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Letter 5892
Copper tubing for internal natural
gas
.
Recently, my father visited us in our three year old townhouse.
While walking through the townhouse development, my father noticed
that the natural gas pipe within the house is copper. It is, of
course, affixed to a steel meter reader. Dad noticed that in a
significant number of cases, the coupler that connects the copper
pipe to the meter reader is severely corroded. He believes that
electrolytic corrosion is taking place.
I have contacted the builder. They have told me that the the
coupler is made of brass, which they say is inert. They believe the
cause of the corrosion is related to the location of our meter
reader, not to two incompatible metals coming in contact with each
other.
We are now in the process of building a new house using the same
builder. Is there any reason at all why we should not use copper
tubing for natural gas within the new house? Is there a good reason
for us to internally use steel pipe for the natural gas? If we use
copper tubing, is there a particular type of coupler that would
ensure electrolytic corrosion does not take place? Many, many thanks
for your insights. Mary
Mary Crane
- Arlington, VA, USA
.
I am not a metals professional or chemist and can't comment on the
mechanism of the corrosion, but have personal experience with this
situation. Copper tubing will be attacked over time by the gas. This
will eventually result in a failure which will result in a gas leak.
For this reason copper tubing will no longer meet code in many areas.
This happened at my house and I was forced to replace all copper
tubing with black iron pipe. You should use iron rather than
galvanized steel because the galvanizing tends to flake off the
inside of the pipe, plugging the orifices in your burners. This is a
serious safety issue and you should insist that your builder use iron
pipe rather than copper.
John Barker
- Des Moines, IA, United States
.
Mary, I would have the same safety concerns as your Dad. I am
frankly surprised to hear your building contractor is using brass (an
alloy of copper and zinc) for gas inside private residences. Around
here (central NY) new gas piping construction uses black iron
threaded pipe which is a less expensive material, and easier to get
installed without leaks. I am, like John, not trained to give you
professional advice, just personal experience.
If you want to get some additional technical background, however,
you can go to the GPO Access site, for US Gov't. and view 49CFR192
sections between about .475 to .490 which generally states the
"common sense approach" that general corrosion that reduces piping
wall thickness by >30%, or any significant pitting, requires
replacement of the piping. If corroded less than that degree,
cleaning of the area, and installing a corrosion resistant coating,
or jacketing that inhibits the contact of corroding agents, is
suitable. (The above is my paraphrasing as I understand this.) I
think a bimetallic coupling, if available, might also help, but these
are hard to find, and to be effective, must be metallurgically
bonded, and closely match the two metallic materials to be joined, or
be corrosion resistant, and non-conducting. I hope I have been of
help, and good luck in you new home.
W. Carl Erickson
- Rome, NY
.
Mary, as others have said, you are probably at the wrong site for
professional advice on this issue.
My father was a plumbing contractor who would never even put in a
steam or hot water boiler with copper tubing. He thought it reckless
to use anything but black iron pipe at a critical hot spot like the
boiler itself. If he hadn't passed away 20 years ago, he would be
having a heart attack right now at the thought of people running
natural gas through copper tubing.
As I say, I'm no expert, but I might have trouble sleeping in a
house with copper tubing conveying natural gas. The short length of
flexible brass tubing to the clothes dryer frightens me, but
fortunately there is black iron piping with a handy stopcock before
the tubing.
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Ted Mooney, P.E.
finishing.com
Brick, New Jersey
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.
Anyone interested in codes for application of copper tubing and
swagelocked fittings, for gas service in private residences, can
learn by checking the "Copper Page" of the Copper Development Assoc.,
and their "Fuel Gas" section. VA may have codes that comply with this
info, now, like many western US states. My previous opinion stands
for now, since I do not have gas in my older residence, because it is
not available in my rural area, but my grown children, who live
elsewhere, do. I really cannot be that certain however, I would be
nervous about this type of piping in any new, future residence, after
checking out this info, if I also had confidence my contractor and
building inspector were trustworthy. Corrosion problems of the gas
supply lines often causes only tiny leakages at first. If this is
detected quickly, (the human nose can detect fuel gases at low ppm
levels), and the homeowner has it remedied immediately, everything
should work out fine.
W. Carl Erickson
- Rome, NY
++
Hello!!!
In answer to your question: Should I use copper tubing for natural
gas? I'm surprised that no one has advised you that over a short
period of time, natural gas causes a build up inside the copper
(Copper Sulfate) and will, at the least vibration flake off and cause
all gas valves to fail. No compentent & licensed plumber would
ever install copper for this purpose. Just call your local code
enforcement office, they'll give you the complete low down.
Ray Timmons
- Denton, TX
+++
Brass is NOT inert. It is more resistant to corrosion than copper,
but will corrode. Galvanic corrosion will occur between the
iron/steel pipe and the brass fitting. placing dissimilar metals
together like that is a very bad idea.
George Waugh
- Shawnee Mission, KA, USA
+++++++
We are in the process of renovating our kitchen and our plumber
installed copper tubing for the gas range. is this recommended?
Thank you,
Lucia Walker
interior designer - Miami, FL
+++++++
Hi, I'm interested to see all the concerns about using copper for
gas. Here in the UK, copper is pretty much all we use. The only
problems I have heard about are from joining copper to steel, where
steel will corrode very quickly. If its all in copper, it should be
fine.
I hope this helps. Terry.
Terry Hughes
- Upminster, Essex, England
January 29, 2008
I'm not a pro, but I thought others might be interested in this
link:
www.copper.org/applications/fuelgas/pdf/Official_Copper.pdf
Contrary to other posts, this document seems to indicate that copper
is okay (in most cases) for natural gas. Cheers.
Steve Bachman
- Ann Arbor, MI
August 9, 2008
Propane uses copper tubing - when copper was approved up here it
was first lead lined - but that dropped a couple years later- Copper
has been used here for over twenty years - but 8 to 10 or more
problems come up with the flaking and restricting the gas thru the
gas valves - what we use is black iron pipe or CSST ( a stainless
steel flex pipe) in new piping systems - we will use copper piping
only if it is accessable like for gas fireplaces for the last couple
of feet, you can have a problem with any piping make - it will depend
on the installer and after the installation servicers. The reason we
don't use copper is you can see areas like the meter and at the
appl.where you can get to see problems and repair them, but not where
it is in the walls - If you have copper piping in your home - the
next time for have a furnace or boiler checked at the end of the
service ask the tec to remove the copper pipe before the gas valve
and see if any flaking falls out and check the screen at the gas
valve and if it plugged and flakes do fall out get another company
next year
Scott Turner
- Surrey, B.C. Canada
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