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» ICC Bulletin Board » Code Chat » Plumbing, Mechanical and Fuel Gas Codes » Gas Pipe Material

   
Author Topic: Gas Pipe Material
cbi2
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Is there any reason that you can't use black pipe with galvanized fittings and/or nipples.

Here's the condition: Black pipe in the walls with galvanized fittings. It transitions out of a soffit (in the garage) with black iron to galvie elbow to galvie nipple to brass shut off to galvie nipple to regulator to galvie nipple to galvie elbow and back into the wall with black iron.
This is in California.

Posts: 131 | From: so cal | Registered: Oct 2003  |  IP: Logged
jbh
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Big Box plumbing.
silly but ok

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cbi2
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Plumber tells me that he uses the galvanized fittings because they are more reliable. I'd have to believe him because I know they cost more and the way we've beat them up on their bids it'd be easy to change them all to black. The question came up from a home buyer that is a chemical engineer. He said that you can't mix metals in gas piping. I know it's not a code issue and he agreed but said that it was a metallurgy issue.
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beach
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I would think since the steel pipe is coated with zinc (galvanized) it is already "mixed"...it would react with itself. I don't think it's dissimilar metals. The threads aren't galvanized where you connect the black pipe to the galvanized fitting anyway.

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Uncle Bob
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cbi2,

Galvanized pipe is steel pipe covered with a protective coating of zinc that greatly reduces its tendency to corrode and extends its life expectancy;

except that;

Galvanized steel pipe and fittings cannot be used for gas lines because natural gas causes the zinc to flake off and clog the system.

Refer to pipe manufacturer for confirmation,

Uncle Bob

[ 08-19-2009, 07:25 PM: Message edited by: Uncle Bob ]

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Mac
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Check with the gas service provider - around here, the Gas Co. "terms of service" will not allow it.

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dsjtecserv
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The IRC says:

G2414.4.2 (403.4.2) Steel. Steel and wrought-iron pipe
shall be at least of standard weight (Schedule 40) and shall
comply with one of the following:
1. ASME B 36.10, 10M;
2. ASTM A 53; or
3. ASTM A 106.

The Scope of ASTM A 53:

1. Scope

1.1 This specification covers seamless and welded black and hot-dipped galvanized steel pipe in NPS 1/8 to NPS 26 [DN 6 to DN 650] (Note 1), inclusive, with nominal wall thickness (Note 2) as given in Table X2.2 and X2.3. It shall be permissible to furnish pipe having other dimensions provided that such pipe complies with all other requirements of this specification. Supplementary requirements of an optional nature are provided and shall apply only when specified by the purchaser.

Also see IRC 2415.5. The code fully includes galavanized pipe among the piping materials that can be used for both natural gas and LP systems. There is no basis for supposing that natural gas causes the zinc coating to flake off. Obviously, if the specifc conditions in a particular installation create a unique hazard, that needs to be accounted for, but there is no across-the-board prohibition on the use of galvanized pipe for fuel gas applications.

Dave

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Uncle Bob
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" The code fully includes galavanized pipe among the piping materials that can be used for both natural gas and LP systems."

R102.4 Referenced codes and standards.

Exception: Where enforcement of a code provision would violate the conditions of the listing of the EQUIPMENT or appliance, the conditions of the listing and manufacturer's instructions shall apply.

IRC, Chapter 2 Definitions;

EQUIPMENT. All piping, ducts, vents, control devices and other components of systems other than appliances that are permanently installed and integrated to provide control of envioronmental conditions for buildings.


"There is no basis for supposing that natural gas causes the zinc coating to flake off."

http://www.keidel.com/mech/pvf/pipe-galvanized.htm

and,

http://www.steel-pipes.net/galvanized-steel-pipes.html

Natural gas causes the zinc to flake off and clog the system.

