On 1/23/2011 5:39 AM Art Todesco spake thus:

On 1/23/2011 2:24 AM, DD_BobK wrote:

On Jan 21, 9:19 pm, wrote:

Was at Lowes tonight picking up stuff for hooking up my HW heater
this weekend and found out they did not have anymore 1/2" Tee's
in black iron for my gas line. But they had galvanized 1/2"
Tee's. Can I mix the 2?

I asked this question of my mechanical engineering mentor nearly
~35 years ago. He's long gone& I have mixed installations that has
been in service for over 30 years.

He's comment to me back in the 70's was........

"The myth that natural gas causes galvanizing to flake off is an
old wives tale that has debunked by testing, go ahead and use it"

Here is a link to pretty detailed thread on the subject, including
cites from the IRC.

http://www4.iccsafe.org/cgi-bin/ulti...c;f=2;t=002632

a couple guys go back& forth but I'm putting my money on the IRC,
posts in the cited thread by dsjtecserv& my mentor. He had YEARS
of industrial mechanical engineering experience, including being
the chief engineer on design& construction of a natural gas to
fertilizer plant.

YMMV but has been pretty good so far

Well, when I was a kid in the 50s and 60s, someone told me that
black iron pipe is used for gas because, when tightening a joint,
the pipes grind into one another making a tighter seal. I don't
know one way or another .... that's just what I was told. I've
heard all the other "tales".

What you heard was essentially correct. When you tighten a pipe fitting
with any kind of metal pipe--black iron, galvanized, brass, bronze,
etc., both threads deform--in other words, get squished--enough to
remove almost all gaps between them. That's how pipes get sealed. (What
few microscopic gaps may be left are filled by Teflon tape or pipe
thread compound.)


--
Comment on quaint Usenet customs, from Usenet:

To me, the *plonk...* reminds me of the old man at the public hearing
who stands to make his point, then removes his hearing aid as a sign
that he is not going to hear any rebuttals.