Pardon????? Galvanize is Zinc applied to steal to prevent corrosion, and the layer of zinc between two pieces of steel will NOT cause any corrosion.
And here in Ontario, far from the west coast, Galvanized piping is no longer forbidden in gas piping.
I'd still recommend non-galvanized if possible - and most real hardware and farm supply stores will still carry "black iron" (maleable iron) fittings.
YOur BS meter needs recalibrating. The ZINC may corrode, but that is not an issue here. It is a very thin coating on one surface that is beinf threaded to another (identical) surface. NOT an issue. Period.
And a welded seam pipe is going to be an issue at less than 5 PSI pressure in natural gas distribution, and not be an issue at 60+ psi in a water system????
There are only a few suppliers of both black and galvanized pipe in Noth America, and a very large proportion of both is "imported - mostly from China. Doesn't matter who you buy it from, or at what price, the chances are very high you are buying the same product.
Why would the zinc corroding not be an issue? If you have a galvanized pipe and the coating is compromised in any way, the corrosion will be concentrated at that point, right? Why do gas companies and many codes prohibit using galvanized fittings in gas lines? Why do you feel that your apparently Pope-like-infallible opinion of your opinion is at issue with those utility companies and AHJs? You are familiar with sacrificial anodes, of course, and you do understand that the more reactive metal will corrode more quickly in a mixed metal situation, and you do know that not all gas is totally pure, may contain water, that there are recommendations for having traps to catch the water, but that the traps are not always present - so why the blanket certainty over a very uncertain situation? Oh, right - it's not your house.
Here's a possible repercussion that makes your opinion moot. A home inspection. If a home inspector flags a galvanized fitting as being against code, the homeowner will end up paying for it, and it will be more than just the price of the fitting. The OP's theoretical attempt at saving himself a trip to a more fully stocked supply house will cost him more in the long run. Perhaps you're banking on the OP being dead at that point, and it no longer being his concern, but I don't take such a short-term view of the situation. :)
I am not saying that the potential problem with using a galvanized fitting or whatever is necessarily a serious problem, nor is it inevitable, simply that there is NO benefit to mixing galvanized and black iron and it will raise concern, and increase the risk of a problem, no matter how small that risk is.
So, to sum up, there is NO benefit - the galvanized costs more, it will bother some people and some of those people are in a position to tell you what to do with your house. So what exactly is your reasoning that it's better to go with galvanized?
RRicodJour wrote: ...
Because there was some evidence that impurities in gas could lead to interaction with galvanizing leading to some particulate contamination.
Once there, as with most Codes, it's much easier to retain than remove restrictions whether they're still needed or not.
As noted above, PG&E did extensive study and determined it didn't seem to be an issue of concern at the time; what that study didn't do was make the decision as to whether to change policy or not. Whether that happened or not subsequently, I don't know. But, the issue wasn't related to this sidebar argument as to why galvanized was/is not used w/ NG.
--
first mistake, you were looking for plumbing at a big box store.
Jimmie
Just check the local code, and go by that. See if it's all black pipe now. If I knew black pipe was code, I'd use black pipe. I put a galvanized gas pipe run in my first house in Chicago when I working in the basement. Had just re-piped all the water and had plenty of galvanized left over. Sometime later a gas worker was in and spotted it right off. Think it was an appliance guy when I bought a new dryer. He said, "You do that?" I said "Yep." "Why'd you use galvanized?" "That's what I had." He could see my pipe bench. Nothing more was said. Always assumed he asked because galvanized was more expensive and not necessary. Who knows. I don't know what code is here, but I put a new HW tank a couple years ago, and had to replace a gas nipple with a longer one. Used galvanized, didn't think anything of it. I just looked and see a lot of galvanized Tees and 90's on the gas piping that were already there. Now I'm pretty sure I'll never check the code.
--Vic
The only zinc that could be an issue at all is inside the pipe or in the joint, where it is protected - no oxygen available.
If it corrodes on the outside, so what? It's just like black iron.
They don't (all) prohibit it. It can be used here. There are a couple of galvanized fittings in my gasline, as well as brass valves.
It's not, as noted above.
Code REQUIRES the drops - and it is NOT for water. It is to allow any particulates to drop out at the LAST bend before entering the appliance. The particles could block a jet - and that would cause problems. That particle COULD be rust, or flaked off zinc from inside either black iron or galvanized pipe. Water in the gas would be a reason to REQUIRE zinc, not to ban it.
Not at all. As I said, where I live the prohibition against galvanized fittings has been removed, for quite a few years now. If you have the REQUIRED drop trap any possible particulates will be caught - and the probability/possibility of a galvanized fitting ot pipe causing a problem is no higher than that of black pipe. The prohibition against Galvanized goes back to "producer gas" or "coal gas" which was the common municipal gas supply for many years, particularly in the east.
First of all, I NEVER said it was BETTER to go with galvanized. I just said if he could not get a black fitting there was no HARM is using galvanized. I even said any REAL hardware store or farm supply would have the required fitting.As in the black iron, or maleable iron fitting. You are just being arguementative, and your reading comprehension is not up to par.
On 1/22/2011 1:08 PM RicodJour spake thus:
This still makes no sense to me. (And just for the record, whenever I've plumbed for gas I've used black pipe, not galvanized.)
I mean, with black pipe, the entire goddamned pipe and every fitting is subject to corrosion, right? Except for the mill scale, or whatever constitutes the "black" on black pipe, it's completely unprotected. That's why we use galvanized for water. So if you use a galvanized fitting on a run of black pipe, it sure as hell is not going to corrode any faster than the rest of the pipe, so why sweat it *on that basis*?
