I need to weld legs onto a propane tank processor that will hold about 150 gallons.
The legs (4) will hold the tank about 3-4' off the floor. What size steel pipe or angle to use? I see these thin steel stands that are holding up 250 gallon oil tanks outside houses and man they sure don't look like they should be holding up that much weight.

I have a cheap 120v mig welder that I have been using with flux core wire but it sure is alot harder to weld with than the stick welder we used in shop class many moons ago. Any pointers for how to use this thing? The legs I put on my other Propane processor were scrap 3" angle but the welding was a mess. This time I'll have to purchase the steel.

Thanks in advance,

First off the 120V welder you have will not have the wheaties to get adequate weld penetration for that task that you need it for.

Flux core also is just for thinner materials that would warp from excessive weld heat. I'm sure there are those who, with more experience, will say that a 120V welder will do that job. But, in my experience the 120V welders are best for autobody work rather than structural steel.

150 gallons of any liquid will carry a considerable weight. I wouldn't use anything less than 2" angle or square tube. Be sure you get a reasonable wall thickness that can handle the load. Give yourself enough safety factor, you don't want one of those legs to be a weak link in your system.

When you weld with a MIG, take your time, test out out your weld settings on a similar piece of scrap steel. And get comfortable physically, if you're uncomfortable or bent all around, the weld quality will suffer.

Are you going to anchor your tank to a foundation pad of some sort? I certainly would recommend it if you're going to have that tank 4' off the floor, the center of gravity will make it top heavy.

Just some thoughts and suggestions. I've build similar tank system and safety was always paramount.

Hi Double D,
150 gallons= 1000+ lbs, and those domed propane tanks are bears.
If your tank is still barebones, I'd get some 3"x 1/4" thick angle, cut them to length, notch them
where the dome is welded and take it to a weld shop or a friend who has a gas shielded 220V machine. You'll probly need to convince them that the tank wont blow propane fumes.

You probly have .023 wire, and even a triple pass might not be adequate for safety, especially if you only hobby weld. Prepping and cleaning is vital for a good weld. Ive seen cold welds that were pretty, but snapped clean away from one of the steel parts.

I understand the desire to do it yourself, But if you take it to a shop all prepaired to where the welder cant just zap out the job in minutes, he might do it very cheap- below the 1 hr rate. I'd do it for 6 pack. . And the weld would be rest assured. They may even do it right away.

Even better, do all the layout and go ahead and tack it all in place with your 120V. 4 legs wouldnt take 15 minutes to weld on since all the layout and clamping is bypassed for him/her.

I've had 120V welders that would do it, a Snap-On mm140 and Lincoln sp135, both on gas and .025-.030 wire. The model numbers often represent the amperage or close to it. Even with those machines, I'd probly triple pass it.

I'd make some feet plates for it as well. And RedHead them into concrete.

Shoot me some pictures when you start building, love to see em.

HTH
Brian

Just 4 straight legs no more than 30 inches between floor and contact point on the tank,
2 x 2 angle iron @ 1/4 thick or 1.25" Black Iron Pipe

thanks for all the info guys,
I saw steel angle at work today that I may be ablr to use. some of it was 2" and some others were 3"x6" +/- lintels left from some old jobs.
I'm thinking I may bring the legs down plumb with the outside surface of the tank and weld the angle to the radiused section (dome) so that no angle protrudes out wider than the tank. That would allow me to be able to bolt 4 pieces of flat steel to the legs up to tie them all together. Just in case.

Would shielding gas help weld penetration?
How about heating the piece with a torch prior to welding?

Brian,
It would be best to take it to someone but... that's the professional in you.

quote:

Would shielding gas help weld penetration?
How about heating the piece with a torch prior to welding?

Brian,
It would be best to take it to someone but... that's the professional in you.

D,
Dont get me wrong, mig welding is easy, my little girls have learned it just by being around it
- I am no instructor, by any means- and I'm self taught.

