Weld Repair on a Gas Tank 

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I'm glad the algorithm decided that I needed to see this channel. Super informative, and the anecdotes from other welders in the comments about their similar experiences are super cool.

Nice job. I have on SOME situations were I stitch or stack the weld with mig. Then gone back and washed the weld with the tig. It smooths out the stitch and helps ensure a good connection to the thinner metal.

I have welded 3 motorcycle tanks that had small rust holes on the bottom. Drain completely. Allow compressed air to turbulate inside the tank for several minutes. Tape rust holes and fill tank 1/2 full of dish soap/water mix. Shake with vigor for several minutes. Drain. Refill with water completely to brim. Install fuel cap. Turn tank over to expose damaged area. Remove tape and allow a small amount of water to drain away from rust holes. Sand area with 80 grit for shiny metal. Apply flux. Silver braze holes closed using miniature propane pencil torch. I never had this method cause bark- back or fire.

I was a certified welder for years. Used to weld cracks up in Exxon tank trailers everyday. The trailers would be steamed out at our shop overnight. Before allowed in the shop. Then an explosion meter was used to check for pockets of vapor gas. Then on to fixing. Keep in mind. People like me also repair Milk tankers that carry the milk you drink. Now that takes a whole different type of protocol to repair.

When I do gas tanks of any kind, I thoroughly wash and dry them. This usually takes care of 99% of the hazard then I inert the tank with argon, CO2 or throw a chunk of dry ice in the tank to inert the tank. Of course if your TIG welding and argon purges probably the best thing to use. Trying to check a gas tank for flammable vapor using any kind of flame is suicidal at best. This also works well for LPG tanks that are being cut open for turning into a smoker etc.

Colleague of mine blew a tank when he put the torch to it without checking it himself thoroughly. Luckily it blew away from him but safe to say he went for a cigarette. He was quite ashamed but it goes to show how quick something can go wrong because he is definitely not someone who does irresponsible stuff like that often

Thanks for the quick cost breakdown at the end

I like the burn the paint off method too. Just be careful not to use it on military CARC paint, the older stuff contains cadmium. Not a good thing to inhale.

Being old and a bit of a perfectionist. I would have cut the tacks away. Removed the bracket. Fixed the leak and then tack welded the bracket back in.

Just had local welder die a couple months ago from a diesel tank repair. She had been doing this type of repair for well over 40 years. Not sure exactly what happened but it is vary sad. She was quite talented and did some welds on the aluminum on my bike.

I've repaired many fuel tanks in the past and never had any problems. I always washed the insides using a hot pressure washer first.

When I was in the Merchant navy, the fuel oil mixing tank (a pressurised cylinder about 4' tall and 1.5' wide, with a plate welded over each end, in which the unused fuel would mix with freshly metered fuel before going back to the engines), split part of the weld afixing the lower plate and sprayed that corner of the engine room with hot, extremely flammable fuel oil. This stuff is like tar, smells like Kreosote and not only flows easier (at all) when hot, but also becomes *MUCH* more flammable. It made a godawful mess of that entire corner of the engine room, but luckily missed the hot exhaust of #1 genny, beside and slightly forward of it, or things would have been a LOT worse We get the fuel shut off, the mess cleared up and any leaking fuel caught while the pressure inside the vessel drops and then, because we're in the middle of the Atlantic and there's nothing else for it, it's time for the fun job…welding this sticky-black-goo-of-agonising-death filled bomb back together. How ever did that engineer survive such a deadly task??? Thanks to iron underpants and an unflappable sphincter about, the only thing he could do was put his faith in science, follow orders and (carefully) stitch it back together with a stick welder, pausing every few seconds so the wiper (his actual job title), who was standing by with a bucket of water and a wet cloth, could clean off any fuel that still oozed from the crack in the welder's path, until it was sealed up tight. Thanks to the upper (UEL) and lower (LEL) explosive limits, the science part in all this, he was able to do so without any (well…much) fear of the whole lot going up in his face because the fuel/air (oxygen) mix was too rich, actually no oxygen at all present in the fuel inside the tank (above the UEL) and the vapour present outside the tank was too lean (below the LEL) with no more fuel oozing out than would cause anything more than the smallest of flames, easily extinguished with a wet cloth, so it could be welded quite safely. Incidentally, this is also the actual reason why piping exhaust gas into a tank works. It displaces any flammable air(oxygen)/gas (petrol) mix and being anaerobic (oxygen free) prevents any liquid fuel remaining in the tank from flashing off and creating an explosive mix in the same way that using Argon, Nitrogen, CO2, etc would. Of course, that didn't stop us all watching with baited breath (while hiding in the control room of course…for safety reasons you understand **ahuh…hem** 🙄) during the entire episode.

Nitrogen is way less expensive than argon and the kids Mr Bubble is the absolute best leak detector. The torch method is my preferred method for paint removal as well. Great video

My father fixes custom painted fuel tanks for a local motorcycle shop. H he boils them out using a steam cleaner then lightly blasts the inside of the tank, pours in metal prep to ensure all the rust pits are treated. Then steams again using a hot air gun to dry the tank. NEXT is tank coating. Which is advertised as filling rust holes and cheesy areas. The manufacturer actually made a tank from the material by using duct tape as the mold. poured cured and then removed the duct tape, filled with fuel for a year, no thinning, no leaking,. Most motorcycle tank issues we encounter are a direct result of ethanol laced fuel in uncoated metal tanks. Ethanol fuel in an ncoated tank, the ethanol absorbs water then through heat cool cycles falls out of suspension, the water nests in the lowest point, rusting the tanks.

Use the Fronius welder next time. I use them at work and they are masters of control.

