Copper, gas, and sour gas


Awl --
The issue of copper for natural gas came up recently, where a poster indicated that, according to his city code, a certain **type** of copper was OK. I was not able to find out what that copper was, but then I'm no google whiz.
What I did find some consensus on was the issue of H2S concentration in the gas and copper compatitbility:
Copper is quite OK (apparently any type) IF the concentration of H2S is less than 0.7 grains per 100 cu ft or 0.7 mg per 100 liters ( http://dallascityhall.org/pdf/Building/CopperFuelGasSystems.pdf ) . I think it was this link that indicated that providers are *supposed to* supply "clean gas" with h2s less than this.
I surmised that part of the problem is that a lot of natural gas *aleady* has boucou h2s in it, and the problem is getting rid of it. It's called "sour gas" if the concentration of h2s is high enough.
One guy in http://www.nachi.org/forum/f22/copper-gas-pipe-18350/ talks about copper for gas being fine after 100+ years of use, that he knows of first hand. The discussion in general shows the disparity of views, with some people thinking copper is preferable to black pipe in some regards.
Another less sophisticated discussion is on http://answers.yahoo.com/question/index?qid 081021200400AAVuMX0 .
The copper peeple certainly endorse copper's use: http://www.copper.org/applications/fuelgas/ , and specifically talk about K and L copper tubing.
I may have found an original copper gas line in my 1920's house, altho I have to verify that this line is indeed carrying gas -- my only hint so far is that it is by itself, as opposed to hot/cold water pairs. I guess I'll put a stethoscope on it or sumpn, to try to sleuth this out.
The Q is then: how diligent is the typical supplier about providing clean gas?
Another interesting thing is that you can buy natural gas detectors -- not too expensive, < $100 iirc.
These, in conjunction with a solenoid main gas valve, should provide pretty foolproof protection for any type of gas delivery system. I'm thinking of getting one of these, altho a 2" solenoid gas valve (2" to and from my meter) will likely break the bank. I should proly think about downsizing this -- 1" should more than suffice, I would imagine.
Also, getting a solenoid gas valve to *work* with a detector, or buying a turnkey system, proly isn't so cheap, regardless of the pipe size.
--
EA



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On Sun, 15 Nov 2009 09:29:07 -0500, "Existential Angst"

If there are any questions about the effect of H2S on copper, I would refer you to any of the "chinese drywall" threads. Bear in mind this is at a very low concentration.
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wrote:

FWIW, years ago I ran a flexible copper line to an outbuilding that needed heat. It stayed in service for around 3 years, and was removed. By then the copper was no longer very bendable at all, and the interior was typical dark brown from sulfur reaction. Doesn't seem to me there was any safety issue, since the flexible characteristic of the installation was not a critical element, like compensating for some sort of movement. Logically then, a robust rigid pipe well supported should be OK for a lot of installations. Black iron, though, wins on cost and integrity of the threaded connections. Local pros still install it underground with heavy asphaltic coating wrapped with paper. Of course, newer materials on the market should be considered.
Joe
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Existential Angst wrote:

Since you've discovered the H2S limit for reasonable operation, your next call should be to your natural gas supplier and ask them the H2S concentration they supply.
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