe and the new PVC from the trap.