Welding Gas Tanks

Hey guys!

its been a long time and I´ve been super busy with welding!Did a lot of different welding,mainly stainless.

Now my next project will be practising low amp TIG brazing on a moped tank I have laying around...
How do you guys purge your gas tanks before welding?

The tank is laying around nearly 4 years open without gas in it in my workshop.

Thanks in advance!
 
Ryan Stecken said:
Hey guys!

its been a long time and I´ve been super busy with welding!Did a lot of different welding,mainly stainless.

Now my next project will be practising low amp TIG brazing on a moped tank I have laying around...
How do you guys purge your gas tanks before welding?

The tank is laying around nearly 4 years open without gas in it in my workshop.

Thanks in advance!

a couple thorough rinses with warm soapy water will help, then to be safe you could purge the tank with an inert gas, such as argon or c02. If there is no oxygen in the tank, there will be no boom. Remember when purging, you don't just fill the tank with inert gas and call it good, you have to have gas flowing in and out. Like using masking tape to plug the filler hole with a nail hole punched through it and an inlet line running in through the petcock hole. Also, remember if you were to use argon to purge it, Argon is heavier than air, so the vent hole needs to be at the top. At times you still have to thing of gasses as liquid, so you would need to fill the tank with the heaver "liquid" from the bottom and have it "overflow" through the top.

Also, an aside on tig welding and pre weld cleaning in general.....

DO NOT USE ANY SORT OF CHLORINATED CLEANER!!!!!!!

commonly seen in aerosol brake cleaner.

Chlorinated brake cleaner at intense heat (I.e. welding) creates Phosgene gas.

There have been several cases of death and serious neurological damage.

Its a common issue in home shops, as it is at times the first thing youd think to grab to "get this oil cleaned off real quick before I weld it"

Sorry for the side track, but I fell its important information to get out there.
 
Thanks guys!

I´m using only acetone to wipe down the stuff I weld,made a little welding class where the teacher already advised us NOT to use brake cleaner.

I think there was a misunderrstanding,I´ll ask the question again:

-How do I get the residual gasoline out of a gas tank the best way before welding it?

Is it necessary to backpurge with argon when I´m welding on a steel gas tank?I guess yes, since the penetrating seams need a good shield too...
 
Ryan Stecken said:
Thanks guys!

I´m using only acetone to wipe down the stuff I weld,made a little welding class where the teacher already advised us NOT to use brake cleaner.

I think there was a misunderrstanding,I´ll ask the question again:

-How do I get the residual gasoline out of a gas tank the best way before welding it?

Is it necessary to backpurge with argon when I´m welding on a steel gas tank?I guess yes, since the penetrating seams need a good shield too...

a couple rinses with hot soapy water should really do well enough to get the residual gas out. The back purge on mild steel would be more to get any gas fumes out for safety more than a necessary means for getting a proper weld on mild steel. If it were stainless, yes a back purge is needed, on mild steel it is not required
 
Hurco550 said:
a couple rinses with hot soapy water should really do well enough to get the residual gas out. The back purge on mild steel would be more to get any gas fumes out for safety more than a necessary means for getting a proper weld on mild steel. If it were stainless, yes a back purge is needed, on mild steel it is not required

Thank you hurco!
Will do!

Any hints on how to approach the thin wall metal on the gas tanks...I will use a moped tank to practice my welding skills.

I will try to keep the heat away from the metal as best as possible, so I´ll be more "brazing" than welding.
I guess I will start with low amp (20-40) with a long stroke pulse and work my way "up".

I bought a gas tank that is leaking and I guess I will try to reweld a cracked seam thats leaking....
Already welded thin wall stainless and the trick was not to form a puddle but more to melt the stick and than move the material around...
 
In my limited experience, the trick is to control heat and with a tank that means tacking it and then doing more tiny tacks until the tacks basically all join up. What I am trying to explain is that with lots of tacks the whole seam is connected. If you start putting too much heat it without lots of tacks, the metal distorts and gaps open up and they take more heat to close and that causes more distortion.

