Glenn Ashmore wrote:
I am beginning to wonder if locally built aluminum tanks are a good
idea. Every shop around here is tooled up for 6061 but marine tanks
need to be 5000 series. I will have to supply my own 5086 and TIG
welding rod and the best price I can find is in New Orleans. $130 a
4x10 sheet plus about $100 shipping. Still, a lot better than $300 a
sheet in Atlanta but not as good as $65/sheet for 1018 mild steel locally.

If I go with aluminum I think I will have to machine my own fittings.
There are very few sources of 5000 series aluminum fittings and the
selection is limited. It will be fairly simple to mill and tap some
NPTF fittings from 1" round for welding onto the tank.

I would like to hear some discussion of mild steel vs aluminum. Total
cost of mild steel tanks is about half that of aluminum but weighs about
twice as much. In this case a pair of custom 40 gallon would cost $600
in aluminum with some effort on my part to get the alloy vs $320 for
mild steel and weigh 72 pounds vs 125 for steel. From what I hear, a
well painted and installed steel tank will last just as long as
aluminum. Longer if the aluminum is not properly installed.

Ron White wrote:

I had my aluminum gasoline tanks built by Ezell Industries one of the
three
marine tank builders in Perry Fl. I let them decide where the baffles
were
( a wise move) also they provided the tank fitting and valves which
some of
need to be al. rather than ss or brass. One thing to consider also is the
pickup tubes, they made these with nylon? tubing swaged onto the al
tank top
fittings. Some other people I talked to were not up to speed on the
issue of
not using metal pickup tubes as they are subject to vibration and
fatigue.
Wouldn't want the pickup to break!!! I was very happy with Ezell and the
good work they did.
Then Painting, which I did. This system is my standard and I use it on
any
alum. thing I make for boats.
1, clean with acid ectching solution ( like, Ditzler DX533)
2 prime with dupont Variprime 615S self etching primer.
3 finish with several coats of 2 part epoxy primer.
For exposed alum. things, add about three finish coats of a urethane
enhanced enamel like Limco 1234.
All of the products are availble from automotive distributers I think the
key is using the variprime as is bonds to aluminum like nothing else I
know
of..



Either aluminum or steel will probably outlast both you and me. I've
seen diesel tanks for equipment on trucks made from steel that have
never been painted that were over 30 years old. I'm thinking about
making mine out of steel, but I plan on some type of coating inside and
out, just not sure what brand yet. Weight is no problem for me with a
steel boat and no plans for racing, just cruising. I would think that
would be a major deciding factor for you. Can you stand the weight.
Cost is always a major deciding factor for me. I have to build on the
cheap. I would think you would have more resources available. Is $300
or $400 a deciding factor? What about a poly tank? I'm sure you've
priced those, about the same as aluminum, but they're ready built.

Good Luck,

Donald

--
I'm building a Steel Robert's 434. You can sneak a peek if you wish by
clicking on me link below.
http://bellsouthpwp.net/d/o/donrayp/
'USA, Home of the best
politicians money can buy'

Donald Phillips wrote:

Either aluminum or steel will probably outlast both you and me. I've
seen diesel tanks for equipment on trucks made from steel that have
never been painted that were over 30 years old. I'm thinking about
making mine out of steel, but I plan on some type of coating inside and
out, just not sure what brand yet. Weight is no problem for me with a
steel boat and no plans for racing, just cruising. I would think that
would be a major deciding factor for you. Can you stand the weight.
Cost is always a major deciding factor for me. I have to build on the
cheap. I would think you would have more resources available. Is $300
or $400 a deciding factor? What about a poly tank? I'm sure you've
priced those, about the same as aluminum, but they're ready built.

I don't think interior coatings on diesel tanks are a good idea. Diesel
is not going to attack the metal and is a pretty good corrosion
preventive. Any coating carries the possibility of flaking off and
finding its way into the filters.

$300 would not be a deciding factor but now that I am on the down hill
side of the project I find Everett Dirksen's comment about "A billion
here, a billion there, pretty soon we are talking real money."
particularly relevent. :-)

I checked every maker of poly tanks but could not find a shape that
would work without wasting a lot of space or leaving the COG of the fuel
way to high and getting molds made for custom tanks is way to expensive.

I considered building my own out of glass/epoxy but I don't like the
risk. I built two water tanks and found it took a lot of effort to get
really solid laminations in the corners. If there is even one pin hole
there will be some weeping. I can live with a little fresh water
weeping but not diesel.

