How to connect PEX to galvanized half inch pipe?

[Sprinkler]

Hi, I have a leak in a galvanized half inch pipe, and I want to replace some of this old pipe with pex. I will try to unscrew the 90º elbow (as in photo), and connect the pex directly to the threaded galvanized pipe. The problem is the fittings for pex are brass which isn't compatible with the galvanized pipe, but I have doubts about using dielectric fittings after reading some opinions online. Do you know of some good way to make the connection that would be ok for a potable water supply?

But If for some reason, I can't remove the old elbow, I was thinking of cutting the half inch galvanized pipe and using a coupler (rubber?) fitting to connect to the 20mm pex, but I suspect that those couplers are not approved for potable water? Thanks.

 

[hj]

Brass and galvanized are COMPLETELY compatible, (otherwise we could not use brass valves), so that is not a factor.

 

[Sponsor]

 

[Sprinkler]

Brass and galvanized are COMPLETELY compatible, (otherwise we could not use brass valves), so that is not a factor.

Well, that's good to hear! So, the typical Pex compression fittings (as in the first photo) are fine to connect to Galvanized? And the brass connector (common with copper pipe) in the second photo? And no problem with possible oxidation caused by mixing brass and galvanized? Thanks

 

[Reach4]

You can connect to a threaded galvanized pipe or fitting, but you cannot use a push-on Sharkbite or similar to galvanized AFAIK.

I would want to get to a threaded coupling to connect to the galvanized, even if it means removing more galvanized. Maybe the coupling I describe below is suitable for long term use.

I am slowly replacing galvanized with PEX. If I get to where I need to cut a galvanized pipe, and splice in something, that will only be temporary... so I can keep water going with break time between piping work. Anyway, the one coupling I know that can connect to 1/2 inch galvanized without threading is a "Dresser" type coupling.

I think this is one of the clones of a Dresser coupling: http://www.homedepot.com/p/LDR-Indu...FPT-Compression-Coupling-311-CCL-12/100566707 This is the 1/2 inch version, but they have 3/4 also.

I don't know why they call it an FPT coupling. I think it can connect two iron pipe size pipes, but I had been thinking of putting an appropriated coupling on a piece of schedule 40 PVC (which is IPS). Then grasp that in one side of the coupling, and put the other side on the galvanized pipe.

I think there may be a better way. I would like to hear other alternatives.

It is common practice to connect brass to galvanized.

 

[Dj2]

If you are starting to get leaks in galv pipes, maybe it's time to replace them all with something new, PEX or copper.
Usually, the first leak is not the last one.

 

[Sprinkler]

My preference is to connect that brass pex fitting to the threaded galvanized pipe after removing the elbow, but if I run into problems or damage the threads or whatever, my backup solution is to cut the galvanized and use a (galvanized) connector (as in photo) to connect to the pex. I suppose that connector would be ok, or would it only be a temporary solution?
Also, not possible to re-thread the old galvanized pipe as it's fixed to the wall.
I can't remove all the galvanized as it goes to the neighbours patio - all the apartment block has galvanized, so it's a question of having to join to that old pipe. In any case, as long as the brass and galvanized are compatible and don't cause faster rusting, I'm happy. The pipe inside my patio is covered in white (probably water based) paint, possibly not a great idea, because the same pipes that run through the building are unpainted and look in better condition, as in the second photo.

 

[Reach4]

a (galvanized) connector (as in photo) to connect to the pex.

Do you have a part number or other info for the connector in your photo?

I see a "Galvanized Male Compression Adapter"

 

[Jadnashua]

If you're going to be doing this connection outside where it can be exposed to UV lighting, you MUST cover and protect the PEX from the sunlight, or it will degrade quickly.

 

[Sprinkler]

The pipe repair will be indoor but near a window, so I'll make sure no direct sun gets to the pex. Maybe up to an hour of sun got on the pex during transport from the supplier, hopefully not a problem - it looks ok anyway! I found a link to the coupler fitting that I have, but I'd only install it as a last resort if I can't do a clean elbow removal from the galvanized pipe. So, would this coupler be ok for potable water, and be a reasonably permanent repair?
https://www.amazon.de/Gebo-Armaturen-Temperguss-Klemmverbinder-Zoll-01-150-00-01/dp/B0017VC9VE

The idea would be to connect the pex to the male thread of the coupler

 

[Reach4]

I had sent info on a 3/4 adapter. I don't see that in 1/2 inch at a good price. Click Inbox. http://www.deaconind.com/Customer/DEINSU/specpages/Dress_65.pdf


I am not sure if you would be even getting the right thread or pipe size with the one from Germany. Even if you knew it was 1/2 inch pipe size, it could be British pipe threads. Maybe you could ask. I also sent another link for 1/2 inch, which would have the right size for sure.

