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Old 02-26-2010, 02:19 PM   #1
FastKat
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Default Can you mix brass, steel, and aluminum pipe fittings?

I am running transmission fluid cooler lines between my trans and an aluminum cooler. I am trying to do it on a budget, which means shopping at Fastenal and the hardware store instead of Summit.

Anyway, I found all of the fittings I need but some are steel, some are brass and some are aluminum. I am using steel brake line to make the hard lines, and trans-fluid approved rubber hose (nylon/whatever that stuff is) to make the soft lines. Can I mix the aluminum, steel and brass fittings together?

(The stuff actually fits together, I just want to make sure they won't corrode each other, vibrate apart, damage my transmission, or cause other unforeseen problems.)

Thanks, -Dave
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Old 02-26-2010, 05:43 PM   #2
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Default Re: Can you mix brass, steel, and aluminum pipe fittings?

I myself prefer not to mix steel & aluminum fittings due to corrosion. I'll do it if needed, but I'll use a good thread compound.
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Old 02-26-2010, 07:41 PM   #3
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Default Re: Can you mix brass, steel, and aluminum pipe fittings?

Thanks! I don't think I have any steel on aluminum directly - only steel on brass and aluminum on brass.
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Old 02-27-2010, 10:40 PM   #4
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Default Re: Can you mix brass, steel, and aluminum pipe fittings?

If you mix different metals can get what is called electrolysis (spelling). This is due to flow of the material in the pipe/tubing. You can cause corrosion on stainless when attached to steel piping if you do not install an isoalation kit between the two metals.

I don't think you will create enough flow to cause this issue but as mentioned use pipe dope/sealing tape.
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Old 02-28-2010, 06:43 PM   #5
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Default Re: Can you mix brass, steel, and aluminum pipe fittings?

They used to sell magnesium bobs that you would put in your radiator as the sacrificial anode, if that's what you call it. Much like the zinc blocks they bolt on propeller shafts to save the bronze.

International Auto Parts used to have them.
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Old 02-28-2010, 08:38 PM   #6
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Default Re: Can you mix brass, steel, and aluminum pipe fittings?

Steel and aluminum is one of the worst combinations. If the connection is exposed to any weather don't do it. Pipe dope like plinker says can help but you'll still create a battery and eat away your fittings. Research galvanic corrosion on the web.
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Old 03-01-2010, 12:24 AM   #7
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Default Re: Can you mix brass, steel, and aluminum pipe fittings?

A timely thread!

I was going to ask about brass valves at the end of my galv. steel pipe for my compressor system. I wonder how much of a factor this would be? Also maybe nickel plated brass valves instead, to galv. steel pipe.
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Old 03-01-2010, 03:27 PM   #8
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Default Re: Can you mix brass, steel, and aluminum pipe fittings?

Vinko
The rule is ANY dissimilar metals will create a charge between themselves and generate electricity while eating away at one of them. But the steel/zinc (galvanised) and brass combination is not bad at all. The effects are minimal in my experience and you see it all the time in home heating systems. Again, aluminum and steel is bad, one of the best places to see the effects of this is a 70's aluminum boat motor block and then look at the condition of the steel head bolts (thats even with the use of a sacrificial anode) RE: Daniel Dudleys post. More bad, steel nails in copper flashing or steel nails in aluminum flashing. Any water or salt water makes this worse. I found SS steel works well against aluminum even in marine applications, but it does degrade in time.
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Old 03-01-2010, 07:28 PM   #9
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Default Re: Can you mix brass, steel, and aluminum pipe fittings?

Re: copper and steel

25 years ago I re plumbed my house with copper pipe. I drove 3 1/4 inch nails into the joists and lay the copper on the nails to get it all laid out in the right plane and with straight runs. Once I had it all in the right place, I tied it down with copper straps and pulled the nails. I missed one and last year the pipe let loose spraying water everywhere. Once I tracked it down, I found where the pipe was resting on the nail. There was a coroded hole in the copper pipe right where it was touching the nail. This is in a fairly dry basement. It was not abrasion. The edge of the hole was green with the coroded copper.

Brian
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Old 03-01-2010, 07:39 PM   #10
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Default Re: Can you mix brass, steel, and aluminum pipe fittings?

Steel and alum, depending on the types, should be okay under certain conditions. I don't think either with brass wouldn't go over too well.

Google for a anodic compatibility table or galvanic series table to see the proximity of the metals to each other. The further away they are, the greater likelihood of corrosion.
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Old 03-07-2010, 04:12 PM   #11
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Default Re: Can you mix brass, steel, and aluminum pipe fittings?

Quote:
Originally Posted by Stuey View Post
Steel and alum, depending on the types, should be okay under certain conditions. I don't think either with brass wouldn't go over too well.

I disagree.
Alum has a high dielectric potential. It will be a problem in lots of applications. That said, with proper treatment, it is extensively used in flight critical systems of aircraft.
Brass and copper are good in just about any application. While you might see some discoloration, they won't swell and seize and fail like alum will.
On an oil cooler, with proper quality of fittings, you should be good. Just make sure you are using proper AN alum and not some crap you found at Autozone.
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Old 03-08-2010, 06:43 AM   #12
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Default Re: Can you mix brass, steel, and aluminum pipe fittings?

