Monel Fuel Tanks

[captnemo]

Looking at an old boat and it has 2 monel fuel tanks for a single diesel setup. What are the issues if any with monel tanks, would they have to be swapped for alum? or poly?

Thanks
Ric

[Captain Jay Kavanagh]

They are good, great infact way better than aluminum.

if they don't leak, they are probably ok.

Very very expensive to build.

[jawz12]

They are good, great infact way better than aluminum.

if they don't leak, they are probably ok.

Very very expensive to build.

not good,not good at all...
the monel will pin hole,it will also be effected by crevice corosion...aluminum,with an epoxy barrier coat is what you want-or fiberglass-strictly for diesel...
stay away from stainless steel and monel...

[Fritz]

not good,not good at all...
the monel will pin hole,it will also be effected by crevice corosion...aluminum,with an epoxy barrier coat is what you want-or fiberglass-strictly for diesel...
stay away from stainless steel and monel...

I disagree. The Leprechaun had three monel tanks that are 45 years old. Only one tank was bad having some soldered seam corrosion and that was the tank under the deck. I don't of any aluminum tank that will get that kind of life. Monel is a far superior corrosion resistant material to aluminum. A simple Google search will prove that. I do agree that fiberglass is best.

[jawz12]

I disagree. The Leprechaun had three monel tanks that are 45 years old. Only one tank was bad having some soldered seam corrosion and that was the tank under the deck. I don't of any aluminum tank that will get that kind of life. Monel is a far superior corrosion resistant material to aluminum. A simple Google search will prove that. I do agree that fiberglass is best.

it would appear that monel,and stainless steel would be a better choice,but,it will prove to be the opposite...

as far as the longevitey of aluminum fuel tanks,if the tanks are coated with a water proof epoxy barrier-the tanks were properly prepped,as in chemically etch primed,and the epoxy coating was applied to the correct thickness,approx as thick as a match book cover,the tanks will last indefinatley-it would be impossible for them to corrode,due to the fact the aluminum is seperated from any moisture...

[Fritz]

it would appear that monel,and stainless steel would be a better choice,but,it will prove to be the opposite...

as far as the longevitey of aluminum fuel tanks,if the tanks are coated with a water proof epoxy barrier-the tanks were properly prepped,as in chemically etch primed,and the epoxy coating was applied to the correct thickness,approx as thick as a match book cover,the tanks will last indefinatley-it would be impossible for them to corrode,due to the fact the aluminum is seperated from any moisture...

Impossible to corrode? That assumes that no moisture ever enters the tank and galvanism has not occured due to poor bonding. I don't have to tell you about moisture in boat fuel tanks.

I still say monel is far superior to aluminum. If its good enough for the US Navy, its good enough for me. I am not the only classic boat owner to have monel tanks still in service after 40 years. There are many others. As far as moisture is concerned, every so often I come across a monel water heater that is still in service after 40 years. The problem with monel is seam failure from corrosion and not corrosion in the metal itself.

Tell me how many aluminum tanks will still be in service after 40 years. I know-None. I have; however, replaced alumiunum tanks in two separate boats that were approximately 20 years old.

The reason why monel is no longer prevelent is the cost. A sheet of monel can easily be 5 times as expensive as stainless steel to say nothing of the comparison to the cost of aluminum.

So in answer to the gentlemen looking at a boat with monel tanks, I have talked to experts that tell me the tanks can outlive the boat and you. I would, however, carefully inspect all the tank seams for signs of corrosion and leaking.

BTW- Monel makes a superior shafting material as well.

[jawz12]

Impossible to corrode? That assumes that no moisture ever enters the tank and galvanism has not occured due to poor bonding. I don't have to tell you about moisture in boat fuel tanks.

I still say monel is far superior to aluminum. If its good enough for the US Navy, its good enough for me. I am not the only classic boat owner to have monel tanks still in service after 40 years. There are many others. As far as moisture is concerned, every so often I come across a monel water heater that is still in service after 40 years. The problem with monel is seam failure from corrosion and not corrosion in the metal itself.

Tell me how many aluminum tanks will still be in service after 40 years. I know-None. I have; however, replaced alumiunum tanks in two separate boats that were approximately 20 years old.

The reason why monel is no longer prevelent is the cost. A sheet of monel can easily be 5 times as expensive as stainless steel to say nothing of the comparison to the cost of aluminum.

