Landracing Forum
Tech Information => Technical Discussion => Topic started by: tauruck on February 06, 2015, 12:11:38 AM
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I'd like thoughts/advice on a Stainless Steel gas tank.
Why do I want to build one?.
I have the material and access to equipment capable
of doing radius bends eliminating the need for
welding on the corners.
I can't weld Aluminum and don't want to use mild steel.
I have a lot of fuel tank foam I'd like to use and I'm not sure if
baffles would be a good idea.
The tank would be 1000 x 500 x 300mm.
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Let's see
Pros
Not concerned about the weight... check
Stainless will hold up better in the salt...check
Stainless will polish up nice and look great... check
Stainless is durable in the event of a mishap...check
I find stainless easier to tig than aluminum so for me...check
Access to sheet metal tools to do radius bends...check
Cons
A stainless is bear to drill and most fuel fillers will require 15 to 25 1/4" holes...
If you weld it you will need to back fill with argon...
For me stainless is good.
BR
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Mike, back purge will be absolutely mandatory. I don't know how you're set up to do it. I know some guys just put a "Y" on the outlet of the flow meter, that's what I used to do but it wastes argon and results in inaccurate flow to the weld. A while back I posted pictures of the set up I built so that back purge is only a turn of the tap away and it solves the aforementioned problems.
http://www.landracing.com/forum/index.php/topic,10731.0.html
I used two new identical flow meters because I had easy access to them but it isn't necessary to have identical units. They'll still each measure the flow accurately.
Hope this helps.
Pete
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x 3 on the back purge.
:cheers:
F/B
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Mike,
What gauge stainless you thinking about using? Back purge is certainly required you might also try this flux, http://www.solarflux.com/Pages/Productinfo.html, which also works very well. I have used it on headers before with good success.
My real question is: Why are you building a 40 gallon fuel tank? Copious amounts of nitro??
Rex
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Guys thank you.
My mate Willie gave me a sheet of 304.
Same stuff as I use on the headers.
My tig set up has "T" piece that I unblock for back purging.
Not too worried about wasting some gas.
My house is set up for 220v and all the good machines
for welding Aluminum use 380v but in saying that Guido
(my welding supplier) advised that unless I'm welding
Aluminum for a living, 8 hours a day it would be a waste.
My Ally welding attempts haven't been great and I could use
his equipment but I believe in leaving the important stuff to the pros.
I just clicked with the SS. It's the best material I've welded.
Vince Roman from Burns SS really helped me a lot and I have
faith in the finished product I've done.
I know the material is tough on drill bits etc but I'll handle it.
Rex, I come from a carburetor background and according to
my turbo experts I needed at least that size tank for the 16
2200cc Bosch injectors.
I'd rather err on the side of too big than not enough and the tank
will fit the space provided perfectly.
The advice I got locally is that Ethanol corrodes Aluminum over time
and my operation as under funded as it is needs to have everything
right.
You guys always put my mind at ease and every bit of advice I've
ever gotten has been 100% on the money.
Thanks Bill, Peter, Mark and Rex. :cheers: :cheers: :cheers: :cheers: :cheers:
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...My house is set up for 220v and all the good machines for welding Aluminum use 380v but in saying that Guido (my welding supplier) advised that unless I'm welding Aluminum for a living, 8 hours a day it would be a waste.....
There are a number of good 220v TIG welders here that will do about any job you are going to do on a race car. I have a Miller mig and a 225 amp square wave Lincoln TIG that I love and wish I would of gotten it or one like it years earlier than I did so I'll have to disagree on Guido's advice. If at some point you can get one do and you will say 'why didn't I do this before' like I did :-),
Sumner
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I hear you Sum and I would have loved a machine like that
but I do so little Ally stuff it would be wasted.
I have three welded parts on the liner so far and
Duncan did such a neat job. I'd never get to that
level. He charges me in beer so a six pack is well
worth it.