There may be other reasons not to use galvanized with gas lines: all the pros I've talked to about this lately tell me it makes no difference. Nonetheless, most people still use black for gas.
On 1/22/2011 11:01 AM Jon Danniken spake thus:
As I recall, eHow is basically just a web "scraper" that copies content from Wikipedia (another notoriously unreliable source) and republishes it, confirming what Jon just wrote.
In my reply to the OP's question, the first reply in this thread, I wrote, "This is one of those questions that starts wars. Left coasters generally can use galvanized, but I believe that is a different galvanizing process for gas pipe than the standard galvanizing. Something about the galvanizing flaking off or some such. East coast generally has galvanized prohibited. Obviously your local code rules. " Is that what you are arguing about?
I'll tell you what, I'll get the local gas utility company, and the local municipalities that are within the OP's and my area (we're about
15 or 20 miles from each other, and there might be five or six different individual codes for the municipalities between the two of us), to change their codes if they don't accept galvanized pipe, just based on the say so of some guy in Canada. Will that be acceptable to you?I'm answering the OP's question and you're arguing how many angels can dance on the head of a pin. Big help.
R
Local codes rule.
At one time it was prohibited in this area and now it is fine.
If you don't know the local code, I would find a black fitting somewhere.
I have used them in a pinch in the past and never experienced any of the dour predictions I have seen expressed in this thread. I should add that I own the same houses now that I did 20 years or more ago.
To add to that. The "zinc" on the galvanised never touches the "black iron". Threading removes the zinc plating in that area and the fittings never screw together far enough for the zinc to touch the unplated pipe/fitting.
Harry K
I asked this question of my mechanical engineering mentor nearly ~35 years ago. He's long gone & I have mixed installations that has been in service for over 30 years.
He's comment to me back in the 70's was........
"The myth that natural gas causes galvanizing to flake off is an old wives tale that has debunked by testing, go ahead and use it"
Here is a link to pretty detailed thread on the subject, including cites from the IRC.
a couple guys go back & forth but I'm putting my money on the IRC, posts in the cited thread by dsjtecserv & my mentor. He had YEARS of industrial mechanical engineering experience, including being the chief engineer on design & construction of a natural gas to fertilizer plant.
YMMV but has been pretty good so far :)
cheers Bob
To the above I would add that the comparison to the boat use of zinc as a sacrificial anode is invalid, unless the pipe in question is being used in an environment where it's EXPOSED TO AN ELECTROLYTE. The electrolyte essentially completes a circuit that allows current to flow. In the case of boats, that electrolyte is water, or even worse, salt water. With the boat, you have sacraficial zinc plates electrically bonded to the underwater metal parts, ie shafts, props, struts, etc. The circuit looks like two different metals, ie bronze and zinc, sitting in a beaker of salt water. Very similar to the experiment kids can do, using a lemon, a dime, and a penny to make a battery. As the current flow, the zinc erodes and slowly disappears.
With galvanized pipe installed on a gas line indoors, you don't have an electrolyte. If it were buried, then you could have an issue. But buried you have an issue with black steel too. I think it's still being allowed in some areas. But it's supposed to be coated and or wrapped with tape to prevent corrosion. A process that is far from perfect. I've seen black steel pipe fail underground in as little as five years. It looked like swiss cheese, hard to believe. But it was obvious what had ocurred. You could see where the installers had used black pipe and then poured the tar like coating over the top of it after it was installed in the trench. The bottom portion did not get coated and that is where the failure ocurrred. I remember at the time, mid 90s, we had the gas company involved in recommending what to do at a 120 unit condo. At that time even they were undecided which was better for that application, either black pipe correctly installed or galvanized. Today, for corrosion issues, plastic is now widely used underground.
Over the years gas companies have looked at ALL the issues, including not only what the pipe is carrying, but where it is being used. The only potential problem with galvanized that I've ever seen documented in any way is that which DPB brought up, which is the concern that certain impurities in the gas could lead to the zinc flaking off and ultimately clogging orifices, etc. I don't believe it was ever an issue of the pipe failing, leaking, etc. If galvanic corrosion were a real issue with gas pipe in an application inside a house, the gas companies that allow it would be pretty stupid, no? As would the fire rating, safety, insurance companies, etc.
Well, when I was a kid in the 50s and 60s, someone told me that black iron pipe is used for gas because, when tightening a joint, the pipes grind into one another making a tighter seal. I don't know one way or another .... that's just what I was told. I've heard all the other "tales". The gas (propane) in my new house is neither. It's a corrugated flex line, covered with yellow plasticy rubbery stuff ... looks like yellow heat shrink tubing.
I can not argue with any of that, even though it does poke large holes in my argument. On the plus side - I did get to get in a nice plug for the marine industry. ;)
We've agreed on the following:
- that the IRC and many other codes allow mixing galvanized and black iron pipe in distribution lines
- that there is little likelihood of there being any problems by doing so
- that some local codes and gas utilities prohibit using galvanized pipe
- that it is mandatory that people contemplating using galvanized pipe in gas installations check with their gas utility and/or local code to see if it is permitted.
Now, how do we erase all of the extraneous back-and-forth on the topic on the Internet so people will have a clear, simple grasp of the issues?
R
How can something so simple become so complex? :-)
TDD
Human nature...? Just bring up the subject of helmets on a cycling newsgroup. Everyone is 100% right, adamant about it, and nobody agrees.
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