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topic 13277

How long does it take for natural gas to corrode copper pipes?

A discussion started in 2002 but continuing through 2018


Q. I recently bought a home and almost immediately had a terrible gas leak. It turned out that the gas pipes for part of the heating system is copper and had corroded. I understand that copper pipes for carrying natural gas is not up to code in California. However it appears that copper pipes for gas were allowed at some point in time. Can anyone tell me how long ago Copper was considered OK for gas pipes. Also how long does it take for gas to corrode copper?

Seema Nanda
- Los Angeles, California

International Fuel Gas Code
from Abe Books



A. Natural gas does not [itself actually] corrode anything, including copper. Corrosion is a chemical reaction between metal and oxygen. It is the oxygen in the normal air that is mixed in with the gas that would cause any corrosion. The corrosion may also be accelerated by heat and moisture. Is it possible that humidity or water got into the pipe? I don't have the info on gas pipe specifications, sorry! I do highly recommend that you use whatever material is current California code. Natural gas leaks are not something you want to mess around with.

tim neveau
Tim Neveau
Rochester Hills, Michigan


A. I was a gas service representative for a few years and was instructed that natural gas in copper pipe over some period of years caused copper sulfites which clogged up the pipe with hard, black crystallization. Reps regularly recommended customers switch to galvanized pipes when feasible and steel flex hose connections to gas shut off valves.

Mary Lou Bonilla
- Fresno, California


A. I am employed in the plumbing industry, and most Natural Gas piping is installed by plumbing contractors. It is my understanding that gas has no effect on the copper pipe itself; the problem is the way the pipe is joined. When the pipe is joined with plain old solder that is used for water piping, it will flake off and build up causing problems. When installed correctly, using silver solder, flared joint and mechanical press joining, copper can be the most economic way to install gas pipe.

William J. Stanton
- Waukesha, Wisconsin

Uniform Plumbing Code
from Abe Books



thumbs up sign My father was a licensed plumber then a plumbing contractor for his whole life. He is probably rolling over in his grave at the fact that his son would even let someone post a recommendation here that copper be used for natural gas :-)

I have no qualifications in the subject myself, just my recollection of him fuming the several times he saw it :-)

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


A. LOL, hello guys I'm a licensed pipefitter/plumber/gas technician , personally I've never seen a copper pipe being corroded by the gas itself. Corrosion is usually the cause of what's in the oxygen we breathe, and/or the mixture of different metallic fittings -- and to use copper tubing with just regular solder is totally forbidden here in Canada, only silver solder is permitted. And a service man must be pretty lazy to use copper tubing unless it was in an extremely confined space where steel pipe can't be fitted.

Trex [last name deleted for privacy by Editor]
- Sherbrooke, Quebec, Canada


Q. I have a remote camp in Maine, which is off-grid, and where I use LP for lighting, refrigeration, and kitchen range, and may expand to other uses as well. With the recent rise in the price of copper, our region has experienced increased theft of copper, and many camps have been raided for their copper tubing. My question is: What alternatives to copper tubing are there that are homeowner (do it yourself) friendly, that will remove the temptation of thieves from ripping out my gas lines?

Brian Athorp
- Dedham, Maine


The only thing I see in my area is natural gas rather than LP, but black iron pipe is all I ever see in my home and the homes of family and friends, Brian. I suspect it's okay for LP, but I'm confident that there are codes you should check. Good luck.

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


Q. The gas line to my water heater is a copper tubing. A plumber told me that the additive put in natural gas corrodes the copper from the inside out. Since I don't know about copper, I had no reason not to believe him. I am wanting to know if this is true or not.

Gloria P

Gloria Plank
consumer - Pearland, Texas

February 11, 2008


- CONCORD, California

March 21, 2008

A. As an applications engineer in the metals industry, I know a little bit about corrosion. Enough to be dangerous, anyway.

Natural gas on its own may not have a huge corrosive impact on copper. And copper is typically not corroded by oxygen due to its noble nature. What will corrode copper rapidly is oxidizing or reducing sulfur environments. Sulfur is added to natural gas to give off the rotten egg smell to warn us of leaks (without it, natural gas is actually odorless). This sulfur is probably what attacked your copper line.

The above is only my guess.

Alex Mak
- Vancouver, BC, Canada

December 29, 2008

A. Copper is ok, flare fittings are best.
Test with liquid soap or gauge.
Black steel is best indoors but no one wants to work anymore so they have this new stuff called track pipe.

Anthony Schiavone
- rye brook New York

January 30, 2009

A. Been installing water heaters for many years now. TRUST ME, BLACK IRON PIPE or GALVANIZED ONLY for ANY gas line! That's it that's all! I could write pages and pages of why you shouldn't use anything but those two materials, but won't. If you want safety first, follow my years of experienced advice!

