Hutch,
Good point!.
In some cases with Plumbers using nasty old busted pipe threading gear that thier Grand- fathers used and abused, it's a wonder that the pipes didn't leak like a sieve here.
I learned how to thread pipes with a machine called a Thred-All and the pipe was held in a Pipe Vice.
Yes even to this day we still use the TPI nomenclature here.
Even, I must agree that there hasn't been a Brass fitting used here that doesn't use the Imperial sizing of either 3/8" or even 1/2" (outer diameter).
I went to buy some Brass recently for a guy I was building a 430MHz Ham Aerial for.
I needed some 8mm square stock for a T-Match and when I told the guy what size I wanted, he looked at me as though I'd sworn in Church.
He then informed me that I would be needing 5/16" stock, with rounded edges, no less!.
Good Grief!. [Linked Image]
I felt like saying to him,"Could you please put the corners back on, it has to be square".
But let's not make life harder, eh?!.