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Originally Posted by buildyourown View Post
I disagree.
Alum has a high dielectric potential. It will be a problem in lots of applications. That said, with proper treatment, it is extensively used in flight critical systems of aircraft.
Brass and copper are good in just about any application. While you might see some discoloration, they won't swell and seize and fail like alum will.
On an oil cooler, with proper quality of fittings, you should be good. Just make sure you are using proper AN alum and not some crap you found at Autozone.
I know alum is typically horrible, but according to its avg properties, it may be okay sometimes. I still don't see why a steel-alum loop would be too bad. I am only tryng to suggest that alum or steel with brass or copper would be far worse.

In a computer watercooling setup, mixing copper and alum in a waterloop will often lead to horrific corrosion, sometimes even if strong inhibitors are used.
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Old 03-11-2010, 05:52 PM   #13
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Default Re: Can you mix brass, steel, and aluminum pipe fittings?

Mate your fitting of like metals together and when you need to change metals do it through the soft line. AL of on end SS on the other. This has worked before for me without any leaks of problems yet.

I wouldn't think that direct mounting copper to a dissimilar metal would be a problem, however there are other here saying it is. Err on the side of caution. The cost difference shouldn't be too bad.
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Old 03-14-2010, 04:08 AM   #14
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Default Re: Can you mix brass, steel, and aluminum pipe fittings?

Quote:
Originally Posted by stewart View Post
Vinko
The rule is ANY dissimilar metals will create a charge between themselves and generate electricity while eating away at one of them. But the steel/zinc (galvanised) and brass combination is not bad at all. The effects are minimal in my experience and you see it all the time in home heating systems.
Thanks for the info. I'll look into this a bit further. Maybe go with nickle-plated brass valves, but research will be needed on my end here
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Old 04-29-2010, 02:46 PM   #15
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Default No problem.

Quote:
Originally Posted by FastKat View Post
I am running transmission fluid cooler lines between my trans and an aluminum cooler. I am trying to do it on a budget, which means shopping at Fastenal and the hardware store instead of Summit.

Anyway, I found all of the fittings I need but some are steel, some are brass and some are aluminum. I am using steel brake line to make the hard lines, and trans-fluid approved rubber hose (nylon/whatever that stuff is) to make the soft lines. Can I mix the aluminum, steel and brass fittings together?

(The stuff actually fits together, I just want to make sure they won't corrode each other, vibrate apart, damage my transmission, or cause other unforeseen problems.)

Thanks, -Dave
Stuff like that is done all the time without problem. When I installed a remote trans filter on my F-150, I threaded steel fittings into the aluminum filter head, then brass hose barbs into the steel fittlings. This was done 4 years ago and is still problem-free.

If you look closely at the air brake systems on highway trucks, you'll notice steel & brass fittings are commonly threaded directly into the aluminum valves.
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Old 04-29-2010, 03:56 PM   #16
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Default Re: Can you mix brass, steel, and aluminum pipe fittings?

Are you sure brake line is large enough inside diameter for a tranny cooler?
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Old 04-29-2010, 10:42 PM   #17
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Default Re: Can you mix brass, steel, and aluminum pipe fittings?

When faced with the abundance of theroy put forth here, you need only to look at a typical transmission cooler/radiator combination on any production car:

Transmission case: ALUMINUM
Adapters to go into the NPT threads on the ALUMINUM case to provide female flare fittings for the cooler lines: BRASS
Flare nut on cooler line: STEEL
Cooler line: ZINC coated STEEL
Flare nut on radiator end of cooler line: STEEL
Female fitting in radiator tank: BRASS

So, as you can see, a typical passenger car utilizes the very combinations of dissimilar metals that you guys say won't work.
Someone should call Detroit right away and get this straightened out.
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Last edited by tcianci; 04-29-2010 at 10:45 PM.
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Old 04-29-2010, 11:09 PM   #18
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Default Re: Can you mix brass, steel, and aluminum pipe fittings?

Recently demo'd an old boiler system. Obviously lots of steel , but a large amount of brass fittings and valves were in direct contact with the steel. No signs of corrosion that would be considered heavy. However many of the joints did have sealant on them. The whole system had been abandoned about 20 years ago.
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Old 05-01-2010, 01:28 AM   #19
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Default Re: Can you mix brass, steel, and aluminum pipe fittings?

Quote:
Originally Posted by Skyline View Post
Are you sure brake line is large enough inside diameter for a tranny cooler?
If it's the same diameter as the steel lines already on the vehicle, then all is good.
It is probably 3/8" or 5/16"
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Old 05-01-2010, 07:06 PM   #20
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Default Re: Can you mix brass, steel, and aluminum pipe fittings?

like mentioned above, from the factory they mix them all together, id do it, and check on it in 6 months, if it looks good then youll probably be ok, if its starting to corrode to where iot could potentially break or leak replace it with all of the same metal because chances are it will do it again if you replace it with the same thing

that said, wheni built my last car, i used russels aluminum fuel line from the fuel cell to the carb, with steel hangers for the line under the car, and never had any corrosion after a year of driving, but the aluminum line was high quality stuff
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