The crazy thing is that I buy all my welding equipment
from Guido and he gave me a roll of Aluminum wire for
my Mig machine.
I tried welding some flat plate and the welds were sort
of OK but not what I wanted. There was so much smoke
I decided to give the thing a miss.
A few weeks later we go to a client of his who has the same machine
as mine. Guido was setting up the system. He asks me to run a few beads
to show the guy. Perfect welds with no smoke, well very little.
I still can't figure out why I had white soot all over my helmet
when I did that test at my place. :evil:
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Test piece a different alloy?
Different pre weld cleaning procedures?
I'm not a welder, just a part time practicing wanabe looking to improve my abilities.
Ed
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I'm going to Guido to come over and we'll do a test.
The sample I did at his client made me look good. :-D
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Mike, you can cut holes in stainless with a hole saw. Machining the stuff is possible. It takes some time to get a feel for the material. My estimate is it takes two or three times longer to make a part from stainless as from mild steel. Some of the stainless alloys are easier to work with than others.
You will find, that taking advantage of stainless' superior strength, it is possible to use less of it than with aluminum. In some cases a part designed from stainless can be as light as one made from aluminum.
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The methanol tank (in front of passenger-side bank of pulling engine) is only .030" thick so it's very light, but quite rigid due to its shape. I cut the pattern shapes from 300-series stainless and had a professional shop expertly TIG it together. Still working well after many years.
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The trick is lots of tacks and a good back purge. Solar Flux type B painted on the back side of the material is an alternative to back purging.
Pete
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Back purging is so useful. Requires some time and thinking
but the result is exciting.
FREUD
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Thanks Pete.
Freud, long time no hear!!!.
I hope you're well and keeping warm. :cheers:
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On second thought, that really isn't a good application for Solar Flux. The glass like residue might break away and go where it shouldn't. :-( :-( :-(
I've been known to use the Solar Flux in exhaust systems where it works really well.
Pete
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Pete, your advice is always on the money.
Thank you for the update. I've never used flux
but am willing to learn and do what it takes.
When you work with composites all day the welding
is a welcome break. I love it and hope to get better
at it. The welding on the exhausts I did is fine according
to the guy that built the Dakar truck. How bad does the SS
warp?.
I never do a full pass anyway but when the tank is done
I don't want it looking like junk.
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"How bad does the SS warp?"
That's why you use lots of small tacks. Practice on some scrap before you start on the real thing.
Pete
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Here's an answer from a weldor (this is the correct spelling) and mechanical
engineer (with a concentration in welding/metallurgy) of many years.
Stainless steel distorts a LOT from welding. Here's why:
Shortly after it was discovered (by accident, after somebody melted some
chromium and mild steel together . . . the resulting alloy didn't rust very
much at all), it was learned that this material resisted heat pretty well.
In other words, it retained some impressively-high strength even while hot.
So the name "heat-resisting steel" was applied and generally used. But
in common applications such as cooking utensils and liquid containers, where
strength is not as important as chemical inertness, the word "stainless" became
a major marketing tool.
Back to the concept of "heat-resisting" . . . If you can imagine red-hot steel
having about two percent of the strength of steel at room temperature, then you
know that heating the steel makes it quite easy to bend. I think most or all of
us have done this. Stainless steel, by contrast, maintains much more of its
strength even while red-hot. This is why many industrial components are made
of it, for use in hot environments. Stainless steel at 1200 degrees F may have
somewhere around 20 percent of its room-temperature strength.
Now, consider a weld cooling and shrinking as it cools. A weld made of stainless
steel, as it cools (while still red-hot) will pull harder than a red-hot weld made
of mild (regular, common) steel. For this reason, stainless steel has a reputation
for "pulling like a m-f" when the weld cools. In some instances, one can compensate
for this by fixturing geometrically "biased" so that after the weldment is taken out
of the fixture, "springback" can pull the weldment into the desired configuration. An
example might be as follows: If you want to weld two flat plates together to form
an "L" shaped weldment, maybe they should be clamped so the angle between them
is about 92 degrees (obtuse) on the side where a fillet weld will be. When the weldment
cools, it will pull about 2 degrees, closing that 92-degree angle to about 90 degrees.