--
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

Did you check Ronco for a tank? They make more stock shapes than anyone I
know, and are very easy to work with. http://www.ronco-plastics.com/.

I'd stick with regular steel for the tanks if you can't find one at Ronco. I
have a pair that are 17 yrs. old and fine. You are right about the inside,
the diesel is a good anticorrosion treatment, as long as you keep the water
out. The outside should be painted with a good coating of some kind, and the
bottom should be supported so that air can circulate under it. Obviously,
you've got to keep the water off the top of the tank as well. Be sure to
have the maker put a sump with a dip tube from the top in the tank so you
can suck out any water that might end up in there.

"Glenn Ashmore" wrote in message
news:EoRjb.78877$sp2.14422@lakeread04...

Donald Phillips wrote:

Either aluminum or steel will probably outlast both you and me. I've
seen diesel tanks for equipment on trucks made from steel that have
never been painted that were over 30 years old. I'm thinking about
making mine out of steel, but I plan on some type of coating inside and
out, just not sure what brand yet. Weight is no problem for me with a
steel boat and no plans for racing, just cruising. I would think that
would be a major deciding factor for you. Can you stand the weight.
Cost is always a major deciding factor for me. I have to build on the
cheap. I would think you would have more resources available. Is $300
or $400 a deciding factor? What about a poly tank? I'm sure you've
priced those, about the same as aluminum, but they're ready built.

I don't think interior coatings on diesel tanks are a good idea. Diesel
is not going to attack the metal and is a pretty good corrosion
preventive. Any coating carries the possibility of flaking off and
finding its way into the filters.

$300 would not be a deciding factor but now that I am on the down hill
side of the project I find Everett Dirksen's comment about "A billion
here, a billion there, pretty soon we are talking real money."
particularly relevent. :-)

I checked every maker of poly tanks but could not find a shape that
would work without wasting a lot of space or leaving the COG of the fuel
way to high and getting molds made for custom tanks is way to expensive.

I considered building my own out of glass/epoxy but I don't like the
risk. I built two water tanks and found it took a lot of effort to get
really solid laminations in the corners. If there is even one pin hole
there will be some weeping. I can live with a little fresh water
weeping but not diesel.

--
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

Glenn,

FWIW: The Diesel tanks on Viking Star are 42 years old 1/4 steel and
are just fine. I scrapped down surface rust and repainted them this
last Spring, so I was all over them :-)

So, Steel does work well, as long as you keep water off of them.

( A dock mate with a 15-20year old CHB is looking to replace his
tanks. Engine room vents are set up to allow sea water ready access
to the top of the tanks.....)

One thing that I attribute to the good shape of my tanks is the fuel
pickup is at the bottom of the tanks, and the tanks are kind of wedge
shaped... At least in my mind, this has prevented standing water
from sitting in the bottoms of the tanks.

I have seen people talk about putting in a small 'well' or sump in
the bottom of tanks, and have the dip tube go into that well. That
way, and water in the tank will make its way into the well and at
least most of it will be drawn out.

-al-



On Thu, 16 Oct 2003 20:56:19 -0400, Glenn Ashmore
wrote:

I am beginning to wonder if locally built aluminum tanks are a good
idea. Every shop around here is tooled up for 6061 but marine tanks
need to be 5000 series. I will have to supply my own 5086 and TIG
welding rod and the best price I can find is in New Orleans. $130 a
4x10 sheet plus about $100 shipping. Still, a lot better than $300 a
sheet in Atlanta but not as good as $65/sheet for 1018 mild steel locally.

If I go with aluminum I think I will have to machine my own fittings.
There are very few sources of 5000 series aluminum fittings and the
selection is limited. It will be fairly simple to mill and tap some
NPTF fittings from 1" round for welding onto the tank.

I would like to hear some discussion of mild steel vs aluminum. Total
cost of mild steel tanks is about half that of aluminum but weighs about
twice as much. In this case a pair of custom 40 gallon would cost $600
in aluminum with some effort on my part to get the alloy vs $320 for
mild steel and weigh 72 pounds vs 125 for steel. From what I hear, a
well painted and installed steel tank will last just as long as
aluminum. Longer if the aluminum is not properly installed.

