Was at Lowes tonight picking up stuff for hooking up my HW heater this weekend and found out they did not have anymore 1/2" Tee's in black iron for my gas line. But they had galvanized 1/2" Tee's. Can I mix the 2?
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.
I would not mix galvanized and black iron directly, even if it's allowed, as that accelerates corrosion. You'd have to use a dielectric fitting.
Best thing is to visit a local plumbing supply house for such things. They'll have stuff Lowes and Home Despot won't carry, and the guys know far more than the guys in the aprons. On a side note, the local big guy plumbing supply house, which I used to loathe going to as they had major attitude and you had to be waited on (long lines and attitude =3D I go elsewhere), changed over to a pick-your-own store set up. Far superior. I'm sure they did it to trim superfluous counter people and pickers, and make the store more user-friendly.
ROn 1/21/2011 9:58 PM RicodJour spake thus:
Now *that* makes my BS meter twitch just a mite: why would there be corrosion? Galvanized pipe is zinc over steel, so galvanized + steel (black) should be no problem, right?
To rephrase what you said, if zinc + steel = corrosion, than a galvanized pipe should disintegrate just sitting on the rack.
Black pipe and galvanized pipe are the same material with just one difference: galvanized pipe is coated with zinc to prevent the underlying steel from corroding. Galvanized piping was commonly used in pipes that carried drinking water--before the widespread use of copper piping and PEX tubing. Black pipe was used in drain lines, heating piping and natural gas piping. Black pipe can be used in lieu of galvanized pipe as long as the piping system isn't for drinking water. Since both pipes are basically the same material, they fit together with ease.
It's interesting that they worded it as "black pipe can be used in lieu of galvanized pipe...." and did not state that they are interchangeable, ie the other way around too. Though they seem to imply it. That is the opposite substitution that the poster is asking about. And like Rico stated in the first reply, different areas have different rules regarding the use of galvanized pipe with gas.
I think from a practical standpoint, it's a nit. The theoretical issue is that natural gas can have contaminants which could react with the zinc, form flakes, which can come off and create problems. But, whether today's gas even has that issue I don't know. Nor have I ever heard of it actually ocurring. IMO, you could mix the two if you had to, and it would be fine, but might not comply with local code. I'd just go find the black fitting, which are very common and should be easy to find.
I also think the ehow advice is incorrect in general anyway. First they state that the glavanizing is to prevent corrosion, then they say you can substitute black iron? Suppose the application is outside, exposed to the weather, for example. Galvanized won't rust and need to be painted, black iron will.
I had to hook up a small electric water heater a few years ago and used a combination of short-length galvinized and regular steel pipes and tees near the tank, and used PEX feed lines to and from the tank.
In about 3 years the non-galvinized sections were very rust on the outside, and really badly crudded-up on the inside, creating rusty water if the hot water wasn't used for a few days (this is a small tank - about 3 or 4 gallons). There was even some leaking of these pipes too.
I replaced everything with galvinized and no rust and no leaks for about
2-3 years now.For a gas line, there is some water in natural gas - you're supposed to put in a drop-trap line to catch the water before runs into your appliance so the water can accumulate there. I'd be using galvinized for that if it were me.
Depends on your gas utility. The giant bureaucratic mega company that serves our area will not permit galvanized pipe or fittings.
? "Home Guy" wrote
I'd not bother. I've seen installations that are 50 years old and no problems with black pipe.
The rules and inspectors in my area do not allow galvanized pipe use on natural gas systems. I think in the uniform Southeast building code.
TDD
Time to recalibrate that meter, kimosabe. Zinc is used as a sacrificial anode in boats for the very reason that it will corrode first and protect the iron.
Exactly.
I have no personal experience with galvanized in a gas installation, as I don't do them, and it's not allowed by the code around here. The we(s)t coasters find it hilarious that the East coast codes often prohibit it. I've heard that the galvanized used in gas installations is different somehow, but again, no personal experience.
Like I said, the OP's question is one of those that start wars. Everybody has anecdotal evidence (both ways) as 'proof', and the difference on the subject in otherwise uniform codes makes it suspect to many people.
eHow is often more like eWTF?
R
On second thought, you're right. It will - if you wait long enough.
R
Bingo. I was waiting for someone to chime in with that. It surprises me that people don't notice such things, and assume that all iron/ steel is the same.
I still have no clue what sort of galvanized pipe they use on the other coast and how it differs, or if it differs, from galvanized pipe in the Northeast. Anyone know?
R
ehow is the bottom of the bucket in ad-ridden spam sites; information on ehow is written by idiots who think it's a GRQ scheme. You can pretty much discount anyone linking to ehow as a complete net newbie, who chose ehow because it came up first in a google search (they specifically design the site so it comes up first).
There are a plethora of decent user-generated websites, forums, and even commercial sites that are 100x better than ehow spam.
Jon
Much black pipe is welded as well (ERW, commonly, these days).
It's not the manufacturing process, per se, that determines the ASTM Standard to which any given pipe will meet but the combination of materials and manufacturing and quality control. Welded pipe may meet or exceed a given seamless pipe of similar bore/schedule depending on the intent and/or spec is was manufactured to. IOW, it isn't whether it's welded or not matters, it's the Standard to which it was graded.
There's no difference in galvanized from one part of the country to the other; the only more-or-less definitive study on its application w/ natural gas I've seen (not to say there isn't more; only this is only one I've actually looked at) was done by PG&E who are, afaik, still west coast... :)
It concluded that w/ current domestic gas the impurities that were the initial concern weren't any longer but hedged its bets on the future w/ imports and particularly the possible/probable advent of large quantities of import compressed/lng products.
It was dated sometime in the 90s iirc; I've no idea what might be current Code or if any action was taken. Here in the barren middle NG-producing part, local Code anyway still hasn't been modified other than to accept the newer materials; galvanized is still generally not seen for NG.
For a single fitting in a small line, I'd not worry about it back to the OPs question altho I'm one that it would look out of place so I'd go get a matching fitting just on that basis alone.
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dpb wrote: ...
I'll add that, of course, the obvious answer is to get the matching and that what is kosher for the OP's area/Code is not at all the same thing as whether I'd worry about the effects... :)
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The OP said he was shopping at Lowes. There is only one quality at Lowes and they aim for the lowest selling price. What would you deduce from that about the galvanized pipe they carry? That's a rhetorical question.
RRicodJour wrote: ...
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That there's at least a reasonable chance it's the same that he'd get a stick from at any other local distributor including the "pro's" places...
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