An answer concerning copper usage with natural gas

I wrote to an engineer concerning the usage of copper tubing with natural gas. I asked him why it wasn't allowed until the mid 80's and what change took place that permitted its usage.
Listed is the kind reply from Andrew concerning Copper Tubing being used with natural gas.
Your question was: In our newsgroup, Alt.HVAC we are discussing the use of copper tubing being used for Natural gas. We know that it is allowed now, but this was not allowed until the early 80's. Use on propane however was permitted.
Why wasn't copper permitted until then for natural gas but was permitted to be used with propane?
What has changed since then?
Does copper or flake or not when exposed to Natural gas? I was always under the impression that natural gas wasn't as purely refined to remove sulfur to an acceptable level and probably the refining has improved, is this correct?
Thank you very much, and I hope you permit me to copy and paste your reply on the newsgroup or you may visit the discussion and answer it there under 'gas and copper fittings'.
Thank you very much
Rich
Response: Dear Rich,
Sorry for the delay in answering your inquiry.
While copper wasn't included as a recognized material in the National Fuel Gas Code until 1989, it was widely used for natural gas systems in various areas of the country. Areas such as the state of Minnesota, Birmingham, Alabama and surrounding areas, St. Lous, Missouri, and the Washington D.C. area. Most of the areas have successfully used copper for natural gas distribution for 40-plus years.
However, other areas of the country did not permit the use of copper in natural gas systems. The main reason being a difference in the quality of the natural gas being supplied. In those areas where copper was used successfully, their natural gas streams were either naturally low in hydrogen sulfide, or they processed their gas to remove hydrogen sulfide. In areas where the levels of hydrogen sulfide were high, they didn't allow the use of copper, or if they did use copper found that they would experience black flaking caused by the reaction of the hydrogen sulfide with the copper tube. In general, even in the worst systems reaction was not sufficient to cause failure of the piping system, but the flakes could result in nuisance service calls if they blocked burner orifices, valves etc. and resulted in a gas blockage.
As the natural gas industry has evolved, the treatment of gas streams to remove hydrogen sulfide gas has steadily improved, and requirements to control the level of hydrogen sulfide provided in gases either supplied to or taken from interstate pipelines has resulted in a reduction of hydrogen sulfide levels in most gas streams to levels that eliminate the flaking concerns previously encountered in copper systems.
As you had stated, this was never a problem with LP gas systems because the hydrogen sulfide levels in these "manufactured" gases were more tightly controlled.
As a result of the improvements in natural gas processing, the industry is now able to take advantage of the many benefits that copper has been offering for LP gas installations for many years.
I hope this answers your question and again I'm sorry for the delay. If you would like more information please feel free to contact me directly.
Best regards, Andrew G. Kireta Jr. National Program Manager Copper Development Association Inc. P.O. Box 940 Franklin, IN 46131 phone: 317.346.6442 e-mail: snipped-for-privacy@cda.copper.org
Your contact for this case is: Andy Kireta Jr.
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I had a house built when I lived in St. Louis in the early 90's. All the new homes were using copper (brazed) for natural gas lines in the house.
Interesting post.
Thanks

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Brazed? I don't think that is legal under NFS. When I get time I will look into it further unless someone beats me too it
Rich

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    It's at least certainly against code in SOME areas. That word in the post caught my attention, too. In at least some areas, you can not use any heat-dependent method to assemble any kind of fuel piping, based on the idea that repairs will also involve heat, but now on a line with fuel traces / vapors in it.
wrote:

