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View Full Version : Aluminium Gas Tank, Brass Fittings - Any issues?



frclarke
10-11-2006, 02:56 PM
I just replaced my old gas tank with an aluminium one as suggested by many threads on the site. It's not easy to get aluminium fittings. Is brass going to cause galvanic problems?

FlynLow
10-11-2006, 04:01 PM
I've used brass without issues. Going Aum. you'd probably have go A/N which is very costly but nice. Are you plumbing tank to carb.?

BillG
10-11-2006, 05:12 PM
I would not use brass fittings in an aluminum tank. Use stainless or aluminum in the tank.
BillG

FlynLow
10-11-2006, 07:17 PM
frclarke, are you talking IN the tank or FROM the tank? In, I'd advise going alum., From, I haven't seen any troubles with Brass. No galvanized!

MOP
10-11-2006, 08:11 PM
Surprised the tank maker did not supply the proper fitting, if you can not find one local I would call Maybe RDS give them a card number and let them ship you one. Brass and aluminum make a bad combo!

Rootsy
10-11-2006, 08:32 PM
stainless fittings or rubber contacting the aluminum tank...

frclarke
10-12-2006, 12:15 PM
Thanks for the opinions. I think I'll take the conservative route and source aluminium fittings. The hardest item will be the fuel supply fitting with it's dip tube. The rest - I'll probably end up with aluminium AN fittings.

for flynlow - I'm converting from carb to a Holley Marine Projection 2D. The engine is a H&M 302.

Should be fun!

gcarter
10-12-2006, 12:32 PM
Surprised the tank maker did not supply the proper fitting, if you can not find one local I would call Maybe RDS give them a card number and let them ship you one. Brass and aluminum make a bad combo!
My RDS tank came w/a 90* SST pickup screwed into a half coupling welded into the top of the tank. It wouldn't tighten at the proper orientation for my hose. I ended up buying another pickup, trimmed it to length, and purchased a brass ball valve w/AN male fitting on the outboard side. I know this isn't the best combination (aluminum/SST/brass), but I used teflon tape on all the pipe threads. I inspect these joints frequently, and so far there are no issues.

FlynLow
10-12-2006, 06:03 PM
As long as your tank p/u is threaded your local welder should be able to hook you up with dip tube, mine did. I then mounted the water sep. and elec. fuel pump to the stringer in the "ski locker" between seats. From Pump to Carb I went AN. To plumb from tank to water sep. and pump I used brass and rubber hose as I couldn't get the SS hose to bend right. As gcarter stated I used teflon on the fittings and as I stated before there are no issues. Good Luck on your project!:)

DonziDave
10-12-2006, 08:26 PM
As a general rule, the farther apart two metals are on the periodic table, the more reactive they are with each other. Aluminum is (13) on the chart. Brass is a copper (29) and nickel (28) alloy. Iron is (26) and therefore more compatible than brass. But of course you don't want to use steel unless it is stainless. Having said this....go with aluminum fittings. :)

Here is a good science link that has tons of information on metals compatibility, marine corrosion, etc, etc.

http://www.martindalecenter.com/

Dave

joseph m. hahnl
10-15-2006, 07:29 PM
Brass is a copper (29) and nickel (28) alloy.)


Man Made Brass is Copper and Zinc . Not Nickel. Stainless steel contains Little or no Iron at all .Hence the name stainless. Stainless is extremly hostile to aluminum did you ever notice how stainless bolts never come out of Aluminum"usually there is a chalky build up that binds the thread".
Brass is way more Passive. You want the fitting to corode not the tank.
A brass Fitting should act as an anode and protect the tank from electrolysis.




joe

joseph m. hahnl
10-15-2006, 08:35 PM
I just replaced my old gas tank with an aluminium one as suggested by many threads on the site. It's not easy to get aluminium fittings. Is brass going to cause galvanic problems?


