[Government welder]

Good evening folks. I've recently took up Tig welding I've learned alot from watching videos and am going to build a fuel transfer tank for about 20 gallons out of ss and looking on advice. If someone could lead me the right direction sure would appreciate it

[Poland308]

How thick of SS are you thinking of using? Any requirements on dimensions?

[WeldingJunkie]

Stainless is a tough metal to learn on. make sure you have your Argon set higher than Aluminum and your heat set lower than you would with Aluminum. You may need to purge if you are going for air tight.

[Government welder]

Sorry I lost the post and to be honest started working on the honey do list for a while just know getting back to designing the tank was think of using 14 gauge stainless with two baffles thinking now more like 50 gal tank first question is should I weld the inside and outside im think of making the box and then a bolt on sealed lid so I can get it apart if cleaning or any other add one down the road

[Poland308]

If your looking for maintainability then your plan is a good one. Might consider using 1/8 for the bottom. Probably going to wear out first from rubbing. With a bolt off top you will be able to clean it out for any needed repairs, inevitably every fuel tank will crack at the seams.

[tweake]

i havn't done steel tanks, only aluminium.
i like to weld inside as well as out, especially on the bottom and sides. that just helps with sealing, bulks up the joints, especially as aluminium is a bit weak. i don't like any gap where a bit of crud can work its way underneath as the tank flexes, which then becomes a stress riser.

keep in mind the design. easy to strengthen it by using baffles as supports. but a removable top reduces it strength.

[Government welder]

Thank you I've noticed that most tanks you buy are plain steel which I'm assuming the do to reduce cost but with that you end up with rusty tanks. I know that aluminum doesn't like flex and it being prone to cracking is why I was thinking stainless. I will at a few baffles and a bolt on lid to be able to clean it out if need be or at least a decent size hole in the the top. I've got a box and pan was thinking of making sides and bottom one piece and weld the corners thought also about adding angle inside the corner to add some strength but worry about lack of fusion in the root of the seam.

[cj737]

A stainless tank will be heavy. Very heavy compared to ally. You also really need to run a backside purge while welding stainless, tricky to do on a large box. But not impossible.

I have made small purge fixtures for inside and outside corners by using large ally angle iron and some flat stock. Then I thread a hole for a Quik Connect. I usually make sure the purge area is at least 4” long so I can weld that much, pause, and move to another area. Stainless really likes to move A LOT during welding.

I would fuse weld from the inside. You should be able to get full penetration with a purge and prevent any sugaring.

Ambitious undertaking, interested to see how it goes!

[Government welder]

I like the angle and flat purge block. I'm going to build a tank like the one in the picture and a smaller one to sit on the base of the larger one .I was thinking 14 gauge as with baffles to help some with the weight. I sticked one in the past not knowing anything about the sugaring effect.mostly I'm doing this for the fun I forgot how much I enjoy tigging. I truly appreciate everyone's thoughts and such

[tweake]

you can just use an alloy angle iron as a chill block.
the big thing i find is having really good fit up makes a huge difference.

unfortunately working with stainless is just expensive.

[Government welder]

Would y'all recommend folding the box shape or have each piece cut it will get cut on a plasma cutting table

[tweake]

Would y'all recommend folding the box shape or have each piece cut it will get cut on a plasma cutting table

fold as much as you can.
every cut and weld adds errors.
that may sound strange on a welding forum but for a good finish, the less welding the better especially if its prone to warp.

[Government welder]

That was kinda my way of thinking on it I m trying to get a grasp on all the as options out there I didn't realize there was so many

[Government welder]

So I got my metal prices today and really wasn't a big difference in price as I thought there would be. I'm scared of the aluminum cracking over time but the stainless will cost me more in gas for purging so so I've got some things to weigh and see what happens

[cj737]

So I got my metal prices today and really wasn't a big difference in price as I thought there would be. I'm scared of the aluminum cracking over time but the stainless will cost me more in gas for purging so so I've got some things to weigh and see what happens

Both materials are susceptible to cracks in the joints. Aluminum is lighter and id say easier to weld in this application due to a purge requirement.

