jack wrote:

I have a question for the experts regarding the all brass (metal to
metal) compression fittings as used on the water supply lines to the
behind the tile, shower & tub valve sets.

Briefly, is there a right or wrong way to install these things?

In our remodel, the contractor's plumber installed the rough-in valve
sets, then was called back when we discovered a leak from the fittings
on one set. He added more teflon tape to the compression fitting
threads and reinstalled. Still leaking. He cranked down harder and
managed to pull the nipple right through the nut, shearing the brass
shoulder inside the nut. He then declared the valves defective.
These are NOT cheap valves (EXPO Dolphin brand).

There were 2 identical sets installed, tub & shower. Later we found
the other set also leaking. At that point, I had the remaining valve
set removed & the pipes temporarily capped.

I'm now having problems with EXPO on warranty return because the
plumber apparently threw out the bottom parts of the fittings.

I'd appreciate comments. My suspicion is that the plumber has more
muscle than brains or experience, but I'm not an expert. Probably not
likely we can prove one way or the other, if it even comes to that.
Since then, I've inspected similar fittings on known brands; some were
more robust looking but others were essentially identical to the
failed valves.

Is it common practice to use teflon tape on these fittings? Seems to
me that if that's needed to stop a leak, the game's already lost & the
teflon may only be a short term fix since the seal is not supposed to
be at the threads. I have no desire to criticise someone's work, but
I don't want time bombs installed in my walls either.

Thanks for any help,
Jack
if you have a general contractor doing the job, let him deal with the
plumber, that is his job... if the plumber ruins the fittings, the
general contractor has to make good with another plumber to get the job
done.....