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I just looked up the National Fuel Gas Code (1992, if someone want to post the newest update I would be thankful)
Section a.2.6.2
"Copper and brass pipe shall not be used if the gas contains more than an average of 0.3 grains fo Hydrogen Sulfide per 100 standard cubic feet of gas (0.7 milligrams per 100 liters) Threaded copper, brass, or aluminum alloy pipe in iron pipe sizes shall be permitted to be used with gases not corrosive to such material. "
Section 2.6.3 Copper tubing shall comply with standard Type K or L for SEAMLESS Cooper water tube ASTM B88 or SEAMLESS copper tube for AC or refrigeration field service ASTN b280"
Here is the interesting section that DOES permit brazing, I wanted to point this out before but I needed time to explain why it seems impossible to meet the code.
Read this section carefully.
Section 2.6.8 (a) "Pipe Joints shall be threaded, flanged, or welded, and not ferrous pipe shall be permitted to also be brazed with materials having a melting point in EXCESS of 100F (539 C). Brazing alloys shall not contain more than 0.05 percent phosphorus."
I have looked for years for a brazing material that meets that qualification and cant find one. Has to be over 1000 degrees F and less than .05% phosphorus. I ran into this problem back in 1995 with propane where the job was requiring brazing but Harris and others didn't have anything that had that low of a phosphorus content. So, if the product isn't available then you can't braze it according to code.
Rich Ps, why don't I have a current updated NFGC book? because little has changed even in the last 12 years.

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Yeah, that's what the plumber told me: They have to use brazing for the copper gas lines due to the higher melt temps than solder. (I guess the idea is that it gives you a few more minutes to get out of the house before it blows.)
In addition to brazing, the gas lines had to be Type K, while the water system was all done in L.

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But it you look at this link I cant find one product that is below 5% phosphorus and the code says not to exceed 0.05% phosphorus. So, the code allows it but there isn't any product that I know of that satisfies the code! I would like to know what the plumber used because I have not in 15 years found a product that is legal to braze with according to this code.
Anyone know of any product that meets +1000 degrees F and .05% or less phosphorus?
Rich

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45% silver should do the trick. J W Harris makes several allows with no phosphorus. Yhey come in coils, not stick. You must use high temp flux with them.
Stretch
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Oscar_Lives posted for all of us....

gas be at explosive concentration? Wouldn't it be too high?
Remember, I'm not a tech and don't pretend to be one like some others...
--
Tekkie

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Depends on the gas, and concentration....If its outside of the LEL and UEL then it shouldn't be a problem. I wouldn't want to do it myself, but it could be done

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Heres the link I forgot to post.
http://www.jwharris.com/jwprod/pcubrazealloys/
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Just received a reply from Harris about what product CAN be used to braze copper which is to be used for Natural or LP gas
Here is the reply.
Hi Rich The code calls for a BAg alloy which refers to a brazing alloy which is high in silver and has no phosphorus in it at all. All our high silver brazing alloys ABOVE 15% will work for you because they all melt above 1000F and have they have no phos in it. I usually recommend the Stay-Silv 56 first then the Stay-Silv 45 and last the Stay-Silv 30 (Solidus-Liquidus) The 56 melts at a temp OF 1145F 1205F The 45 melts at a temp of 1250F 1370F The 30 melts at a temp of 1250F 1410F The 45 flows the best of the 3
Mark Koetter Technical Representative J.W. Harris Co. Inc. 4501 Quality Place Mason Ohio, 45040 513-754-2000

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    I don't care what anyone says, Rich, you're OK :-)
wrote:

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I don't like to use copper in resi jobs because it's too soft. It's pretty hard to put a drywall screw through iron pipe. I've seen too many copper pipes penetrated.
But then I don't quote on resi jobs either.
Dave
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Your post makes me remember when a person told us the furnace we put in was spewing propane in the house! They bought a new refrigerator, it was delivered the same day that they started their new furnace for the heating system. And some how the new refrigerator had propane gas in it and they shut off the propane tank and called us (Randy). Well, guess what happened?
The HOMEowner in an effort to save some bucks wanted to hook his ice maker up himself and tapped into the propane gas line thinking it was a water line. Luckily he didn't pierce the line it all the way and it was just a small, I mean small hole so there was a 'hint' of odor. I can't believe the luck of this guy.
That was the last time I ever ran copper for any fuel.
Rich
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