An aluminium tank exposed to salt water on the underside. WOW I wish I had suggested it. You got F'd at the get go. Salt strips the natural ability of aluminium to protect it self from corrosion. It keeps eating and eating .
even when salt is dry it absorbes water from the atmosphere eating and eating. Hopefully this is a lake boat and won't see the ocean.

If it were me while I had the cover off. I'd sell the tank to one of those nice folks that suggested using it. But I Know," your stuck with it Right"?

I hate to be so critical. But you really have to watch out ,who you take advise from. working in cause and effect is much safer than working in theory.
What is thought and what is physical? Theory can be disproven physics is fact ,Allways trust the facts.



joe

penbroke
10-15-2006, 08:56 PM
...you really have to watch out ,who you take advise from....

Ain't that the truth...


Frank :boggled:

MOP
10-15-2006, 09:19 PM
Yo You Got That Frank!:propeller

Having been trained by the military in aircraft sheet metal repair and maintainence and also being a marine tech for about as many years as some are old on this board I have to say some of the above is way off base!

Aluminum is very un happy in the presence of brass especialy in marine applications. When it comes to dis similar metals they are far apart on the scale. Many manufacturers supply S/S fitting with their tanks, true many supply aluminum. The caviate is aluminum can gawl threads where as S/S wil not, you are far better off using S/S for tank fittings! As an add on you would be amazed at how many millions of S/S rivits are holding titainium heat shields on the aircraft jet engines you fly in they terminate in aluminum! How that fact does not scare you from flying!

Sorry I just could not let this one go by!!!

joseph m. hahnl
10-16-2006, 06:02 PM
Yo You Got That Frank!:propeller



Aluminum is very un happy in the presence of brass especialy in marine applications. When it comes to dis similar metals they are far apart on the scale. Many manufacturers supply S/S fitting with their tanks, true many supply aluminum. The caviate is aluminum can gawl threads where as S/S wil not, you are far better off using S/S for tank fittings! As an add on you would be amazed at how many millions of S/S rivits are holding titainium heat shields on the aircraft jet engines you fly in they terminate in aluminum! How that fact does not scare you from flying!

Sorry I just could not let this one go by!!!






HA HA HA HA HA HA ! HA HA HA HA HA! YOU Crack me up.

Stand up at the improve:wink: . Maybe you should take 5 min and do some research:bonk: .Stainless is more noble on the galvonic scale than Brass.

The current difference between aluminum to all Brass is <.4V.
The current difference between 300 series stainless is <.7V.
Making it more hostile to aluminum as I said.
In either case the aluminum is the anodic metal.
Non carbon rubber or teflon is a good way to prevent metal to metal contact like George and Jammie said.
I think a small zinc anode that is easily accessable and removable would be a good Idea.


I, However did find out that cavity corrossion is actually slower in aluminum than stainless. Apparently if you passivate or use the proper coating the aluminum tank will out live a stainless tank and possibly last for ever "who would have thought" AH HAH
"thought not fact " You see what I mean.


I also discoverd that if you bond all of the metal components galvonic corrosion is dipersed over a greater area and is less galvonic destructive occurs.
It is also required By law that the fuel tank be bonded (bonding means grounding everthing to the engine or main ground).

It is also recomended that Anti seize be used on all stainless fasteners to prevent Gauling of the threads.


joe

Rootsy
10-16-2006, 08:22 PM
i seem to remember this thing in the 70's... where people were cheap-asses and decided to make ALUMINUM wire... and use it to power homes around the US... and a few years later they began catching on fire... because of the nifty REDOX reactions occuring between the aluminum wire and brass terminals... the aluminum oxidized caused an insulating barrier, raising the resistance of the connection and causing fire.... hmmmmm

if you REALLY want it broken down.. go speak to a chemist or do a google search... and you'll find more information than you can shake a stick at... personally... i have a stainless fitting in my aluminum tank... i have no issue with it...

btw, Stainless steel has Fe in it... its the high chromium content and other trace elements that makes it resistant to corrosion...

boxy
10-16-2006, 09:03 PM
The guys in Canada for petes sake.. Is there even saltwater up there??

