I am trying to replace the entire p-trap assembly under my bathroom
sink. My problem is that the old drain extension tube (the part that
connects the trap to the stub-out) seems to be stuck in the stub-out.
The stub-out is cast iron and the old tube is some kind of thin metal
(yes, I am a plumbing novice.) What is the best way to remove the
tube from the stub-out without breaking the tube? Twist? Pull? Do I
need a torch or chemical to loosen it?
In days of old, a "solder bushing" was used to connect
the thin brass tubular trap arm to the "stub out".
The bushing is threaded on the outside and smooth on the inside.
The trap arm is first cleaned of the chrome plating and then
its brass surface is soldered to the bushing ID. Then the
whole mess is screwed into the stub out (which in this case
is probably galv or brass).
Anyway.........if that's what you have, the fix is to saw off the
trap arm as close to the wall as possible. Then use a hacksaw
blade (or a small recip) to saw lengthwise thru the bushing.
That will weaken the bushing to the point where it can be
unscrewed. Usually they are in so tightly that you can't just
unscrew it and there is nothing to grab on either.
To make a replacement, get a "DeSanco" fitting of the correct
size. It will screw into the stub out and has a ferrule
adapter for the new trap arm.
Doesn't sound like you have copper DWV piping, but in those
cases it was common for the trap arm to be soldered directly
into a brass fitting (no threads).
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