Uncle Bob

[ 08-20-2009, 09:57 AM: Message edited by: Uncle Bob ]

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Putting back my e-mail address; osoros@hotmail.com (ps. my real name is not "Bob Hamilton"); just in case I find that I am not a "valued member". :(

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dsjtecserv
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Bob:

Referencing the web site of a plumber or even a web portal for the steel industry in India does not override the provisions of the code. As is clear form the references I gave, the code fully anticipates the use of galvanized pipe for gas applications, and it has been used for that, throughout the country, for years. Unless a specific code provision prohbits the pipe, either in general or for a specific application, or the manufucturer's instructions for the appliance involved or for the pipe involved specifically prohibit it's use for the gas piping system, then there is no basis for disallowing it.

The notion that natural gas somehow makes galvanizing flake off is an old wives tale that has been circulating in the industry for years; it's not surprising that it circulates more efficiently on the internet. But the fact that you can find someone to repeat it on the internet makes it no more true than it ever was, which is to say, not at all. I'm not quite sure why you felt that the web page of a local plumbing supply or for the Indian steel industry override the ICC codes...

Dave

[ 08-20-2009, 10:15 AM: Message edited by: dsjtecserv ]

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Uncle Bob
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How about you providing an American manufacturing company that manufactures galvanized steel pipe?


"Referencing the web site of a plumber"

Keidel is not a plumber; but, a wholesale distributer of plumbing supplies.

http://www.keidel.com/about/services.htm

I have over 30 years of installing, replacing and repairing gas pipe lines and gas appliances; and I'm not an old wife; I'm a Licensed Master Plumber.

When we had manufacturer's of galvanized pipe in the U. S.; they too warned of using this pipe for natural gas.

Uncle Bob

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Putting back my e-mail address; osoros@hotmail.com (ps. my real name is not "Bob Hamilton"); just in case I find that I am not a "valued member". :(

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dsjtecserv
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We don't need to prove anything. The code is quite clear about what is permitted, and galvanized pipe is permitted. Unless some exclusion reaches that, there is no basis for disapproving it. You haven't cited anything that would override the code provisions. What you were told or choose to believe has no bearing on that.

We agree that if in some case the terms of listing or manufacturers instructions for a particular product contains such an exclusion, it should be honored. However, there would be no difficulty in finding another appliance or pipe that contains no such exclusion.

At this point I think the information needed for code officials operating in good faith has been provided.

Dave

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texas transplant
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Agree with Mac. Use to work in a jurisdiction that the gas utility prohibited galvanized piping in any structure they served. Reason? They said their gas had chemical properties that caused the piping to flake and clog the system. Not saying that IRC prohibits, but there are other players in this game.

They also prohibited the use of copper as Section 403.4.3 of the IFGC 2006 talks about.

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Paul Sweet
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Might this be concern left over from the days of manufactured gas?
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cbi2
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I have heard that in other parts of the country the moisture content in the gas is higher. That is where the "drip leg" came into play.
I don't think that we have that issue.

For the record. Where we penetrate the building with a nipple to the exterior, we always use galvanized pipe. Also the nipple that the "GAS COMPANY" the service to is galvanized. I'm pretty sure that SoCal Gas has no issue with galvanized pipe.

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dsjtecserv
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Paul:

When I was in the natural gas industry we pondered where this came from, and that was one of the theories. Manufactured gas, essentially being the flue gases from incompletely combusted coke, contained all sorts of stuff, including potentially corrosive sulfur compounds and moisture. Since both a corrosive agent AND an electrolyte (e.g. water) need to be present, this was plausible. The problem with it is that the mixture would be no less corrosive to other forms of carbon steel pipe. The myth is that zinc is somehow selectively flaked off of the inside of the pipe, and that phenomenon isn't explained by something that is generally corrosive.

The same logic could apply to some sources of natural gas, known as sour gas, that contain a high percentage of condensable fractions, including sulfur compounds. But the that theory suffers from the same problems as for manufactured gas, and anyway, these days nearly all pipeline gas is processed to remove the condensables (they are valuable in separate markets) and it is rarely an issue in any utility-supplied gas. The only instance where sour gas is a significant concern is when a portion of well gas is diverted to serve the property owner, as part of a mineral rights deal.

To our knowlege no one in the industry was able to cite any credible case where the zinc of galvanized pipe flaked off and clogged or damaged any downstream equipment as a result of exposure to any particualr gas. It's not impossible that that there were some historical cases, either with primitive sources of fuel gas or with earlier pipe that had poor galvanizing, but there isn't any evidence of this being a problem for a long, long time. The National Fuel Gas Code, and the ICC coverage which is derived from the NFGC, have, for as long as I can remember, included galvanized pipe among those that can be used for fuel gas.

