Proper Material for Water and Fuel Fittings

[twistedtree]

I need to add a few elbows, tees, and adapters to both my fuel tanks and water tanks, and want to confirm what material(s) are acceptable to use in each case. In both cases, my tanks are aluminum, adn the existing shutoff valves are Parker (red brass I think) for fuel, and Groco bronze for water. There also is an adapter right at the tank which appears to be aluminum or maybe stainless or some alloy. I don't know if it's there just to convert thread styles, or it it's there to address corrosion between dissimilar metals. And the new fitting I need to add is stainless.

So to summarize, what fitting material should be used to get from an aluminum tank to a stainless fitting? Since there is no salt water involved, does it even matter from a corrosion perspective, and should I just select components that are fuel rated and water rated respectively?

Thanks,

Peter

[peghall]

It's usually best to have as FEW tees, wyes, elbows and adapters in plumbing ("plumbing" expanded to include fuel lines) as possible. Why do you think you need to add more to either system?

Or are you attempting to prove it's true that normal people believe that if it ain't broke, don't fix it, but engineers believe that if it ain't broke, it doesn't have enough features yet.

[Cheechako]

You could use an alum fitting if you can find it.... not sure why you need a fitting between them.. adapting a size? Stainless and even brass are commonly used on the top of tanks... even though Brass and Alum is not a good mix. I would use stainless if you can get it. For water plastic would be fine.

[twistedtree]

Originally Posted by peghall

It's usually best to have as FEW tees, wyes, elbows and adapters in plumbing ("plumbing" expanded to include fuel lines) as possible. Why do you think you need to add more to either system?

Or are you attempting to prove it's true that normal people believe that if it ain't broke, don't fix it, but engineers believe that if it ain't broke, it doesn't have enough features yet.

You know, that's really not very helpful.

[twistedtree]

Originally Posted by Cheechako

You could use an alum fitting if you can find it.... not sure why you need a fitting between them.. adapting a size? Stainless and even brass are commonly used on the top of tanks... even though Brass and Alum is not a good mix. I would use stainless if you can get it. For water plastic would be fine.

Thanks. One of the reasons I ask is because the factory-supplied fittings have a stainless adapter between the tank and brass/bronze shutoffs in every location, and it's not clear to me why they did that. But it sure looks intentional.

[Cheechako]

Yeah, they were probably dont their best to keep the brass away from the Alum.

[twistedtree]

Originally Posted by Cheechako

Yeah, they were probably dont their best to keep the brass away from the Alum.

That would make sense, but stainless and aluminum are not happy together either, right? Or is that just in the presence of salt water? I take it stainless is still better than brass in contact with the aluminum?

For reference, here's the thread with background on why I'm asking about this http://www.cruisersforum.com/forums/...tml#post908756

But since it's a specific materials question, I felt it was better to have a separate thread.

[Cheechako]

I think SS is better than brass anyway:
"In a couple with chromium or stainless steel in atmospheric or other mild environments, the rate of aluminum galvanic corrosion is low.
In a couple with copper, however, the corrosion rate of aluminum is high."

[s/v Jedi]

I have aluminium diesel tanks and they had an aluminium plug in the bottom of the sump. I replaced the plug with a cast bronze elbow, using plenty hard setting Permatex #1 as thread sealant. I did that 7 years ago and today it looks like he day I put them on. The sealant will mostly isolate the materials.

ciao!
Nick.

[bobconnie]

Good Old Black Permatex ! works on most everthing !! water fuel even sea water if yall are carefull !! worked for me for many years !! always carry many tubes off no 1 and the Yellow Gorilla Snot or sometimes known as rubber window adhiseve ! best oil gasket glue ever !! just my 2 cents

[Me-and-Boo]

Originally Posted by bobconnie

Good Old Black Permatex ! works on most everthing !! water fuel even sea water if yall are carefull !! worked for me for many years !! always carry many tubes off no 1 and the Yellow Gorilla Snot or sometimes known as rubber window adhiseve ! best oil gasket glue ever !! just my 2 cents

A lesson I learned many years ago, and it holds still today, is when working with solvents (water is a solvent) read the adhesive's instructions very carefully. Some do not do well with gasoline, some do not do well with diesel. That could be very bad if you are sitting off shore and smell something very wrong.