Glenn is correct, there are many people that make fuel and even water tanks
in Alu, but we all have predjudices and personnel favorites. Personnally, I
make diesel tanks in mild steel, Water tanks in 316TI. Yes, in Europe 316TI
is the same price as 316L. The major use in Europe of TI is not high
temperature applications, it is food processing vats, because it resists
acids better than L . I believe that most high temperature applications use
inconel, not 316. But be that as it may, this thread has exposed all the
available solutions and pitfalls for the audiance and that is what this NG
is all about.
Steve

"Glenn Ashmore" wrote in message
news:tVCwc.23786$My6.15959@fed1read05...
The "latest thinking" can get you in trouble more often than the tried
and true. As Evan, who has worked for some major marine architects,
said, recreational and small commercial boats almost always use aluminum
or black iron. Properly installed they will last the life of the boat.

I would not go to your local welding shop but custom tank makers like
Ezell in Florida, Aftermarket in Louisiana and Luther's Welding in Rhode
Island make hundreds of aluminum tanks a year to higher than USCG specs.
They have been building tanks for a long time and know what they are
doing.

316TI is more commonly available in Europe but considered a specialty
steel in the US. (read EXPENSIVE) The only difference between 316L and
316TI is that the TI limits carbon displacement at high temperatures.
That maintains the corrosion resistance better in the welds but does not
prevent stress cracking. 316TI is specified for applications where the
temperatures regularly exceeds 800F. If your tank ever gets that hot
you have a lot more to worry about than stress cracking.

A 500 gallon tank is WAY to big to be built in welded or even rotomolded
poly. Once you get larger than about 70 gallons they are almost always
cylindrical. Above about 250 gallons they are vertical cylinders like
farm storage tanks.

Wayne.B wrote:

There are a lot of different views and issues out there and I'd like
to get a sampling of that before making a decision. Most tank makers
will just go with what they know, not necessarily the latest thinking
or best approach. This is a big decision which will impact the future
relibility and resale value of the boat, and also involves major $$$s.


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com