Kevin West
- Sunnyvale, California

June 27, 2009

A. Copper pipe, or tubing is NEVER ALLOWED BY CODE IN THE US FOR NATURAL GAS DISTRIBUTION! There are various reasons for this which I'm not going to even bother getting into because they are irrelevant. Bottom line is copper is NEVER ALLOWED BY CODE IN THE US FOR NATURAL GAS DISTRIBUTION!
It is very common to see copper tubing used in rural areas for propane gas distribution. This is allowed. Propane and natural gas are two different gasses.
Steel pipe is allowed in residential and commercial construction inside of buildings. There is direct burial plastic tubing types allowed outdoors, underground. They must come out of the ground via a steel riser.
If you don't want to use rigid black steel or rigid galvanized steel, and go through the trouble of cutting and threading, there are different brands of flexible, stainless steel, plastic sheathed tubing (Ward-Flex is an example) that can be used, but this requires a license or permit to purchase in most areas.
Also, CAST IRON fittings may NOT be used either for propane or natural gas. They are for steam fitting and DWV (drain, waste or vent) installations. Malleable iron only!

If you have copper in your building used for natural gas, I strongly suggest replacing it ASAP!

Also, if you live in an area where propane was used, and the public utility has extended their service area to include your home, before converting to NG, I would advise checking your system first to make sure a previous contractor has not plumbed your gas with copper. It will need to be changed.

Scott McManus
- Binghamton, New York

November 17, 2009

A. This quote answers the question:
"Copper and copper alloy tube (except tin-lined copper tube) should not be used if the gas contains more than an average of 0.3 grains of hydrogen sulfide per 100 standard cubic feet (scf) of gas (0.7 mg/100 L)." (

For the most part the chemical added to make the gas smell is what corrodes the copper and not the natural gas itself. If your local gas supplier has reduced the additive to this amount or substituted sulfides for something else you would be ok. But for safety I'd suggest using black pipe for supply and coated flexline or flexible aluminium line for compression fittings.

Daniel Nonya
- Philadelphia, Pennsylvania

December 17, 2009

A. I do not know the US Code, but the Code for natural gas in Canada is as follows...

"Natural Gas can be run with

-Copper tubing DESIGNATED and rated for natural gas by use of flare fittings only

-Black iron pipe schedule 40 or thicker with only black malleable fittings (NO GALVANIZED PIPE OR FITTINGS ALLOWED)

-Polyethylene pipe for underground installations only

-Corrugated Stainless Steel Tubing CSST

-Steel tubing DESIGNATED and rated for natural gas by use of flare fittings only"

Remember, the copper tube allowed in Canada must be the type rated for Natural Gas, regular retail stores do not carry this type of tubing, only HVAC suppliers have it.

Ronvall Lentin
- Hamilton, Ontario, Canada

January 24, 2010

! I'm a plumber (for twenty years). We install gas lines, but I don't know it all. Worse than not knowing it all, there is a lot of myth and hearsay among plumbers--especially Canadian plumbers--just kidding, co-worker is a chatty Northerner. Anyway, I've always heard that copper is not allowed for gas distribution but I couldn't really remember why except for a faint recollection of it having something to do with an additive. It's in the plumbing code. You can get away with it in some places but why try.

Unless you're like me and on a Sunday you decide to adjust the location of your pilot on your wall furnace because the "the plumber" before you put it too far from the fire box hanging loosely in the air only supported by the ALUMINUM gas supply tube (ha! got you guys! no one has mentioned aluminum yet have they!) to which the furnace pilot is attached. So I grabbed it, move it, and it snapped (I'm more of a big pipe, new construction type of plumber guy). So I'll use copper for a few days until I find a place that sells 1/4" aluminum tube that's open when I get off from work. I wasn't sure how long I could get away with it.

Thanks for the info everyone!

Robert Bustamante
- Los Angeles, California

March 14, 2010

Q. I am a Property Inspector and I remember reading about dissimilar metal connections in plumbing. I can't seem to find materials on the impact this has on gas pipes but if the copper pipes are in contact with sheet metal that is used in ducting, particularly if it is galvanized sheet metal, does anyone feel that this would cause a galvanic reaction which would cause it to corrode over time and eventually leak.

I am very concerned about this and would like some opinions from gas fitters.

Mark Johnstone
- Vancouver BC Canada

March 18, 2010

Q. Does propane damage copper pipe like natural gas? A boat surveyor said that propane damages copper pipe over time, however I don't see any sign of deterioration.


Dave Shively
boater - Aurora, Oregon

Ed. note: Scott M claims in his entry of 6/27/09, that copper is widely used for propane, and your boat is another example. Letter 5892 claims the same.

