I plan to replace a good portion of galvanized Pipe with PEX. I've
read a few articles on the subject, and it looks fairly straight
forward... unscrew the old pipe, put on a threaded plastic connector
and attach PEX to it.
How likely is it that my 1965 built house's pipes will break under me
trying to unscrew them? If one breaks I'll have to buy a set of dies
and rethread the darned thing, and I really don't want to do that.

My mother-in-law recently asked me to take a look at their leaky kitchen
faucet. I figured it would be a simple gasket or valve replacement.

Turns out the faucet spout was corroded and the part was no longer
available (or at least too difficult to find locally). It was a wall
mount faucet which also turned out to be difficult to find (at a
reasonable price). I thought I had gotten lucky when I found a
replacement in the back of a bin at the local home center, and rushed
back to my in-laws to install it.

Unfortunately, when I went to unscrew the faucet, the pipe in the wall
twisted off instead.

So I bought a special tool to try to remove the pipe from the next
fitting. No go, it just crumbled until the fitting was destroyed also.

Figured I'd try to remove that fitting and replace, but it busted off
inside the wall.

I decided to just replace the vertical pipes running in the wall with new
ones to the basement. So, I started removing pipes and fittings. It
seemed like every fitting I went to remove cracked or crumbled in my
hands. The final 10 foot section of pipe split lengthwise down the entire
length! I thought to myself "You've got to be kidding!" By the time I
was done, there was only 5 feet of the original plumbing left. So, I
decided to just replumb the house since the majority of it was already
out.

Of course, the old faucet mounted to rigid galvanized pipes, and the new
CPVC piping wouldn't support the faucet. And there was no way to install
bracing without tearing into the wall. I certainly didn't want to go
there after everything that had happened so far.

In the end, I decided to replace the kitchen sink with one I could mount
a standard deck mount kitchen faucet to.

So, the moral of this story is hope for something simple, but expect the
worst. In my case, a leaky faucet turned into a complete replumbing job.
My in-laws have a new sink and faucet and much better plumbing now, but
it wasn't the project I had been planning for.

If the pipe joints look rusted like they've been dripping water, or you
see any signs along the pipes of pinhole drips, expect the pipes to
break.

Anthony