Plus, you can easily weld the inside and outside of the joint on the aluminum and greatly reduce the risk of cracks.

[tweake]

So I got my metal prices today and really wasn't a big difference in price as I thought there would be. I'm scared of the aluminum cracking over time but the stainless will cost me more in gas for purging so so I've got some things to weigh and see what happens

Both materials are susceptible to cracks in the joints. Aluminum is lighter and id say easier to weld in this application due to a purge requirement.

Plus, you can easily weld the inside and outside of the joint on the aluminum and greatly reduce the risk of cracks.

i'll argue aluminum is a bit weaker, so you use thicker material and a stronger design.

[cj737]

Both materials are susceptible to cracks in the joints. Aluminum is lighter and id say easier to weld in this application due to a purge requirement.

Plus, you can easily weld the inside and outside of the joint on the aluminum and greatly reduce the risk of cracks.

i'll argue aluminum is a bit weaker, so you use thicker material and a stronger design.

True, but even thicker, the ally is very likely to be lighter and a better choice for this application.

[Government welder]

So my thought was if I went went all it would be 1/8 and as probably 14gauge which is a 2 lbs and some change difference. I do feel that stainless is stronger by nature and they both have their ups and there down. I don't know how much more argon I would need for the purge of each joint. One concern I had was if I choose stainless I would weld the inside joint first. My thought was if there was any sugaring it would be much easier to correct with grinding out the joint. I will put at a minimum of 2 baffles in which ever one I decided. I'm going to build 2 one will be in a l shape for diesel fuel the other will be a cube shape that will be able to sit on the base of the L to help with storage space is my thought they will also be able to be picked up separately in case one only need to be filled

[tweake]

Both materials are susceptible to cracks in the joints. Aluminum is lighter and id say easier to weld in this application due to a purge requirement.

Plus, you can easily weld the inside and outside of the joint on the aluminum and greatly reduce the risk of cracks.

i'll argue aluminum is a bit weaker, so you use thicker material and a stronger design.

True, but even thicker, the ally is very likely to be lighter and a better choice for this application.

if its was me i would do ally because stainless kicks my arse regularly.
i just finished a couple of stainless pipe fittings and shes not pretty to say the least. 1/16" 2" dia tube is just small and fiddly.
however some improvement was made.
stainless love gas, chewed through lots.
don't forget the post weld clean up and passivating.

[cj737]

So my thought was if I went went all it would be 1/8 and as probably 14gauge which is a 2 lbs and some change difference. I do feel that stainless is stronger by nature and they both have their ups and there down. I don't know how much more argon I would need for the purge of each joint. One concern I had was if I choose stainless I would weld the inside joint first. My thought was if there was any sugaring it would be much easier to correct with grinding out the joint. I will put at a minimum of 2 baffles in which ever one I decided. I'm going to build 2 one will be in a l shape for diesel fuel the other will be a cube shape that will be able to sit on the base of the L to help with storage space is my thought they will also be able to be picked up separately in case one only need to be filled

Welding inside first with a purge on the outside is fine. But, when you switch and weld the outside, the internal weld will get reheated and you run a real risk of overheating it. With or without a purge. That’s the sort of thing Tweake is posting about; how tricky welding stainless is.

If you do stay the course, weld only from one side with a slight gap and get full penetration in a single pass. Then passivate it afterwards.

[Government welder]

Oh well that's very helpful information these are the things that only experience can give you I truly appreciate it

[Government welder]

I will be making the tank out of 3/16 aluminum plate got a great deal on a 4x10 sheet it has some oxidation on it from sitting outside but I'm going to cut all my pieces and clean each piece and ensure all seams will be very clean.

[cj737]

That will take some serious amperage to weld. A 200amp machine can do it, but I’d run some helium in your gas mix and use a 1/8” tungsten. Lots of tacks, both sides will help prevent warpage while welding.