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Copper Tubing for Internal Natural Gas?

Q. 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 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, Virginia

A. 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, Iowa

A. 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, New York

A. Mary, 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.

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.

Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

A. 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, New York

A. 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 sulphate) and will, at the least vibration flake off and cause all gas valves to fail. No competent & 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, Texas

A. 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, Kansas

Q. 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, Florida

A. 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

A. I'm not a pro, but I thought others might be interested in this link:
Contrary to other posts, this document seems to indicate that copper is okay (in most cases) for natural gas. Cheers.

Steve Bachman
- Ann Arbor, Michigan
January 29, 2008

Ed. note: Very interesting article, Steve. Thanks.

A. 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 accessible 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 tech 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
August 9, 2008

A. I have been looking into this as well as the Home Depot drone told me copper tubing is fine for gas and I don't trust him. I have just replaced the pilot to my furnace and needed 1/4 inch flexible tubing. My old tubing was aluminium but the guy said they didn't carry that and it makes no difference. So far my research has shown that the problem with gas corroding copper line when used for gas supply is caused by the chemical additive used to add the rotten egg smell. for the past decade or so this chemical has been reduced and or changed and it has been suggested that it will not cause the same corrosion to copper tubing. However, I would assume that it is a question for the local gas supplier on if they still use the chemical and how much. In other areas of the world where the smell is not added there will not be a corrosion to the copper and may be why this question has opposing answers. To be safe I will reluctantly be replacing my tubing with new aluminium stock as soon as I can find some. hope this helps clear things up. Happy Home-ownership :)

Daniel Nonya
- Philadelphia, Pennsylvania
November 17, 2009

A. NFPA-54-09 says:* Copper and Brass. Copper and brass pipe shall not be used if the gas contains more than an average of 0.3 grains of
hydrogen sulfide per 100 scf of gas (0.7 mg/100 L).

A. An average of 0.3 grains of hydrogen sulfide per 100 scf of gas (0.7 mg/100 L) is equivalent to a trace as determined by ASTM D2385 [inactive], Method of Test for Hydrogen Sulfide and Mercaptan Sulfur in Natural Gas (Cadmium sulphate -- Iodometric Titration Method), or ASTM D2420, Method of Test for Hydrogen Sulfide in Liquefied Petroleum (LP) Gases (lead acetate Method).

A. See A.
Copper and brass tubing and fittings (except tin-lined copper tubing) should not be used if the gas contains more than an average of 0.3 grains of hydrogen sulfide per 100 scf of gas (0.7 mg/100 L).

Chris Cooney
- Kettering, Ohio, USA
April 13, 2010

A. I'm a heating engineer here in the uk and copper pipe is approved and widely used for conveying natural gas, propane and butane. Providing the installation is installed and sized correctly you should not have any problems.
However Natural gas contains some small traces of sulfur. This sulfur interacts with the copper to produce copper sulfide, which is a black, crystalline substance that forms along the interior of the copper pipes. This copper sulfide can be a huge detriment to any system, since it creates a pipe blockage that is never good when you have a system under pressure.
As the interaction of the copper pipe and the sulfur is forming the copper sulfide, the copper comes out of the piping. This weakens the pipe, as the copper is being drawn out of the pipe and into the copper sulfide crystals.
As the pipe fills up with copper sulfide the pressure grows steadily higher. This isn't good, especially because a natural gas pipe system is already under pressure. With the weakening of the copper pipe and the creation of a larger and larger block it can lead to a rupture of the pipe

Dave Eastham
- Kendal, Cumbria, UK
December 2, 2014

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