As mentioned in earlier posts, lots and lots of small tack welds will help. Welding both
sides of the material will also help, alternating from one side to the other (even in tack
welding). But this may not always be practical, as in the case of a small fuel tank. The
tank could be designed so that welding can be done on the inside and the outside of major
subweldments, before the final welding is done (on the outside only of the last seam) to
join the subweldments together, resulting in the final weldment.
For a fuel tank, here are my suggestions . . . 1. Use fairly thick stainless steel, since in
land speed racing, you don't need to be too concerned about weight -- at least compared
to aerodynamic drag and other friction. Also, use stainless filler material and add it while
welding (instead of simply melting the sheets together).* 2. If the walls will be flat and
distortion would be a big issue (usually for esthetics only, in my opinion), you could add
stiffener ribs on the inside or outside of the walls before the walls are welded together.*
I also agree strongly that "back-purging" with argon is a wonderful idea, instead of using
any kind of flux. Don't try to save money by using any other gas for this purging, as it
works best with argon. I can explain later why. There is a lot of experience available
from others. Please consult them. Even purging with argon can be done wrong, so
ask for details about argon flow rate, and "scavenging" during initial purging. And I also
strongly suggest using a gas lens on your GTAW (formerly called "TIG") welding torch.
*You could ask me for more (e-mailed) details if you want, on all of this.
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Thanks Tallguy, that was awesome. :cheers: :cheers: :cheers:
I really appreciate the explanation.
This tank project is going to test me.
I'll do some more thinking and planning before I dive in.
Mike.
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Mike;
Consider using a nickel silver braze weld for stainless steel. It has far less distortion than fusion welding since the stainless is not heated high enough to melt a weld puddle. It also does not need argon shielding, relying instead on a high temperature flux.
I like to use Harris #17FC rod with its corresponding flux. I paint both outside & inside surfaces with flux and then heat the stainless to a low red heat with a neutral oxy- acetylene torch. The rod melts on the surface of the stainless and by controlling the heat and direction of the torch, you can control where it flows. With a little less heat, it melts but doesn't flow much at all, allowing you to form a bead. The flux is removed by hot water (so they say) but a phosphoric acid solution helps.
The resulting joint (preferably a lap joint with close fit) has very high strength- about 80,000psi, and the distortion is quite low compared to fusion welding. This is NOT brazing like one normally associates with brass alloys.
Regards, Neil Tucson, AZ
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Mike;
Consider using a nickel silver braze weld for stainless steel. It has far less distortion than fusion welding since the stainless is not heated high enough to melt a weld puddle. It also does not need argon shielding, relying instead on a high temperature flux.
I like to use Harris #17FC rod with its corresponding flux. I paint both outside & inside surfaces with flux and then heat the stainless to a low red heat with a neutral oxy- acetylene torch. The rod melts on the surface of the stainless and by controlling the heat and direction of the torch, you can control where it flows. With a little less heat, it melts but doesn't flow much at all, allowing you to form a bead. The flux is removed by hot water (so they say) but a phosphoric acid solution helps.
The resulting joint (preferably a lap joint with close fit) has very high strength- about 80,000psi, and the distortion is quite low compared to fusion welding. This is NOT brazing like one normally associates with brass alloys.
Regards, Neil Tucson, AZ
LOTS of early British chassis were jig made steel tubing brazed together with nickel silver rod and a "bubbler" fluxer filled with the liquid flux.
ONLY the welder knows if the joint is properly made, but with a bit of practice good joints can be done. You do need to practice to prevent "cold shuts" which do not adhere well to the parent metal.
I've seen the mild steel/low carbon steel tubes tear before a properly made joint will fail. 80,000 psi is much higher strength than low carbon steels.
