precautions to be taken when welding a gasoline tank

admin

This guy wants me to weld his motorcycle tank and I would like to know how to prep the tank before I weld it up. Don't want some kind of explosion from fumes or something like that. Anyone done this before? Thanks.
Reply:Uh-oh, here we go again...  Prepare to get way more responses than you want...
Reply:Originally Posted by TubularFabUh-oh, here we go again...  Prepare to get way more responses than you want...
Reply:That's ok. I would rather have to many responses than none at all.
Reply:Updated your will.
Reply:do you have pics ??? it needs to be clean hot soapy water several times or vatted out mostly done by brasing or silver solder or tig if clean enough i would inspect  it very well  if we could have more details on it  would help you could do a search for the others that have been posted i would go with O/A braze  but if it is rusty you may be better off  looking for a replacement new/usedidealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441
Reply:i have to weld on half dozen motorcycle tanks a year........so that about 60 tanks i've welded on in the last 10 years.........the pros here are going to tell you i'm wrong.....but i repair and paint professionaly day in and day out....so maybe it's time for me too learn.- fill it up with water........then drain it. -if your going to be doin' alot of tig welding onit , it's good to purge it with argon.after you've welded on it ........u must pressure check it. -tape up all holes real tight with masking tape......pressurize the tank withbout 10 psi.....and check all welds and seams with windex if u put too much compressed air in it.....it will almost turn inside out..it will destroy the gas tank..DO NOT LET THE PAINTER GRIND THE WELDS LATER OR YOUR PAINT WILL BUBBLE AND THE TANK WILL LEAK AND LIFE WILLSUK.        thermal arc 252i  -  millermatic 350P -   miller XMT, cp300ts, 30a 22a feeders, buttload of other millers, handfull of lincolns, couple of esabs  -   Hypertherm 1250 G3
Reply:10psi?????  You'd better check your gauge.  I've seen a good tank (not repaired)  deform at less than that.My name's not Jim....
Reply:Originally Posted by Boostinjdm10psi?????  You'd better check your gauge.  I've seen a good tank (not repaired)  deform at less than that.
Reply:Originally Posted by nimzoxThis guy wants me to weld his motorcycle tank and I would like to know how to prep the tank before I weld it up. Don't want some kind of explosion from fumes or something like that. Anyone done this before? Thanks.
Reply:And if it's just pinholes JB weld works wonders and I even put on patches with it... so that's a safe alternative as long as it's clean and not in two pieces LOL my 2 centsLincoln 225 Tombstone,Miller Big 20,Hobart 180,150' Argon,A/D hobart hood 22 Ton Log splitter,79 F350 dump eats 4.75 TONS and still turns cutters,grinders,And a  Hypertherm POWERMAX 30
Reply:Originally Posted by dave powelson(The approved, safe ways--are not the methods embraced by most of the 'experts' on thisforum who blindly proclaim 'this is how we've always dun it'-- ignorant of the chemistry andphysics involved.
Reply:Cutting corners, and welding gas tanks "on the cheap" is a sure way to a booming business.  (Pun intended).
Reply:Originally Posted by Tony DAnd if it's just pinholes JB weld works wonders and I even put on patches with it... so that's a safe alternative as long as it's clean and not in two pieces LOL my 2 cents
Reply:Originally Posted by woi2ldthink maybe a gave too quick of a description up there on how i do it ,when i can probably type a small book on here...also thought i was  a googlaholic ....maybe it's trade secret , know accurate stuffs hard to find on this topic and who am i to give advice.......i'm an expert who fixes  the Pros mistakes Professionaly !  i'm here to learn and hang' with u guys , i dont wanna build myself up yet , you'll think i'm a liar , then slowly realize tha truth of my experience.............like i said , i wanna learn..........and i'll tell ya what i know.
Reply:Welded a cracked stretched Harley tank today. Don't do a whole bunch but have welded several. ID problem area, clean, purge, weld, test. But I would have trouble describing exactly how I do it. So don't try. If you can get someone that has experience to show you then try the next one.Add your location in your headding, someone close may be willing to help.Peter
Reply:Another thought is to use a tank sealer product to fix little pinholes and such. Clean out the tank, pour in the sealant, and slowly roll the tank around.... follow the directions to the 'T'. This works, and is a good way to go with a questionable rusty tank. If the tank is shot out, the minute you add some heat, it will start to fail much worse; rust pops, small cracks, or even a spot just collapsing the minute you hit the arc or torch on it. I have seen all the above, plus the errant 'Whoomp'....( More than one of you knows this sound personally also!!!). At times, a sealer is a good option. For a pressure test, if you plan to run a regulator that is not precise, I suggest leaving a small vent OPEN so you do not over-pressurize the tank. Get a squirt bottle with soapy water in it to test the whole thing, and go slow with that air. I use 2-3 PSI on most tanks, some bigger, high strength tanks (3/16 aluminum) will get 5-10, but not sealed completely; 10 PSI can really bulge a tank if it is not baffled inside.Last edited by Rojodiablo; 03-17-2010 at 10:15 PM.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:mr. dave powelson , markd' one of your interesting threads before, so i'd already knew u were one of the more intelligent guys in this forum...so i treaded lightly , not to be trampled under the soles of another mans shoes.i allready understand that ,  bet others dont , and was not so poeticly able to explain as such......not really lamans terms genius , but so glad u are here.        thermal arc 252i  -  millermatic 350P -   miller XMT, cp300ts, 30a 22a feeders, buttload of other millers, handfull of lincolns, couple of esabs  -   Hypertherm 1250 G3
Reply:Steam is the best and safest way to weld on anything that has contained an explosive or flammable liquid. High volume low pressure steam and it needs to stay hot. Make sure the tank is grounded and use brass tools as they are non sparking unless to can verify the LEL content of the air inside the tank. LOL ive heard of guys using a hose from a tailpipe off of a running vehicle to purge the air. I would say that nitrogen would be your next bet. Never use more than 5 psi as you could damage the tank and you create a hazard using more. You could always drop a match in there, if you dont blow up your prob good to go. If it is just a crack, I think then sell a putty for these types of repairs.
Reply:oh as for leak testing you can pressure it up and use soapy water or fill it up with gas again and let it sit overnight then check the repair again as gas is thinner than water it will leak faster. But if there is still a leak the soapy water is easier to work around
Reply:WDH is right STEAM is the safest way to purge a gas tank or any other tank with volatile fumes or vapors.  STEAM is the only way to do this.  GET IT. good hot dry steam.  A cycle tank should take about 15 minutes min.be sure to turn tank upsidedown so the condestate (water) can drain off.After purgeing the tank is safe to weld on.Larger tanks take longer time to purge. Car and truck tanks as much as 1 hour or more.      I know it might burn the paint job on a cycle tank. I have done many with out any problem.