Can galvanized fittings be used with black iron pipe?

Page 2 of 3  


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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Jan 23, 7:48 am, snipped-for-privacy@optonline.net wrote:

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 1/23/2011 9:27 AM, RicodJour wrote:

How can something so simple become so complex? :-)
TDD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Human nature...? Just bring up the subject of helmets on a cycling newsgroup. Everyone is 100% right, adamant about it, and nobody agrees.
R
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The Daring Dufas wrote:

a zillion different sets of rules?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Use Google. Erase.......
it is similar to Google.Takeback (what you use when you want retrieve an email or posting that you wish you hadn't sent.)
cheers Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
DD_BobK wrote: ...

Can't help; once a posting hits usenet, it's gone. Virtually no servers honor cancel messages.
--
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Would that it were so. That only works with Google posting, right? I'm talking about all of the forums and sources out there where this topic comes up repeatedly and the same information gets batted about. Since we've 'solved' it, we should save other people from having to wade through the extraneous and misleading information. Maybe post a Wikipedia article and just point back to that whenever it comes up here? Post the Wiki link on those other forums?
R
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 1/23/2011 7:27 AM RicodJour spake thus:
[massive snipola]

Like they say, good luck with that!
--
Comment on quaint Usenet customs, from Usenet:

To me, the *plonk...* reminds me of the old man at the public hearing
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 22 Jan 2011 21:22:14 -0800 (PST), Harry K

zinc in the female threaded portion. Not with hot dip galvanizing, for sure - but in "bright zinc" "galvanizing".
This does not change the fact that the zinc is NOT a corrosion risk.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Why in the world would the Chinese use too much zinc in the copper alloy? That would be unethical and greedy. Could never happen. ;)
R
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 1/23/2011 6:26 PM, RicodJour wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 21 Jan 2011 21:58:20 -0800 (PST), RicodJour

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.

hardware and farm supply stores will still carry "black iron" (maleable iron) fittings.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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.
http://www.ehow.com/how_6816090_mix-black-pipe-galvanized-pipe.html
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 1/22/2011 8:39 AM, snipped-for-privacy@optonline.net wrote:

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Jan 22, 9:39am, snipped-for-privacy@optonline.net wrote:

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@optonline.net wrote:

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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.
--
Comment on quaint Usenet customs, from Usenet:

To me, the *plonk...* reminds me of the old man at the public hearing
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.