Poodle, go left, right, or far enough up and you'll hit salt eventually. :D

If I had to guess though, I'm betting this particular Donzi gets to live in sparkling fresh Canadian spring water, the same kind that we ship by the truckload south to you guys everyday ..... :D :D

vonkamp
10-16-2006, 09:44 PM
Fiji is some good water but costs more than :beer: . So in the intrest of saving money and buying American.....It's Miller time.:yes: :yes:

joseph m. hahnl
10-17-2006, 03:42 PM
The guys in Canada for petes sake.. Is there even saltwater up there??
Joe, Stainless is NOT CG approved for fuel tanks last I checked.. As far as the rest of it, MILLIONS of boaters are proving you ll-informed on a daily basis.. MILLIONS...


Poodle. I was hasty and I admitted it ,I researched the issue and as I stated the aluminum tank will not Decay as fast as the stainless "I allready stated that". Stainless is not recomended for salt water fittings because of this fact. Using a untreated aluiminum tank is asking for trouble .If you do all the right things it will last for ever. What those things are I would have to do more research on the proper method of sealing the tank. Quite frankly that is exactly what I would do before I took any advise from any one.
As far as the brass Vrse aluminum well I didn't make up the laws of physics nature did. I mearly Follow them and when a Metalorgist Does testing and research on it and says to me that the brass is more passive because the voltage difference is higher in stainless I believe him. The problem with using the periodic table of elements is"The Number of protons nuetrons and electrons is Irelevent to the galvanic scale. for instance > Zinc is a bigger atom than aluminum yet it is an anode to aluminum and pretty much all metals.Galvanic corrosion is measured by how much voltage passes thru the metal the higher the voltage difference between the disimilar metals the more decay.I didn't make that up or pull that out of my hat. Scientist Tested it.It is true there are alot of essays written on the subject. But if you don't know how to read or don't bother to read the information well then it's ptretty much useless is'nt it.

I'm Kind of tired of going round and round with Beligerent people who think that because they did it, that makes it Word. As you all no I am a machinist and I work with metal every day. I have cut pretty much every substance on earth.
I use math and formulas Just like the engineers do. Yet they think they know something I don't .I Live in this modern world of modern engineering. Yes the one where the beligerent use materials that are illsuited for there application"maybe they smoked to much pot in college".It's become an age where most every thing either fails or doesn't work. It's not just the fact that it's made in China. It's the fact that basic fundamentals and methods are ignored. That is all I have to say on this matter,and pretty much on anything on this site" No big loss I'm sure"

Poodle, I thank you for all of your help in the past and out of all here, I have trusted your wisdom for it hasn't let me down .

So to all of you Safe boating and have a happy life.


joe

Rootsy
10-17-2006, 07:47 PM
Poodle. I was hasty and I admitted it ,I researched the issue and as I stated the aluminum tank will not Decay as fast as the stainless "I allready stated that". Stainless is not recomended for salt water fittings because of this fact. Using a untreated aluiminum tank is asking for trouble .If you do all the right things it will last for ever. What those things are I would have to do more research on the proper method of sealing the tank. Quite frankly that is exactly what I would do before I took any advise from any one.
As far as the brass Vrse aluminum well I didn't make up the laws of physics nature did. I mearly Follow them and when a Metalorgist Does testing and research on it and says to me that the brass is more passive because the voltage difference is higher in stainless I believe him. The problem with using the periodic table of elements is"The Number of protons nuetrons and electrons is Irelevent to the galvanic scale. for instance > Zinc is a bigger atom than aluminum yet it is an anode to aluminum and pretty much all metals.Galvanic corrosion is measured by how much voltage passes thru the metal the higher the voltage difference between the disimilar metals the more decay.I didn't make that up or pull that out of my hat. Scientist Tested it.It is true there are alot of essays written on the subject. But if you don't know how to read or don't bother to read the information well then it's ptretty much useless is'nt it.
I'm Kind of tired of going round and round with Beligerent people who think that because they did it, that makes it Word. As you all no I am a machinist and I work with metal every day. I have cut pretty much every substance on earth.
I use math and formulas Just like the engineers do. Yet they think they know something I don't .I Live in this modern world of modern engineering. Yes the one where the beligerent use materials that are illsuited for there application"maybe they smoked to much pot in college".It's become an age where most every thing either fails or doesn't work. It's not just the fact that it's made in China. It's the fact that basic fundamentals and methods are ignored. That is all I have to say on this matter,and pretty much on anything on this site" No big loss I'm sure"
Poodle, I thank you for all of your help in the past and out of all here, I have trusted your wisdom for it hasn't let me down .
So to all of you Safe boating and have a happy life.
joe

