Copper tubing and natural gas?

Posted by on November 4, 2009, 3:26 pm

On Tue, 3 Nov 2009 09:51:02 -0500, "Existential Angst"

>Awl -
>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.
>tia

A quote:

Natural gas in copper pipe over some period of years causes copper
sulfites which clogged up the pipe with hard, black crystallizations.

Posted by on November 4, 2009, 5:18 pm

>A quote:
>Natural gas in copper pipe over some period of years causes copper
>sulfites which clogged up the pipe with hard, black crystallizations.

It also appears that the sulfur added to the natural gas is corrosive
to copper.

Posted by on November 4, 2009, 6:16 pm

On Wed, 04 Nov 2009 17:18:48 -0500, tnom@mucks.net wrote:

>>A quote:
>>Natural gas in copper pipe over some period of years causes copper
>>sulfites which clogged up the pipe with hard, black crystallizations.

>It also appears that the sulfur added to the natural gas is corrosive
>to copper.

Sulphur is NOT added to Natural gas. Sulphur in natural gas is
naturally occurring, and is largely removed by processing before
distribution.
Ethyl Mercapitan is added in VERY small amounts as an identifier
odour.

Posted by TimR on November 4, 2009, 10:03 pm

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.

Posted by Existential Angst on November 4, 2009, 11:22 pm

> 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
film occurs.

Copper outside form a protective oxide, like alum -- that green patina. So
copper should be stable outside as well.
--
EA

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Copper tubing and natural gas? - Page 4