 

[Sprinkler]

No, I see that the male thread on the German coupler has the same thread as a 1/2" shut off valve that I'm going to install, so it seems to be correct - the other end that goes over the 1/2" galvanized, I assume is ok, but I'm not 100% sure.
Now I'm wondering if it might be better to use copper pipe instead of pex, in case some sun UV light gets on the pex. I only need to install about 1 meter of pipe. Would 18mm dia copper be more or less equivalent to the galvanized which is around 22mm ext diameter? And would it be ok to connect copper pipe to the galvanized? I mean with the usual brass fitting. Thanks!

 

[Craigpump]

Brass and galvanized are COMPLETELY compatible, (otherwise we could not use brass valves), so that is not a factor.

Not so. I can't count how many times I've seen galvanized pipe/nipples fail when screwed into brass valves or check valves.

 

[Craigpump]

Use a PVC coupling between the brass & galvanized to ensure that the dissimilar metals do not come in contact with each other.

 

[Jadnashua]

Galvanized will corrode and fail, regardless of what you have attached to it. Dissimilar metals, in the presence of an electrolyte, act like a battery, and will corrode...the further apart they are on the reactivity chart, the faster that happens.

 

[Sprinkler]

Use a PVC coupling between the brass & galvanized to ensure that the dissimilar metals do not come in contact

But surely a PVC coupling isn't approved for drinking water? Is there any other kind of plastic coupling that would be more suitable in my case? Or how about a dielectric adaptor? Brass fitting +dielectric+ galvanized?

And as regards the earlier comment about Brass and copper being "completely compatible":

Not so. I can't count how many times I've seen galvanized pipe/nipples fail when screwed into brass valves or check valves.

This is also what I understood from reading in forums, that brass connected to galvanized cause faster oxidation.

 

[Sprinkler]

I had sent info on a 3/4 adapter. I don't see that in 1/2 inch at a good price. Click Inbox. http://www.deaconind.com/Customer/DEINSU/specpages/Dress_65.pdf


I am not sure if you would be even getting the right thread or pipe size with the one from Germany. Even if you knew it was 1/2 inch pipe size, it could be British pipe threads. Maybe you could ask. I also sent another link for 1/2 inch, which would have the right size for sure.

Thanks for the information. I haven't yet dismantled the galvanized elbow, but would I be right in assuming that as the exterior diameter of the galv pipe is around 21 mm (.840"), then the thread on that pipe would be 1/2" ?

 

[Sprinkler]

Referring to the comment about brass and galvanized being "completely compatible"

Well, that's good to hear! So, the typical Pex compression fittings (as in the first photo) are fine to connect to Galvanized? And the brass connector (common with copper pipe) in the second photo? And no problem with possible oxidation caused by mixing brass and galvanized? Thanks

This has me quite confused. In this link https://www.reddit.com/r/askscience/comments/35ypgu/why_do_plumbing_dielectric_unions_always_fail/, someone says that brass to galvanized is no problem, but that a dielectric union fails within maybe 5 years. And some suggest that dielectric unions fail if they are over-tightened, causing metal to metal contact?
Now I'm thinking of connecting from the galv. pipe to copper pipe - I think the copper pipe fittings are brass? The doubt I have about PEX pipe is that it should only be used where there is no UV (natural) light, so basically only in darkness?

 

[Craigpump]

But surely a PVC coupling isn't approved for drinking water? Is there any other kind of plastic coupling that would be more suitable in my case? Or how about a dielectric adaptor? Brass fitting +dielectric+ galvanized?

And as regards the earlier comment about Brass and copper being "completely compatible":

This is also what I understood from reading in forums, that brass connected to galvanized cause faster oxidation.

 

[Craigpump]

We use sch 80 PVC everyday for drop pipe when we set pumps

 

[Sprinkler]

We use sch 80 PVC everyday for drop pipe when we set pumps

I see that according to the NYS plumbing code (I think from 2005) that copper pipe must be connected to Galvanized steel pipe, by using EITHER a brass fitting OR a dielectric fitting (with fitting "screwed to pipe")

See section 605.23.1
http://www2.iccsafe.org/states/new_york/NY_Plumbing/PDFs/Chapter 6.pdf

But I have read different opinions about the correct way to join brass and galvanized steel, so it can be a bit confusing...

Oh, I just saw the same information about connecting copper to steel via brass according to NYS plumbing code (from 2014) in this link: (top of page)

https://up.codes/search?previous_pu...q=galvanized&category=new_york_city&year=2014
section: 605.24.1