:cheers:
Fordboy
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Guys, I'm building a 1100mm wide bending break.
Nothing fancy and built from off cuts and general junk
that gathers.
It isn't done and I'm giving someone Mig lessons so the
neatness isn't tops.
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I bent some 2mm mild steel over the mandrel which is 1"
using pressure from the vice.
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I've got this new filler cap.
Never used but had it a while.
I'm thinking of using it but you guys might have
opinions I'd like to hear.
Going to use the bending break to shape some Stainless for the tank.
Looks like we're using 1,6mm?????.
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Looks good, Mike. I'd add a small ear under one of the bolts and drill a hole in it so that the cap could be safety wired closed. It is a tight cap but safety wire adds an extra layer of security.
Regards, Neil Tucson, AZ
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Thanks Neil. I do have a bunch of new blind anchor nuts with a yellow seal.
I know they are aviation spec. I'm thinking of using those instead of the stuff
supplied with the cap. I'll wire that sucker good for sure!!!.
The cap looks OK but has a cork seal????. It came on a plastic tank I bought
from Summit a long time ago. I changed it out in favour of a quick release cap
I found in an airplane junk yard. I don't trust that cap either due to its age,
condition.
I'll be running Ethanol and I'm not sure how the cork holds up.
What do you think?. :cheers:
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I wouldn't rely on cork, as it's made of a bunch of small (natural) chunks of bark stuck
together with who-knows-what.
There are lots of nice (rubber) materials available that can resist chemical effects
(dissolving, for example) of various chemicals such as alcohols. I'd use rubber. Gasket
companies can custom-fab for you if you want, as well as providing advice on a suitable
material.
Sometimes it's good to pay the experts for their experience/knowledge.
And by the way, please don't forget to provide for venting, to allow air to enter
the tank as fuel is consumed. You wouldn't want to buckle the tank or starve your
engine, I assume. And if you do go with the experts (gasket company), please be
aware that once the setup for fabbing one gasket is done, the subsequent (second,
third, etc.) gaskets are relatively inexpensive. I'd buy several, as spares, and keep
them stored in ziplok bags, away from sunlight -- which is harmful to some types of
plastic/rubber.
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Make sure the vent is adequately sized. I would add, it is advisable to use a tip over valve at the tank to minimize spillage/leakage if the vehicle flips over also use a filter on the vent line to limit contamination of the fuel tank (ie. dirt, salt , etc)
Regards
Don
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Tallguy and Don, thanks for offering advice.
I really appreciate your input. :cheers: :cheers: :cheers:
One of my sponsors is a rubber gasket manufacturer so I'll hand over the cork
and have them make a real gasket.
The cork was a concern and you also came to that conclusion.
The tip over valve will have to be something special. The filler is a big one
and I'll investigate and revert back.
The vent line is a done deal. I've been there before but all the input helps.
Thanks again.
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Mike, I suspect you already know a properly constructed vent will also serve as the tip-over valve.
Keep up the good work :cheers:
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I didn't know that but with you guys all
helping I'm learning. Thanks B. :cheers:
Now you've got me thinking....... I had
something like that here, there was a ball in a cage?.
I'll have a look.
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Here's a link to a guy who has built 2 stainless gas tanks < http://www.midlana.com/Diaries/Current/ (http://www.midlana.com/Diaries/Current/) > Under 1 Feb 2015 "....The sheet metal shop was unable to close the sheet, meaning three long weld seams. Fearing the extreme warping that happened with tank V1.0, it was welded in 1" increments, moving back and forth, side to side, and was rewarded with virtually no warping. Seen in the pictures below is the comparison of the tanks V1.0 and V2.0. Tank V1.0 warped, bending the top 4" section of 0.065" stainless on edge nearly 1.5" over 44". I can hardly imagine the enormous force needed to bend a 4" thick section of stainless! Tank V2.0 shows practically no warping at all - very happy about that. ....." Maybe there will be something you'll find useful.
