I don't know what a plumber's wrench is; we have pipe wrenches and they
will grip a round smooth pipe.

I would start by applying penetrating oil. Let it soak in for hours,
reapplying a few times. Try inducing vibration to help the oil sink in
(tap the bib with a hammer). If that doesn't work, get a torch and heat
the pipe, not the bib, then let it cool. The idea is that the pipe will
expand with heat, then contract as it cools, which could loosen the
joint. If that doesn't work, heat the bib, but not the pipe. The idea
is that the heated bib will expand, the pipe won't, and that could
loosen the joint. Vibration may also help as you are heating. If that
doesn't work remove the bib and pipe (if the pipe has already turned, it
should be removable easily) and replace. This last might be the best
option, as if the pipe has already turned, you have a potential leak
which could do serious damage before it becomes apparent.

wrote:
I am trying to change a hose bib on outside of the house. The bib is
stuck and I cannot seem to free it up. When I turn it the pipe it is
connected to turns as well. I tried to hold the main pipe with a
plumber's wrench and pliers, but I cannot grip the pipe very well
because it is smooth and round. Should i use lock-tite or is there some
other chemical I can use to loosen the bib's connection from the pipe?