Guys, Dave Gerr (Elements of Boat Strength, pg.186) and others have
written volumes about 5000 vs. 6000 series aluminum alloys. They all
recommend 5000 series for marine applications, but caution that it's NOT
taboo to substitute 6000 series for use other than hull plate--including
non-intregal fuel tanks.
Welded aluminum sounds horribly weak from the drift of this discussion.
I guess that's why aluminum tankers supply the fuel to our local gas
stations? Think about it. That tanker you passed on the freeway this
morning held 5000 gallons of gasoline enclosed inside an aluminum
skin--0.180" sides/top and 0.220" belly--and it bridged 30' kingpin to
center of axles. The girth weld, 15' from the nearest bearing support is
a simple butt joint and was probably hand mig welded by a kid who didn't
finish high school.
Forget the semi trailer, the 50 gallon round or rectangular saddle tanks
hung off brackets bolted outboard from the truck chassis were most
likely welded aluminum and at 0.161" to 0.250" plate thickness--thicker
than they need to be--for added protection against puncture. And they
are hung--suspended by fabricated straps and/or U-brackets.
So please don't malign welded aluminum tanks. They've been the fuel tank
of choice for 50 years where light weight, low maintenance and cost
effectiveness are appreciated.
Regards,
Boat Dreams

boatdreams lifted the trapdoor, peered around and
wrote:

So please don't malign welded aluminum tanks. They've been the fuel tank
of choice for 50 years where light weight, low maintenance and cost
effectiveness are appreciated.

http://www.tek-tanks.com/

Would probably be my choice.

steveb wrote:

http://www.tek-tanks.com/

Would probably be my choice.

Tek-Tank will make welded HDPE water and holding tanks but their line of
fuel tanks is very limited. Fuel tanks have to be cross linked
polyethylene and you can't weld XLPE. It has to be rotomolded so you
are stuck with the tooling cost.

--
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

Glenn Ashmore wrote in message news:Gytkb.80009$sp2.24474@lakeread04...
steveb wrote:

http://www.tek-tanks.com/

Would probably be my choice.

Tek-Tank will make welded HDPE water and holding tanks but their line of
fuel tanks is very limited. Fuel tanks have to be cross linked
polyethylene and you can't weld XLPE. It has to be rotomolded so you
are stuck with the tooling cost.

I know this will not solve your problem, but on the twenty footer I
will be building, I planned areas such as fuel storage areas to use
common size readily available marine fuel tanks. Easily replaceable in
any marine store.
I don't need to carry as much as you, but I have two 6 gallon tanks
(mains) in the rear of the boat, with a third stored in the bow. I can
just plug them in as I need them. Just thought I would note that to
anyone else is in my situation and watching this thread.
Scotty

boatdreams wrote:
Guys, Dave Gerr (Elements of Boat Strength, pg.186) and others have
written volumes about 5000 vs. 6000 series aluminum alloys. They all
recommend 5000 series for marine applications, but caution that it's NOT
taboo to substitute 6000 series for use other than hull plate--including
non-intregal fuel tanks.

6000 series can be used but with limitations. First it does not weld
anything like as well as 5052 or 5086 and second it is much more
susceptible to corrosion than the 5000 series.

Welded aluminum sounds horribly weak from the drift of this discussion.

Nobody has said welded aluminum is "horribly weak" but it will loose
about 20% of its strength in the area of the weld which has to be taken
into consideration when designing the structure.

I guess that's why aluminum tankers supply the fuel to our local gas
stations? Think about it. That tanker you passed on the freeway this
morning held 5000 gallons of gasoline enclosed inside an aluminum
skin--0.180" sides/top and 0.220" belly--and it bridged 30' kingpin to
center of axles. The girth weld, 15' from the nearest bearing support is
a simple butt joint and was probably hand mig welded by a kid who didn't
finish high school.

Only about 20% of those shiny tankers are aluminum. Most are stainless.
Aluminum tankers must meet DOT406-AL standards. They have a
longitudinal structure, either chassis rails and cross members or
internal webbing to prevent excess flexing of the tank. They are also
built with 5000 series material. The design is fairly standardized and
carefully refined and that kid that welded it has 2 or 3 years of
training, uses a $5K TIG welder and lays the same bead 8 hours a day 5
days a week. The guy I am working with can hardly write his name but he
lays a beautiful full penetration bead. :-)

Forget the semi trailer, the 50 gallon round or rectangular saddle tanks
hung off brackets bolted outboard from the truck chassis were most
likely welded aluminum and at 0.161" to 0.250" plate thickness--thicker
than they need to be--for added protection against puncture. And they
are hung--suspended by fabricated straps and/or U-brackets.
So please don't malign welded aluminum tanks. They've been the fuel tank
of choice for 50 years where light weight, low maintenance and cost
effectiveness are appreciated.