And wash the tank with hot water before you go near it with heat.
 
teazer said:
In my limited experience, the trick is to control heat and with a tank that means tacking it and then doing more tiny tacks until the tacks basically all join up. What I am trying to explain is that with lots of tacks the whole seam is connected. If you start putting too much heat it without lots of tacks, the metal distorts and gaps open up and they take more heat to close and that causes more distortion.

And wash the tank with hot water before you go near it with heat.

Thanks teazer!
Will do!

I will practice this weekend and let you guys know the result!
 
I like to use silicon bronze filler rods for welding on tanks.
It melts at a lower temp than the base metal and you're basically brazing but it works amazingly well for thin metal.
https://weldingsupply.com/cgi-bin/einstein.pl?PNUM::1:UNDEF:X:SILBR33236
 
indeed. Lots of tacks. I've never tried silicon bronze filler rod, but generally I'd advise against using anything but the material the tank is made from. The reason is that any sort of solder or brazing creates a problem if you discover you actually need to weld in that area. Of course, if you expect this will never be an issue, no problem. It's just a rule of thumb for me as I have had a couple of instances where I had to repair something that had been previously brazed.

I've welded more gas tanks than I can remember - seems like mostly they had gas in them fairly recently. I think the risk of explosion is over rated if you use a little common sense. Certainly purging the environment of oxygen solves the problem, but it's easier (not to mention a lot cheaper!) to simply remove the fuel. You can just pour it out and dry the tank, but there is a possibility there might be some small joint or seam holding a bit of gas. You can heat the tank up with a heat gun to drive any liquid into a vapor (it doesn't take much) if you are concerned. I throw in some alcohol (which mixes with gas) and then rinse with water (which mixes with alcohol), then dry with compressed air to keep flash rust to a minimum.
 
jpmobius said:
indeed. Lots of tacks. I've never tried silicon bronze filler rod, but generally I'd advise against using anything but the material the tank is made from. The reason is that any sort of solder or brazing creates a problem if you discover you actually need to weld in that area. Of course, if you expect this will never be an issue, no problem. It's just a rule of thumb for me as I have had a couple of instances where I had to repair something that had been previously brazed.

I've welded more gas tanks than I can remember - seems like mostly they had gas in them fairly recently. I think the risk of explosion is over rated if you use a little common sense. Certainly purging the environment of oxygen solves the problem, but it's easier (not to mention a lot cheaper!) to simply remove the fuel. You can just pour it out and dry the tank, but there is a possibility there might be some small joint or seam holding a bit of gas. You can heat the tank up with a heat gun to drive any liquid into a vapor (it doesn't take much) if you are concerned. I throw in some alcohol (which mixes with gas) and then rinse with water (which mixes with alcohol), then dry with compressed air to keep flash rust to a minimum.

I disagree, as I would just use the sil-bronze to weld in that area :D
Regardless, give it a go for the fun of it, it's great stuff and a ton of fun to weld with.
 
I've welded a lot of gas tanks over the years, and although I have both mig and tig, I still prefer oxy/acetylene. I use a #6 tip with a slightly oxidising flame and tack every 30mm or so with just a dab of filler rod, and use a dolly and hammer to ensure that the joints are perfectly matched as I go. Once that is done I just fuse weld the joint from start to finish which, although not the prettiest from above, gives really good penetration. I like the O/A as it is really easy to control the weld puddle with speed and tip distance.

I've just finished narrowing a CB450 tank and it came out OK. The steel is 0.8mm thick (0.032") which is really quite thin but still workable.
https://i.imgur.com/hMfSen7.jpg[/IMG]]

A close up from above shows the finished fused weld. There is virtually no bead there so minimal finishing work is required
https://i.imgur.com/Ex1a9s1.jpg[/IMG]]

A close up of the underside showing the penetration
https://i.imgur.com/M59JhaS.jpg[/IMG]]

A view looking across the top showing very little distortion.
https://i.imgur.com/oUqFrzE.jpg[/IMG]]

With regards to preparing the tank for welding I pretty much do what has been mentioned, but lastly I sit the tank on the ground with the fuel tap out and fill it with water through the cap. I then get the O/A torch and put it in the top of the tank, gradually lowering it as the water level drains off. This flashes off any residual fume safely, as the initial volume is very small.

I'm not a welder by trade, but this is just what I do. Just my 2c worth....
 