October 18, 2010

Q. I have an older boiler that the pilot would not stay lit this year. Upon closer inspection I found the aluminum tubing had corroded in just one spot. It was touching the metal frame on the floor. I found it when I lit the pilot and two other flames started nearby. After removing it most of the aluminum is in good condition except where it touched the frame. Is this normal or what?

Dan Mates
- Kalamazoo, Michigan

October 25, 2010

A. For a less anecdotal and more engineering oriented response to the question go to COPPER.ORG and search 'natural gas'.

Ernie Ruda
- Atlanta Georgia

Basic Plumbing
from Abe Books


October 25, 2010

thumbs up signHi, Ernie. Can you please point us to a specific article or articles on that trade-group's site? I followed your instruction and was presented with a list of 754 articles, the first few of which seemed to me to offer no sense of balance at all (which is probably to be expected from a trade group whose mission is to promote the use of copper). I agree that engineering oriented responses trump anecdotes, but to my mind neutral & impartial anecdotes trump one-sided sales literature :-)


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

November 4, 2010

A. The following excerpt is from, search 'natural gas", Fuel Gas Distribution Design Guide:

Based on tests carried out by the Gas Research Institute, and with more than 35 years of successful use of copper by certain gas companies in the United States, major code bodies in the USA and Canada have approved copper tube for fuel gas systems. In 1989 in the USA, provisions for the use of copper tube and copper alloy fittings for interior distribution systems were incorporated in the National Fuel Gas Code (ANSI Z223.1/NFPA 54). Similar provision is made in the Canadian document CAN/CGA-B149.1, Natural Gas Installation Code. Since then, there has been an increasing demand for information on this application. The National Fuel Gas Code also provides for the use of copper tube and copper alloy fittings for underground service lines from the main to the meter."

Kevin Kiefer
- Marietta, Georgia, USA

July 21, 2011

! I am shocked at all of you. To trust the safety of your lives and those surrounding you to the internet! I have seen way too many "He said he knew how to do it"! In reading the answers above if I were a laymen I would be more confused. Call a PROFESSIONAL ... Codes change, what was deemed ok in the 60's is so far out of date.. example (flex lines were made from brass, aluminum etc., but are no longer used). Codes change due to research and well DIY Boo Boo's and etc..
Please call a professional in your area for advise and codes in your country or state or county or OMG city.

Tom Smith
appliance service - Kingman, Arizona

July 21, 2011

Hi, Tom.

I certainly can't argue with your advice in the abstract; the internet should be used only to help find authoritative documents and to open minds to things that should be considered. Trusting internet information is dangerous; someone could even claim to be a licensed professional, while actually being a hacker using a fictitious name and up to no good. When sections of codes are quoted here, I would hope that people use those citations to find those sections, not as a substitute for looking at the code themselves.

My father was a master plumber and I remember the endless evening hours he spent practicing lead wiping and other skills for the hands-on examinations. It's easier these days, but even today to become a master plumber in our area still requires 8000 hours of OJT and 700 hours of classroom time. Yes, master plumbers are professionals -- you don't have to sell me on that!

But the reality of the situation is that I recently bought a gas clothes dryer and a gas kitchen stove with "installation". The "installers" in both instances were big and strong -- an important qualification for such work. But when I questioned them about the adaptors and flex connection gas lines they were putting in (with the same channel locks they used as hammers and for nuts and bolts) they were clueless about what they were doing. They didn't have the vaguest idea whether yellow teflon tape or pipe dope belonged or didn't belong on the gas line work they were doing. They also "installed" water line tubing with a hairline split in it to the icemaker on the fridge, causing a lot of water damage by the time the water leaked out from behind the cabinets. Thus there is value in a homeowner having some feel for what is right and wrong...

We won't become master plumbers from 10 minutes of reading ... it takes 8700 hours. But it just might help spot dangerous work by an unqualified installer -- which seems to be most of them when one buys an appliance with installation service these days :-)

Thanks, and Regards,

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

August 9, 2011

A. Copper pipe, type L or K is allowed under the Uniform Plumbing Code. Section 1209.5.2.3. Copper and brass pipe may be used if the gas contains no more that an average of 0.3 grains of hydrogen sulfide per 100 scf of gas (0.7 mg/100L).

We use it in Seattle because our gas doesn't have that much HS. Your town might. You'd better be sure. Lots of places are now allowing plastic PE pipe. The gas company here now sets all of its new lines in plastic. Professionals can buy plastic PE pipe for light commercial and residential projects. Many rules surround how it can be installed though. Not something I would recommend for a DIY'er.

PJ Lewan
- Seattle, Washington, USA

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