It is very hard to compare automotive tanks to marine tanks. While
automotive tanks have to deal with vibration they don't get the constant
cyclical loading of marine tanks. They also don't have to contend with
a constant exposure to a highly corrosive environment.

Again, nothing wrong with aluminum tanks but they are not the ideal tank
for all situations. They do weigh between 20% and 50% less than mild
steel but they are more than twice as expensive. They are also more
susceptible to stress cracking than mild steel. Removing weight from
consideration I would rank the material for diesel tanks under about 40
gallons like this:
#1 Mild steel
#2 5086 aluminum
#3 5052 aluminum
#4 Cross linked polyethylene (XLPE)
#5 stainless steel (either 304 or 316)
#6 FRP.

Over 40 gallons XLPE drops to fifth place because of the difficulty in
adding baffles and the limited selection of stock shapes.

Now, before Lew gets to upset, ;-) because fiberglass can be molded on
site to the required space it is the most efficient for the use of
volume but it is almost impossible to keep diesel from permeating site
fabricated FRP. (duck'n and run'n) :-)

--
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

Sorry if this is off topic.
A few NOTs from someone with 15 years hands-on experience building
welded tanks--aluminum, steel and stainless:

First it {6061) does not weld anything like as well as 5052 or 5086

NOT. Welders don't even notice when they're moving from 5000 to 6000
unless one or the other is extrusion instead of plate. They're apt to
wire brush the extrusion a little more whichever alloy it is. They
don't change gas or rod/wire and don't even adjust their current if the
thickness and position are similar.

second it is much more susceptible to corrosion than the 5000 series.

NOT. 5083 and 5054 create a slight electrical potential and with 6061
you have slightly more. Don't use it in direct contact with salt water.
Bill Gates could afford to specify 5083 throughout a boat, but even he
could not guarantee that every piece of alloy on his boat is exactly
what he specified and probably paid for.

Only about 20% of those shiny tankers are aluminum. Most are
stainless.

NOT. ALL the shiny tankers you see dropping off fuel at the gas station
are aluminum.

They have a longitudinal structure, either chassis rails and cross
members or internal webbing to prevent excess flexing of the tank.

NOT. Truck tanks like semis and pull trailers are supported front and
back on bearing pads or short subframes. There is no longitudinal
stiffening other than the shell, rings, baffles and bulkheads that form
a structural tube. By excess flexing, you probably mean 'failure'. Any
aluminum semi tanker driver will tell you his 5000 gallon balloon flexes
with a period equal to the period of his suspension...And the first 50
years he drove the damn thing it scared the hell out of him.

The design is fairly standardized and carefully refined

NOT. There are off-the-shelf tanks and off-the-shelf boats. Every time
the customer buys a new tanker he recalculates the proportions of
regular, midrange and premium or diesel--always moving the baffles,
bulkheads and piping and often demaning a custom tube shape. Kind of
sounds like boaters. Everyone wants a 40' boat, but there are a lot of
interpretations of what goes in a 40' boat.

kand that kid that welded it has 2 or 3 years of training,

NOT. He completed a 60-day welding course at the county ROP training
site and the rest of his training was on-the-job training working with a
lead welder, definitely doing his share of weld-offs on the girth seams
of the semi-tankers we're talking about.

uses a $5K TIG welder and lays the same bead 8 hours a day 5
days a week.

NOT. All welded aluminum production tankers are mig welded. Period.
And nobody in a tank fabrication shop welds off every day. Your
aluminum hull might be a 90-day building project followed by 5 days of
weldoff. Tanker fabrication has a similar ratio of building : welding.

The guy I am working with can hardly write his name but he
lays a beautiful full penetration bead. :-)

NOT. One pass full penetration in butt welds is a myth. Your guy does
it the same way everybody else does. 1st he tacks it all together. 2nd
he runs a solid weld around the inside of the seam. 3rd he runs a
portable skill saw around the outside of the seam to remove
contamination and increase penetration. 4th the welds off the outside.

It is very hard to compare automotive tanks to marine tanks. While
automotive tanks have to deal with vibration they don't get the constant
cyclical loading of marine tanks. They also don't have to contend with
a constant exposure to a highly corrosive environment.

NOT. The Principle of Uniformitarianism assures us that the
mathematics, physics and chemistry on the 3rd rock from the Sun is the
same as on the 3rd rock from Polaris or anywhere else. Granted, the
period of waves is going to be different from the period of any given
set of trailer springs. The bending moments will differ. The number
and placement of anodes will differ. But we're talking about different
numbers, not different sciences.

Cheers,
Boat Dreams