Joining black steel to stainless: which dielectric union?

Understandable! I'm pretty sure what Growler meant was a galvanized ground joint union. (see image) and as In remember,( it's been a long time), I seam to remember that the boss of the union had some brass that made contact for a better joint. So the two IRON pipes would be joiined by a galvanized IRON union. Regards, Tom

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Guess I'm just getting brain dead , see no good reason to run stream into a pipe that will rust when you could use other materials. I think you once told me that it wasn't that long ago when there were no toilet flanges, things keep changing, sometimes even for the better. Its getting more rare to even use black pipe for gas. Must be an age thing.

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This is common in the brewing idustry. The low pressure steam boiler output pipe is black steel. Also, here's a description of uses from McMaster Carr (McMaster-Carr) page 57:
Standard-Wall (Schedule 40) Black Steel Unthreaded Butt-Weld Pipe Fittings

Use with air, water, oil, natural gas, steam
Pipe: Use standard-wall (Schedule 40) black steel unthreaded (see page 58)
Flanges: Use low-pressure black steel unthreaded (see page 58)

So, hopefully it won't just rust the pipe. Any idea why there's a suggestion to add a brass ground joint, when the dielectric union was designed to separate brass from steel? I'm considering proceeding with connecting the black pipe to galvanized components and then the galvanized components to my stainless steel....thanks for the responses
Kevin

YUP kb and speedball...black pipe and steam work fine...no rust...or at least rare. We pipe steam boilers in black pipe all the time...still do to this day. No comment on union fittings..you guys seem to have that covered.

A dielectric union is designed to separate steel from copper, not from brass.

While brass does contain copper as an amalgam, it is not subject to the same level of electrolysis as pure copper.

Look at it this way -- Red Brass is the principal material used in ball valves, check valves and gate valves for both copper and galvanized steel piping systems.

As for your low pressure steam system, if it isn't piped yet and you're still concerned about electrolysis, then plumb it with type L copper and make the connection at the boiler and brewing equipment with a dielectric union.

Also -- You can buy dielectric unions that are FIP on both sides, if you go this route, connect the galvanized steel side of the union to the Stainless Steel inlet of the equipment and the brass side of the union to the Iron Pipe side.

An aluminum companion flange is yet another option.

Well guys you taught me something today. Most or my work is repair and installation, never been around a brewery much but know of its products too well. Thanks,
Bob

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I assume you realize that a union is not the proper item you need by now.

I suggest you use carbon steel 150 RF threaded flange on one side.

A stainless steel rf threaded flange on the other side.

And a flange insulation kit to go in between to stop electrolosis.

This is you're best solution.

Trust me

Call me for a quote 530-222-0423

Thank you,

Josh Brown.
Northern Industrial Sales / JW Wood Co.

Doesn't really matter...use any die-elctric union.It is basically the insulation in the union that keeps the dis-similar metals apart.The Black steel can be threaded and the Stainless Steel can be soldered to brass easily.No sweat!

Hi Nevellens....

Thanks for posting but please note the dates of the threads you post to as in this case the thread goes back to 2008...

Mark