Dave

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Uncle Bob
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cbi2,


Third page from bottom;

Figure VIII-21 galvanic corrosion.

"The galvanized elbow will act as an anode to steel and corrode. Do not install galvanized pipe or fittings in a system if possible. However, when using galvanized fittings, the fittings, [b]

http://www.phmsa.dot.gov/staticfiles/PHMSA/DownloadableFiles/smalllpgas-chapt8.pdf

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Uncle Bob
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cbi2,

" Black pipe in the walls with galvanized fittings. It transitions out of a soffit (in the garage) with black iron to galvie elbow to galvie nipple to brass shut off to galvie nipple to regulator to galvie nipple to galvie elbow and back into the wall with black iron."


Third page from bottom;

Figure VIII-21 galvanic corrosion.

"The galvanized elbow will act as an anode to steel and corrode. Do not install galvanized pipe or fittings in a system if possible. However, when using galvanized fittings, the fittings, must be electrically isolated."

http://www.phmsa.dot.gov/staticfiles/PHMSA/DownloadableFiles/smalllpgas-chapt8.pdf

Maybe this old wives tale was started by the U. S. Department of Transportation Pipeline and Hazardous Materials Safety Administration (PHMSA).

Hope this helps,

Uncle Bob

[ 08-22-2009, 08:06 AM: Message edited by: Uncle Bob ]

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Putting back my e-mail address; osoros@hotmail.com (ps. my real name is not "Bob Hamilton"); just in case I find that I am not a "valued member". :(

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dsjtecserv
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Bob:

It helps if you understand the context of documents you cite. The Department of Transportation regulates the gas pipeline system, including the distribution of gas by utilities. This document is a guide for small operators (a typical example is trailer parks) that fall under the jurisdiction of DOT but don't have the resources of large utilities.

The section you cite is dealing with galvanic corrosion protection of underground gas mains and service lines. In underground applications moisture is present to act as an electrolyte, and the chemistry of the soil further influences the potential for corrosion. Consequently nearly all metal pipe must be coated when underground so that the metal cannot electrically contact the ground, and the system may also need cathodic protection, which essentially diverts corrosion away from any exposed anodic portion of the system and instead provide a sacrificial anode.

Corrosion is a big issue with all types of underground metallic systems, and this document is a discussion how to avoid it. It is not discussing a unique problem with galvanized pipe, but just one example of how a corrosion cell can be set up when using different metals in combination. The same rules could (and do) apply to other underground metallic systems, including water lines; this has nothing to do with natural gas.

The document does not cite any problem with the zinc "flaking off" galvanized pipe. It is only concerned with corrosion, which can happen with any metallic underground system. In fact, the very passage you quote makes it clear that the problem is not actually the use of galvanized pipe, but rather the need to electrically isolate it when used underground.

In short, this whole document, including the section you cite, has nothing at all to with the situation at hand, or anything at all do do with any building code.

-It deals with utility system regulated by DOT, not building codes.
-It deals with underground mains and services, not aboveground customer piping, which is what the original post was about.
-It deals with corrosion in the presence of moisture and soil chemicals, not piping system that are in air and lack an electrolyte.
-It deals with corrosion, not the mythical "zinc flaking" phenomenon that you are trying to defend.
-The statements made would apply to any underground system made of a variety of metals and serving many purposes, and are not unique to natural gas.

So, the bottom line is your post doesn't respond to the original poster nor to your original contention that zinc flakes off in the presence of natural gas. I'm not sure why you are going to all this trouble, since what the codes says is clear and incontrovertible. You could of course, work to change the code, but to do so you'll need to make sure that the evidence you cite is relevant to the issue, which your latest post was not.

Dave

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Uncle Bob
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Perhaps, this is where the confusion is steming from. State regulations and Gas company regulations that prohibit the use of galvanized pipe and fittings below ground.