If you own a machine, Im confident you could do it yourself, I just dont think your machine could produce the heat needed for .25" thickness. Can you borrow or rent a higher amp welder?

Not trying to make you spend money or belittle your skill or equipment, Brother.

Gas or Flux core;
Ive used fluxcore w/.o45 on .5" plate. It's great and makes a pretty weld. So hot, the slag will just curl up behind your weld as you go. These were like 300amp 3ph machines. And had Co2, I believe.
Gas is probly the most common preferred setup. More economic? IDK. Ask fabricator, I'm just a designer and employer.

IME, Ive only used a rosebud torch on steel that has been outdoors under ice, to run off the moisture.

Brian

I bought one of these cheapo Wolf flux cored welders (sold under the name PowerCraft)and its been great, and I've welded some pretty thick steel with it no problem, and I'm a complete beginner regarding welding. However it runs at 240V, not 110V. After I bought it I read some pretty bad reviews and cautions not to go near them, but I think these were all out of date as the welders seem to have been upgraded and improved a lot. It only cost me £100 a year ago and its been a great buy.

You can cheaply modify your welder to work as a stick welder as well as a mig welder. (you didn't hear this from me)

But first -- I do a good bit of welding on propane tanks, be sure you have cleaned them out by filling them with water to overflowing, there is always a bit of thin flammable oil settled on the bottom, this should float out on top of the water. I keep them full of water when I weld or cut on them, at least until I have a 6 inch or larger hole in the tank to let it "chuff" (still damb scary) rather than explode if there is anything flammable left inside.

80 amps will allow you to make light passes to weld 1/4 inch stuff to these 90/1000 thick tanks fairly well if you use the small 3/32 diameter rod, 1/16 diameter rod sorta works but it is expensive and at 80 amps it tends to glow red and burn off the flux coating if you stick it. 6010 or 6011 stick rod will give you a bit better penetration but it splatters a good bit, 6013 rod will make a nice smooth weld but won't penetrate as deep as the 6010-11, I use 3/32 6013 rod to weld 2 inch steel pipe nipples to 5 gallon BBQ propane tanks when making barrel funnels out of them. Small rod diameters will make smaller weld beads so make more than one pass with the 6010-11 first then cover them with 6013 if you want it to look nice, otherwise the 6010-11 is fine by itself, or also try 6013, it is much easier to weld with (MUCH easier, hardly any sticking and flows like butter) and the weld should be more than adequate if you do a reasonable job of running the bead. (Keep ALL rod dry while storing it or it likely won't weld worth a darn even after it dries out)

OK, the conversion - Your 120v mig welder is just a small buzzbox with the wire feed added, you can add an additional #4 welding cable with a small cheap stick rod handpiece to the output of the power transformer (or diode pack if the welder is DC, (not likely)). There should be a lug with a heavy wire from the transformer attached to the metal thing that the wire from the mig spool slided through just before it enters into the tube that goes out to the mig handpiece, leave the transformer wire connected to the lug and add the new stick welding cable there also, now you have a double duty welder. If the wire speed feed control does not completely stop the wire movement you will need to also release the tension on the small feed wheel that pushes the wire out to the mig handpiece.

This will definitely void your warrenty - so - your choice. The particular welder may, or may not, have a way of adjusting the output amp setting. any of these small 120 volt welders have a duty cycle time limit for the amount of welding you can do before they overheat. The internal big transformer will get pretty warm if used to weld very long so test it and find it's limit. Getting 80 welding amps out of one of these 120 volt welders will take 15-20 amps from the wall outlet so you may blow a circuit breaker occasionally, it is also not a good idea to use a dropcord, but if you must, it should have AT LEAST #12 wire, #10 would be much better, anything smaller and everything will overheat and it won't weld worth spit due to low voltage (it will do heavy welding even worse than any of these little machined normaly do).

Tim,
Man that is kewl. I may have to give it a go.
My machine does have variable power settings with the highest setting indicating it requires a 20A breaker I beleive.
It is 120V AC.

Thanks for all the pointers guys it certainly helps.