loading a part.. pushing the button on the pendant and holding up the table til the spindle stops isn't what i call machining :lookaroun

JR - onna them dere dum dezine injuneres.... :bonk:

Ricardo Grande
10-17-2006, 08:33 PM
Poodle. I was hasty and I admitted it ,I researched the issue and as I stated the aluminum tank will not Decay as fast as the stainless "I allready stated that". Stainless is not recomended for salt water fittings because of this fact. Using a untreated aluiminum tank is asking for trouble .If you do all the right things it will last for ever. What those things are I would have to do more research on the proper method of sealing the tank. Quite frankly that is exactly what I would do before I took any advise from any one.
As far as the brass Vrse aluminum well I didn't make up the laws of physics nature did. I mearly Follow them and when a Metalorgist Does testing and research on it and says to me that the brass is more passive because the voltage difference is higher in stainless I believe him. The problem with using the periodic table of elements is"The Number of protons nuetrons and electrons is Irelevent to the galvanic scale. for instance > Zinc is a bigger atom than aluminum yet it is an anode to aluminum and pretty much all metals.Galvanic corrosion is measured by how much voltage passes thru the metal the higher the voltage difference between the disimilar metals the more decay.I didn't make that up or pull that out of my hat. Scientist Tested it.It is true there are alot of essays written on the subject. But if you don't know how to read or don't bother to read the information well then it's ptretty much useless is'nt it.
I'm Kind of tired of going round and round with Beligerent people who think that because they did it, that makes it Word. As you all no I am a machinist and I work with metal every day. I have cut pretty much every substance on earth.
I use math and formulas Just like the engineers do. Yet they think they know something I don't .I Live in this modern world of modern engineering. Yes the one where the beligerent use materials that are illsuited for there application"maybe they smoked to much pot in college".It's become an age where most every thing either fails or doesn't work. It's not just the fact that it's made in China. It's the fact that basic fundamentals and methods are ignored. That is all I have to say on this matter,and pretty much on anything on this site" No big loss I'm sure"
Poodle, I thank you for all of your help in the past and out of all here, I have trusted your wisdom for it hasn't let me down .
So to all of you Safe boating and have a happy life.
joe


Actually, the word is "belligerent" you may want to look it up.

http://www.dictionary.com

BigGrizzly
10-18-2006, 10:07 AM
I remember like Rootsy but it was late 1960s Codes did allow it because the code malers ignored the periodic table and common sence. They did it on welders too. guess what right where you plug in the welding lead coroded amd burnt the wire plus alu. gets hotter faster and the flow of electrisity is restricted. Many welders broke down. I had one and was really pissed at it dropping an arc. needless to say it was a give a way unit. Fact is don't mix brass ande aluminum especially id DC power is addeded such as a fuel sending unit. Aluminum fittings are eas to com by, so id monell which is approved and no harm. steel also works. AS for stainless and alunimun better tell airquip not to combine the two. No one on this post was being nasty just having fun among friends.

