On Sep 22, 11:13*pm, Josh wrote:
I'm replacing my old kitchen sink and all the plumbing underneath it.
I'll probably use all plastic/PVC for the drain pipes. *Anyway,
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.

There is always the slip-a-length-of-pipe-over-the-wrench-handle
trick, to increase leverage. I have a 3 ft. and a 5 ft. length of
pipe I keep for that purpose. It has worked many times for me. Of
course, when you are applying a lot of force like that there is always
some risk of damaging something. --H