Uncle Bob

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dsjtecserv
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Galvanized pipe isn't exclusively prohibited below ground by either federal regulations nor the code. The problem discussed in the document you cited had to do with dissimilar metals in contact with each other. If the system were composed of ALL galvanized pipe that problem wouldn't exist. However, there would still be a need to protect the galvanized pipe from corrosion, just as there is for any steel pipe. The pipe would need to be coated and/or protected by a cathodic protection system, as discussed in the document.

The building codes have the same attitude, although they aren't as specific. For instance see section 404.8 in the 2003 IFGC. (I don't have the current IFGC or IRC at home, so the number may be different). This states that galvanized pipe is not excluded for use underground, but the galvanizing by itself cannot be considered adequate protection from corrosion. The code doesn't give much more information about how adequate protection is supposed to be provided, but the same techniques described in the DOT document could be used.

So again, corrosion protection is a big issue that is applicable to all metals to one degree or another, especially when used underground. But that's not directly relevant to the original question.

Dave

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Uncle Bob
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I've found the following on several Gas Utilities websites;

Page l2; under, B Fuel Lines (Piping beyond the gas meter).


Page 14; d. Steel Pipe. "Galvanized pipe not permitted." for underground installation.

http://www.oru.com/documents/NaturalGasInstallationStandards.pdf


and, This Utility doesn't allow galvanized pipe to be used in house piping (below or above grond);

page 10 "Modifications to National Fuel Gas Code."

"2. The company does not accept zinc coated or galvanized pipe or fittings."

http://www.duke-energy.com/pdfs/YBHandoutHP.pdf



and, the Texas Railroad Commission; which regulates gas lines;

Page 25; 1330 PIPING.

(e) The following components or materials shall not be use:

(3) Galvanized pipe and fittings.

http://www.propane.tx.gov/publications/cng-lng_regulation.pdf

Why are they prohibiting the use of galvanized pipe?

Uncle Bob

[ 08-22-2009, 12:47 PM: Message edited by: Uncle Bob ]

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hearthman
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Possibly if they know the analysis of their gas as having hydrogen sulphide >0.3 grains per 100cu.ft.

If they have 'wet' gas, they are obligated to disallow incompatible materials. Note they also excluded copper tubing in some of the above stds.
Hearthman

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jbh
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Uncle Bob,
Great info. Thanks.

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dsjtecserv
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Bob, you'll have to ask them why. As you have found through your internet searching, such examples are hard to come by; their scarcity pretty much demonstrates that galvanized pipe is generally accepted, and exceptions require special provisions. They may have good reasons, such as local conditions or the nature of their gas supply, or they may be operating off of the same mistaken assumptions as you have found elsewhere on the internet.

A couple of observations:

Orange and Rockland requires that all underground steel pipe be factory-coated, as does the code. Galvanized pipe is not available factory-coated, and as the code says, galvanizing by itself is not adequate for corrosion protection. So their provision is simply repeating the same thing the code already says for underground piping, in more explicit terms.

Duke apparently also doesn't accept copper pipe and tubing, which puts them well outside the mainstream; copper has been in standard usage for years. It would be interesting if you were to contact them for their rationale and report back. I wouldn't be surprised to find that they inadvertently stated a rule meant to apply to underground pipe in a way that makes it apply to all customer piping.

The TRC document you cites pertains only to CNG and LNG -- in other words essentially industrial applications. The document applies neither to standard pipeline natural gas systems nor to LP gas systems. Now, they may or may not have similar provisions for natural and LP, but this document doesn't provide evidence of that.

Regardless, other posters have already noted that some utilities won't connect to systems using galvanized pipe, so this isn't big news. Whether for good reasons or bad reasons, we should respect the utility's rules in those cases, and galvanized pipe should not be used in those cases. On the other hand, the original poster has already noted that this is not an issue in his area, served by Southern California Gas, so even that point is moot for the case at hand.

It must be said again: there is no general technical reason for prohibiting galvanized pipe and in fact no general prohibition on the use of galvanized, and the code clearly permits its use. Those are the things that matter to code officials who are concerned with enforcing the code in good faith.

Dave

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rjj
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Some real good points Dave! The code permits it and unless the gas supplier prohibits it use problem solved.
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