DonziJon
10-18-2006, 10:41 AM
Funny how things sometimes get WAY TOO complicated. :confused: Somewhere many years ago I read that the "difference" in surface area between two dissimilar metals in intimate contact with each other had a direct bearing on the corrossion of the "less noble" metal.

As an example, suppose you have One square inch of Brass in intimate contact with One square inch of Aluminum in a salt water environment. Guess what: You have a problem. The Aluminum will dosolve in a short time.

Now, if you have One square inch of Brass in intimate contact with 100 square inches of Aluminum, you will have MUCH LESS of a problem. You may not even see ANY corrossion. :bonk:

I've owned sailboats in a salt water invironment for over 25 years. Sailboats have Aluminum masts with fittings attached made of various materials, and fastened to the Aluminum masts with Stainless fasteners. If you use a SS "uncoated" fastener in the Aluminum mast... eventually you may have a problem getting the fastener out. Powdery deposits, etc. etc.

The SOLUTION, which works every time it's tried, is to coat the fastener threads with "Silicone Seal" which insulates the SS from the Aluminum. Sailboats masts are usually "Anodized"...BUT the hole you just drilled for either tapping, or using Self Tapping screws is not. SO: A little dab'l do ya just fine.

For the gas line fitting that started this whole thing, George had an alternative, and probably neater solution. Teflon Tape, "Ribbon Dope", or plumbers tape, etc. A little "Permatex" gasket goop on the threads would also work, without the risk of dropping shreads of Teflon Tape or cured Silicone Seal INTO the tank if you ever have to remove the fitting.

Just some food for thought ..if you're hungry. :) John

ALLAN BROWN
10-18-2006, 11:21 AM
Wait a frickin' minute! We used aluminum (against the CG's wishes) in the 1963 Formulas. It was grade 3003, which has all the integrity of a soda cracker in salt water. They have learned a thing or two about metallurgy (metalorgy?) in the past 40 years or so. You can put 5086 alloy in salt water and without some outside influence, nothing will happen to it. Ever see the "Hero" tugboats in Fort Lauderdale? They are all aluminum, and not even painted, except for antifouling. A battery is two dissimilar metals in an acid. Gasoline is not an acid. Use anything you wish for a fitting. It won't make a dang bit of difference.................................

ALLAN BROWN
10-18-2006, 12:44 PM
Further to that guy with the big paragraph: Magnesium is an anode for aluminum, zinc is not...........................

BUIZILLA
10-18-2006, 01:06 PM
amen !!!

BigGrizzly
10-18-2006, 01:27 PM
As usual Brownie fixed that issue! I over looked the minor detail of gasoline. Its 80degrees up here and I am going for a boat ride.

David Hartmann
10-22-2006, 07:24 PM
So this got a little out of control but I did see a few posts back someone mentioning the use of Teflon Tape.

I did this 3 years ago. I got about 1/2 a season before I started to smell a little gasoline when taking the cover off the boat. IT was the tape on the fill fitting that was leaking. a year later I had to track down another leak. It turned out that I had to redo all of the fittings.

This is a very serious and extremely common mistake. Even very skilled people will make this mistake because Teflon Tape is the right way to handle so many applications. I would bet there are even a few mfg'ers that make this mistake sometimes.

I would advise everyone to look at all of their fittings and if you see teflon tape remove the fitting and reinstall with a proper gel or paste designed for gasoline fittings. Don't wait for a leak or worse. It is worth a check.

MOP
10-23-2006, 06:28 AM
The Teflon tape that is right for the job is Teflon Yellow it is made for fuel, the white will not stand up to most petro products.

David Hartmann
10-23-2006, 06:29 PM
The Teflon tape that is right for the job is Teflon Yellow it is made for fuel, the white will not stand up to most petro products.

Thanks, I went with a gel type sealer but the yellow teflon tape is good for fuel and it is cleaner to work with.