Roy
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Roy, thank you.
Perfect. :cheers: :cheers:
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Here's the latest update on the tank.
I found a sponsor. With my project being an
underfunded roller coaster I try get help where I
can and if that fails I have to try do it myself.
I sent out 5 proposals and got two positives.
I told the guys that the tank was a complex piece
that need radiused corners and welding needed
back purging etc and if that was a problem they could
supply materials and I'd do it.
They never went for that and Latham Engineering Africa
is going to do the tank to spec.
The guys are high tech and know far more than I do.
Check them out.
http://www.lathamengineeringafrica.co.za/
Divine intervention again. :cheers: :cheers: :cheers:
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I am not much one for depending on ball check valves--- a vent line properly done has very, very little chance of fuel getting out; be sure and vent the front most corner so that under hard acceleration the fuel doesn't ride up and cover the vent.
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Will do. Thanks Sparky.
What size line?. -10?.
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Double up on the weld-in's Mate. You can plug them if you don't use them, a lot easier than trying to add more later when you go to that 600 incher.
Sid.
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Our vent uses a spring loaded ball as well as a rollover line design. When designing the line, think about the vehicle coming to rest, sides or top, you don't want fuel coming out of the vent line.
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here is a link to a typical tip over valve (check ball). this mount in the tank (usually access thru the filler cap to install, or pre install during fabrication of tank if you what to mount vent near the front of the tank). the line connecting to the tip valve should have a loop or coil in it to minimize siphoning.
http://www.summitracing.com/parts/sum-g3114/overview/
hope this helps
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Thanks all and especially RaceEngineer.
That's the one. I'll order it tomorrow. :cheers: :cheers: :cheers: :cheers:
This component is a critical part and all the help and advice is invaluable.
I'm not known for being a sissy but fire really scares me.
Just watch the overkill on this one. I keep saying this and
guys are probably tired of me but without the members here
this car wouldn't be, period.
Mike.
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I have a set of drawings when I asked for help with venting my fuel cell and I have yet to find them. :roll: Here is some discussion by JackD that describes the routing that works for landing on every side except nose which is not likely. I ran mine out the top center access plate, to the left and down that side, across the bottom, up the right side and continued up and forward to meet the factory vent system running to the front of the car. In the event of not being on it's wheels no fuel will run out the vent from a full tank. The level in the vent line will never exit as there is always more line higher than the level in the tank. I used 1/2 inch aluminum tube from the home center and bent it with an external spring and electrical conduit bender then flaring the ends to AN fittings.
JackD
Check valves are a good start but if you route the vent line out the top, around to the right and across the bottom to the left, what part is not on top above the fuel level in any rollover upset ?
Even if you stand it on it's nose, with the line routed from front to back as it goes around it will work where a check valve won't.
I have a check valve at the tank and hope to never test the system.
Geo
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Thanks Geoff, good advice.
What size vent lines should I use?.
The guys building my tank want the weld in male bungs
and I only have Dash 10 here.
Should I use those or go to an 8?.
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Only flowing some air to equalize pressure, a #4 or#6 should be sufficient for gas, #6 or #8 for fuel.
Ron
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Ron, thank you.
I'll be running Ethanol and have some #8.
I'll go with that. God Bless. :cheers:
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You haven't lived until you've been on fire at least once! :-D
Sid.
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Been there, done that. Definitely don't recommend the experience. :x :x :x
Pete
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That's not on my bucket list of things to do. :-o
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Sid, do workshop incidents count?.
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Sid, do workshop incidents count?.
Uhhm, well they do in the world I live in.
"Accidently", and stupidly, set my clothing on fire once while cutting with an oxy-acetylene torch.
Can't recommend the experience . . . .
:cheers:
Fordboy
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A weldor one time told me, if you smell smoke while cutting or welding, stop and put yourself out. :-D :-D
Ron