So in answer to the gentlemen looking at a boat with monel tanks, I have talked to experts that tell me the tanks can outlive the boat and you. I would, however, carefully inspect all the tank seams for signs of corrosion and leaking.

BTW- Monel makes a superior shafting material as well.

here's an interesting article,it's about a boat made from monel...

http://query.nytimes.com/gst/abstrac...6E9C946496D6CF

allow me to continue...

i've never seen a fuel tank corrode from the inside,not saying it can't happen,but,i've yet to see it...
galvanism ?? ok,we have galvanic reactions,and then we have stray current electrolysis-take your pick ??

monel is subject to stress fractures="stress corrosion cracking"

it's also subject to pitting when it's against seawater for-think about that monel tank-holding 500g of diesel fuel,with sea water trapped between it...

we're all welcomed to our own oppinions,me,personally,if i see a boat with either a stainless steel or monel fuel tank,i get scared...

and for shafts,aquamet 22 is my choice...

[Fritz]

here's an interesting article,it's about a boat made from monel...

http://query.nytimes.com/gst/abstrac...6E9C946496D6CF

allow me to continue...

i've never seen a fuel tank corrode from the inside,not saying it can't happen,but,i've yet to see it...
galvanism ?? ok,we have galvanic reactions,and then we have stray current electrolysis-take your pick ??

monel is subject to stress fractures="stress corrosion cracking"

it's also subject to pitting when it's against seawater for-think about that monel tank-holding 500g of diesel fuel,with sea water trapped between it...

we're all welcomed to our own oppinions,me,personally,if i see a boat with either a stainless steel or monel fuel tank,i get scared...

and for shafts,aquamet 22 is my choice...

You really should do some more research. I think it would open your mind a little. I can't say anymore than in my humble opinion you are dead wrong in this case. And yes, tanks do corrode from the inside out. Let's just say we agree to disagree. Maybe you should check with a metalurgist or naval architect though. BTW- The New York Times is not exactly the most reliable source of info these days. As I said, I will stick with the US Navy. As for Aquamet 22, its substandard compared to monel particuarly with regard to corrosion.

[jawz12]

You really should do some more research. I think it would open your mind a little. I can't say anymore than in my humble opinion you are dead wrong in this case. And yes, tanks do corrode from the inside out. Let's just say we agree to disagree. Maybe you should check with a metalurgist or naval architect though. BTW- The New York Times is not exactly the most reliable source of info these days. As I said, I will stick with the US Navy. As for Aquamet 22, its substandard compared to monel particuarly with regard to corrosion.

i need to do research ?? i have a very open mind,for the record...
my "research " comes from being in this buisness for 20yrs...gotta know something by that time,huh ??
and again,in 20yrs,i've yet to see a tank corrode from the inside out...i didn't state it can't happen,again, i stated,i've never seen it happen...
the ny times,it was an article about a yacht built from monel...i remembered seeing this a while ago,this brought it to my attention again...
again,i do this stuff every day,i can tell you what works and what seems like a good idea on paper...
again,the properties i typed concerning monel,if you look into what i typed,you find it's right on the money...

as for shafting,i still prefer and use aquamet 22,same with most high end boat builders-guess we're all wrong huh ???

thanks for sharing your wisdom with me...

[Milkshake]

According to Boat Mechanical Systems Handbook By Dave Gerr.
Chapter 20, Page 315. Simply stated Monel is the best when comes to metal. Some more info on Monel by Wesley Fowler ( Marine Metal Corrison)
Monel is probably the best metal that can be chosen for use in the marine industry. This alloy ranks fairly high on the Galvanic Scale and is comprised of two-thirds nickel and one-third copper. It possesses high tensile strength (slightly less than 300 series stainless steels), is very ductile, and it is highly resistant to corrosion from atmospheric and sea water exposure. One of monel's best qualities is that it is most corrosion resistant in moving sea water. There are a variety of parts that are comprised of monel for marine use such as annular-threaded nails, screws, nuts,bolts, props, prop shafts, even wire rope. Monel can pit if it is exposed to long-term stagnant salt water, but very, very rarely.One indication that monel is beginning to corrode is when a grayish-green patina forms on the metal's surface. However, as stated before, it is a rare occasion to see corrosion develop on monel.
Hope this helps.