On Sat, 14 Mar 2015 09:34:08 -0500, dpb wrote:

On 03/14/2015 9:00 AM, trader_4 wrote:
On Friday, March 13, 2015 at 4:26:03 PM UTC-4, wrote:
On Fri, 13 Mar 2015 10:02:43 -0500, wrote:

...[ ? galvanized prohibition for NG]...

I've done some looking at various times in the past and have never found
any definitive reasons, either.

The problem w/ the flaking hypothesis (which have heard before too but
never found really documented in a utility handbook/standard) in my mind
is the galvanizing is on the outside of the pipe, they inside is just
black pipe...

I've seen some talk of some reaction w/ trace impurities and the zinc
and all kinds of other speculation but never any clear cut explanation.
The natural gas today is lower sulphur than in the past, the
galvanizing is different, and it has been proven that the actual
incidence of zinc flaking is very low. Also, code now requires a
"condensate drip trap" before all gas appliances, where the flakes and
any other "fall-out" accumulates.

The trap has been there on gas lines for a very long time, it's
nothing new. Like DPB, I've never seen anything that established
the alleged zinc flaking to begin with.

That's my "best read" of the situation. All of my gas is black pipe
except for one little LB that is galvanized because that's all I had,
and all I DIDN"T have in black pipe when I replaced the water heater.
Been 57 months now, and the water heater hasn't gone out yet - - -.

There is plenty of galvanized around here too, including by the gas
company at the meter.

Some NG supplies may be somewhat lower in impurities but most are simply
related to where the gas came from...lower at one place is probably
simply owing to a different source as supplies have changed...as the
Hugoton field around here has depleted over the past 80 years some wells
have started to produce some H2S which is toxic in concentrations of
roughly 300 ppm or so but standards generally require "sweet gas"
concentrations of 25 ppm or less; most take it down farther than that to
the 5-10 ppm levels. Doing that also cleans up other impurities. I
don't know that residential supply standards have changed significantly
in 50 yr or more so really don't think that's a real factor.

Agree on the drip taps; they've been installed here from the time first
got the first feed off the pipeline that Grandpa got in part for the
right-of-way across the land back in the mid-30s. I swapped out a water
heater a couple of years ago that had been in place since, afaik, folks
remodeled the house in the early 80s and there was neither any moisture
nor any discernible solids in the bottom of it after all that time, but
it was there just in case.

The lines are mostly black iron; I do not know what the half-mile or so
of line from the pipeline connection in the pasture to the farmstead
actually is; I don't remember altho I _think_ I recall that Dad ran a
new line back in early 60s when we put in the feedlot and a grain dryer
but I don't remember what it was...I keep waiting for it to develop a
leak and have to replace it...
Generally the old underground stuff was bitumen coated black iron,
with welded and wrapped joints. Stuff lasted virtually forever because
there was no oxygen contact to the iron.