I'm doing some demo on my 50's kitchen, which was done pretty well,
overall -- 3/4 black pipe to a 6 burner stove, etc.
Except, they tee'd off underneath for the gas line to the oven, using 1/2 or
5/8" copper, flare fitting.
I've been told copper gets brittle with natural gas, and is therefore
against many codes. Is this accurate? Is this a recent discovery? Seems
odd that the original installers would use 3/4" black pipe, and then wimp
out at the end.
Are there similar restrictions with copper and propane? Other gases?
If this restriction is only with nat gas, I assume it's because of the
sulfer additive (smell) that reacts with the copper.
Yeah - I've said it before, but I was surprised when I uncovered* my
propane line and it was 6" down at best and just soft copper - I'd
expected something better, or even double-walled, and buried a lot deeper.
* intentionally, having called the propane company and had the site marked
out, before anyone wonders ;-)
Call your natural gas supplier. I got a lot of good info when I added
a concrete porch onto the back of my house. The project interfered
with the planned installation of a gas line to a fireplace that was
surround on three sides by the patio. BTW the last few feet of my
fireplace installation is with soft Cu tubing, so is my gas water
heater and furnace . The installation was done by the gas Co so I am
assuming it is OK for short terminating lengths. The opinion of your
gas Co may be different.
A study by SoCal gas but no firm conclusions
and a safety brochure by another gas utlitiy
it appears that corrosion in copper caused by nat gas use may or may
not be a serious problem BUT the consensus appears to be that flared
connections are WAY more susceptible to corrosion & failure than
I would not use not recommend the use of copper flared fittings, I
might even go as far as removing existing flared connections.
I would definitively replace uncoated brass or copper flex lines that
service appliances with coated flex lines or SS flex lines.
I would only use back pipe or CSST tube for new work or remodel work.
Gas lines, like water lines, only need to be sized large enough to
supply the appliances served or future possible demand. A 3/4" black
pipe, depending on the run length, can deliver xx btu/hr. The short
supply line serving only the oven may be just fine for the oven
demand, with the 3/4" line acting as the "main". I have a 3/4" line
running from the meter to the kitchen...about 50'. The furnace and the
water heater are served by the same 1/2" pipe (less than 6') off the
3/4" line. The stove and a 5 ton gas A/C were served off the
continuation of the 3/4". The A/C was retired a while ago.
btw the smelly additive (mercaptan?) is added in minute amounts to
give the nature gas a consistent & recognizable smell and is supposed
to be safe, probably way safer than un-smelly gas. Sulfur does
exist naturally in natural gas mainly as H2S but the gas utilities
remove it and add the other smelly stuff. Natural gas with high
amounts of H2S in being referred to as "sour gas", those high amounts
are only 4ppm & higher. Total sulfur content is controlled as part of
their QC process.
If I remember correctly you can't use galvanized pipe for
natural gas but I've never heard of any problems with copper
pipe and natural gas or propane here in the Southeast. The
only thing I know that you can't use copper pipe with is
ammonia refrigeration systems.
In many places in the US, galvanized pipe is now OK. Just like the
discussion with copper there was concern that with some types of nat
gas galvanized could flake off and then clog orifices. But it does
vary from area to area.
but I've never heard of any problems with copper
When I moved a park model mobile home from Wisconsin where it had been run
on propane to Mesa, AZ where it was to be hooked up to natural gas, the city
refused to allow the hook up due to copper tubing being used for the gas
lines. My contractor said he thought the city was wrong and he pointed out
to them that their codes allowed copper tubing if the tubing had a certain
manufacturing code letter (which I don't remember). I had to call the
manufacturer back East to find out where on the copper I could find that
code and then point it and the code regulations out to the inspector from
the city and then it was approved. As I remember it, the copper had to be a
certain alloy to prevent pinhole leaks from forming from the natural gas.
That's sort of what I remember -- esp. the pinhole leaks, now that you
Most of the replies here don't seem to be aware of this, mebbe because only
a few places make this distinction.
Your contractor seems like he was on the ball!
What kind of tubing did you wind up using? Special tubing? Flexible or
That's the whole point--it doesn't make any difference excepting for
what your Code or supplier requirements are.
There are quite a number of studies on the effects of natural gas
impurities on copper alloys as well as galvanized available on the web
but again, they're of no consequence fundamentally to the question of
what your local jurisdiction requirements are.
So, check w/ them and find out...
Well, I was more interested in the actual physical effects, and was
wondering if there was a consensus on this porosity issue.
Codes are not always logical.
NYC had the most oppressive electrical code in the country perhaps, and then
one day decided to lighten up and go with the NEC. Go figger....
Just stuck with the existing flexible copper tubing because it had the
proper letter code to meet code, in the end.
It hadn't made sense to me that the manufacturer would have installed
flexible copper tubing that couldn't be used with natural gas and propane as
they wouldn't have know what the gas source in the field would have been.
On Wed, 04 Nov 2009 17:18:48 -0500, firstname.lastname@example.org wrote:
Sulphur is NOT added to Natural gas. Sulphur in natural gas is
naturally occurring, and is largely removed by processing before
Ethyl Mercapitan is added in VERY small amounts as an identifier
I've seen mostly copper inside buildings and have never had a problem
(about 800 locations).
But IIRC copper is anodic to steel, so if the two are connected the
steel pipe should sacrifice itself to protect the copper. If they
were outside or underground I would guess there could be a problem.
Magnesium, Al, Zn strips would help protect the steel and copper. Magnesium
stakes are sold for this purpose, and anodic aluminum is found in water
heaters -- altho alum is proly not very effective after its own oxidized
Copper outside form a protective oxide, like alum -- that green patina. So
copper should be stable outside as well.
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