Ryan Stecken said:
Hey guys!

Its been some time since I posted,i´m totally lost into the welding :)

I try to weld as much as possible but the last days since we have a an oldschool brass workshop I started to TIG weld casting mistakes out of our brass objects.
I also started to practice stainless which is VERY VERY rewarding and easy to weld.

Since brass is quite poisonous to weld (zinc and lead burning of) I built a welding cart so I can move my welding machine to another room of the workshop where we have an extraction system and a window.Still need to cut out a piece of my welding mask in order to fit my respir mask :D
What mask are you using? My 3m respirator fits under my Miller welding helmet.


Sent from my iPhone using DO THE TON
 
guzzi850t said:
What mask are you using? My 3m respirator fits under my Miller welding helmet.


Sent from my iPhone using DO THE TON

I´m using a SR200 Stundström full face mask with an ABE1 filter...really perfect mask that...you never ever taste or smell anything it seals off perfectly!
 
Ah I can see how that wouldn't fit under the welding helmet. Nice mask, perhaps if there was a hose with a remote filter or supplied air. That's what I really want next is a supplied air setup. I can always taste the cut off wheel ...


Sent from my iPhone using DO THE TON
 
#6 tip! I use a 000 for thin metal. I suspect I could use a larger tip with lower gas pressures though. For 22 gauge expansion chamber cones the tiny 000 worked fine.
 
teazer said:
#6 tip! I use a 000 for thin metal. I suspect I could use a larger tip with lower gas pressures though. For 22 gauge expansion chamber cones the tiny 000 worked fine.

Hi Teazer, I'm in Australia and our #6 tip is 0.6mm diameter and I believe your #000 is 0.559mm, so we're really quite close. I weld with a very slightly carburising flame but also find the #6 tip very handing for cutting body steel but adjusted to a highly oxidising flame.
 
Pete12 said:
I've welded a lot of gas tanks over the years, and although I have both mig and tig, I still prefer oxy/acetylene. I use a #6 tip with a slightly oxidising flame and tack every 30mm or so with just a dab of filler rod, and use a dolly and hammer to ensure that the joints are perfectly matched as I go. Once that is done I just fuse weld the joint from start to finish which, although not the prettiest from above, gives really good penetration. I like the O/A as it is really easy to control the weld puddle with speed and tip distance.

I've just finished narrowing a CB450 tank and it came out OK. The steel is 0.8mm thick (0.032") which is really quite thin but still workable.http://A close up from above shows the finished fused weld. There is virtually no bead there so minimal finishing work is required
[url=http://[img]https://i.imgur.com/Ex1a9s1.jpg[/IMG]]

A close up of the underside showing the penetration
[url=http://https://i.imgur.com/M59JhaS.jpg]https://i.imgur.com/M59JhaS.jpg

A view looking across the top showing very little distortion.
[url=http://https://i.imgur.com/oUqFrzE.jpg]https://i.imgur.com/oUqFrzE.jpg

With regards to preparing the tank for welding I pretty much do what has been mentioned, but lastly I sit the tank on the ground with the fuel tap out and fill it with water through the cap. I then get the O/A torch and put it in the top of the tank, gradually lowering it as the water level drains off. This flashes off any residual fume safely, as the initial volume is very small.

I'm not a welder by trade, but this is just what I do. Just my 2c worth....
[/url][/img]

I'm lousy with welding tip numbers but isn't a 6 pretty big? I also use a 0 or 00 for thin stuff. You gotta be working super fast not to be burning holes with a 6?
BTW, came out pretty nice looking in my opinion.
 
crazypj said:
I'm lousy with welding tip numbers but isn't a 6 pretty big? I also use a 0 or 00 for thin stuff. You gotta be working super fast not to be burning holes with a 6?
BTW, came out pretty nice looking in my opinion.

Thanks crazypj.
I'm in Australia and our #6 tip is just a little larger than the American #000, so it really is quite a small tip.
 
So guys go slower with me here :)
Are you guys talking about oxy torch setups here and tip sizes?
Since I'll be alot into bending metal the next year i'm thinkinh hard on getting an oxy setup in my workshop...
What do I need for oxy brazing/welding?

Thanks

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