Gas copper fittings?

Looking at a basement rental NG furnace, I noticed that the black steel gas pipe was joined to the gas valve with a 6" length of 1/2 copper pipe. Is this legal? Safe? Should not only the black steel, approved for gas pipe be used?
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This is Turtle.
You need to go back to alt.hvac and see a complete run down on this question that you posted earlier.
TURTLE
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NG will eat away at copper. Replace it ASAP.
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years old. As part of a refit am replacing gas line anyway. Also take precaution of always turning off at the propane bottle/tank, a 15 pounder in a separate ventilated locker at stern of boat, when cooker not in use. However there will always be gas in the pipe. Just curious. Terry. PS. Is it because of certain impurities (maybe sulphur etc.) in NG that corrodes copper?
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This is Turtle.
Propane does not react to copper like natural gas does.
TURTLE
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TURTLE wrote:

It's not the "gas" in natural gas that's the problem--it's the sulfur as Terry suspects (normally in the form of the sulfide (H2S) combined w/ the entrained moisture that's the culprit...
LP's do tend to be "purer" owing to the liquification process that produces them from NG...
Here's a study from So Cal Ed on corrosion effect of NG on Cu tubing...
http://www.copper.org/applications/fuelgas/SoCal%20Gas%20Final%20Report.pdf
I don't know as I agree fully w/ their assessment that the localized pitting is innocuous as a failure mechanism but I'm not a real metallurgical type (but I don't get the feeling the folks who did this study were, either). I do recall a particular product I worked on where corrosion attack on SS was dramatic although localized. I can envision similar phenomenon w/ Cu but that's just a "gut feeling", not engineering data.
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Excellent link! Thanks
Rich
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My utility approves K copper for natural gas. It is, as I understand it, the odor agent that reacts rather then the gas itself. So, it depends on what the particular utility uses.
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