Great fix! Many bikers aren't in a position where they can do this sort of repairs themselves, so thank You, for taking the challenge! Oh, and I always thought You guys in the US called it the "fuel tap"? Thanks for sharing! 😎🏍

With ethanol bearing fuels, pinholes due to corrosion damage caused by standing water, seem to be a very common cause of tank leaks? Before carrying out any sort of tank repair, it's well worth carefully inspecting the inside of the tank, and checking its condition. In many cases the bottom of the tank, will be badly corroded, and other than cutting out and replacing the tank bottom, any long term weld repair is difficult/impossible, as applying any sort of heat, tends to open up more pinholes. Realistically, any tank that is leaking due to corrosion, can only be repaired by cutting out and replacing the corroded material, or by using a modified novolac epoxy tank sealant, being applied after the tank has been properly prepared. For full chemical resistance, some sort of elevated temperature post cure process must be employed, to ensure the repair material is fully cured. Tank sealants as supplied are far too thin to work effectively, as run off will tend to mean the products tend to pool in the bottom of a tank, and leave other areas with a very thin coating, which often cracks, and allows ingress of fuel underneath the coating. Filled epoxy based sealant, applied at elevated temperature is the solution here, but is more a professional process.

Instead of welding, what I have done with bike tanks is to simply Solder the leak... I have a large soldering iron for sheetmetal work, so no flame. I can patch larger holes with a bit of sheetmetal also. The bracket - would be hard to solder unless it could be removed and the metal under cleaned. But the upside of that would be the much better contact between the bracket and tank (soldering would fill in under the bracket, like glue) It paints and seals just fine also. Great work BTW.

I use Dawn dishwashing liquid works great to get rid of gas fumes Nice repair only thing I would do is drop the wire size to make it a little easier to play with on the thin areas!

Like how you cold welded it or stitch welded it, where you blew through it, lol,but i would have down hilled it,while staying in my puddle and just let it drop,thats just me tho,also you probably could have rotated the tank to get a better angle, welding to me is all about bracing up and getting comfortable, but nice work 👍

Oh interesting way to purge the tank. I was taught a long time ago one way to purge a vessel is to fill it with water up to the leaky area.

Good work brother as always good job and miss shooting the shit at MCRD

as a hobbyist welder and shade tree motorcycle mechanic of thirty years, this video hits the nail right on the head for me. thanks, brother. hope all is well with you 👍🏾

Seriously my favorite welding Channel. I've learned a ton from your videos. Hope to be able to make it out to Vegas and do a class Sunday

If you don't do enough of these repairs to warrant buying special equipment like a steam machine, a shop vac works great, using the exhaust, NOT the suction (if you use the suction you will surely get an explosion as the fumes-and-air mixture passes through the combined fan and electric motor of the machine. It's common sense, but it's gotta be said). This method works great because there's a huge volume of air being blown, and that air is very warm which helps a lot to convert remnants of liquid fuel to vapor. It also helps to use a small enough inlet pipe that flushing air can escape around the pipe at its entry point, besides going out whatever other openings the tank has. Doing this operation with the tank outside in the hot sunshine helps a lot too (weather permitting). Another nice feature is it takes almost none of your time because you can leave the apparatus running for more than enough time to get the job done while you work on other things.

Good job Buddy!!!

If you actually know what you're doing, you can guarantee it. Cut the bracket of like you should. Then weld the tank, grind, and sand, and if necessary repeat till the tank is sealed, and then weld the bracket back in place.

I think brazing with low temp rod like silphos might have been the best solution in this case

Had the same leak on the same tank in the same spot. Welded it and resealed with Redkote. A year later still good 💪🏼

Great job

Back in the eighties a very nice older man showed me how to weld or braze a cracked fuel tank that was still on the vehicle and had about a quarter tank of fuel. He simply put a couple pounds of dry ice in it and welded up a seam leak right in front of me. Over the years I’ve used this method with nothing but success. Just make sure the fuel level is below where your welding so fuel can’t run out of where you are welding and then find oxygen outside of the tank that is full of co2.

Always awesome content.

I always make sure its empty and I'll usually put a good helping of c02 or argon in the tank can't have fire if it doesn't have oxygen

you a the roughest worker iv seen in 40 years.

Wait, so your telling me the shop that forced me to weld tanks with fuel and vapor still in them at threat of losing my job....that wasn't normal?

Fill it with water works. Welded my first car tank when I was in high school after 4-5 rinse outs with soap and water. Tank went BOOM! Welded my 2nd tank 4 years later. I was welding on a 2nd S.S flange I made for a fuel sender. Filled it with water as much as possible. No issues.

Not easy finding 98 Dyna Convertible tank, welding is the best option.

The metal of the tank is somewhat porous and can trap enough fuel to cause an explosion after washing. Inert gas purge is the best way to avoid a potentially lethal accident when welding tanks. This tank is small, the danger goes up with larger tanks. All fuel tanks are to be respected, however.

Would it have been faster and easier to just fill the tank with water? I know thats how guys flush old propane tanks before cutting them open to make smokers.

I have welded on a few equipment tanks. I learned to flush, the fill with water for welding. Being equipment tanks they are steel and usually over 1/8 thick. Used the good old stick welder and the water keeps all combustion away.

Can I ask why you wouldn’t remove the bracket and clean it up?

Sheesh, being both a rider and an aircraft mechanic I would just slosh the tank and the leak is sealed and it also rustproofs the interior.

I tried to clear a tank with a torch once.....The tank hit the ceiling of the workshop and came down looking like a pumpkin haha ooops

Part of the blowthrough problem on a stretch is not only because its thin but its because heating the metal with the weld means as it cools its going to shrink and pull apart on an extreme stretch point. Ive seen guys submerge the tank in water all except the area they are welding to ensure the paint doesn't lift and to keep the tank from warping. Some bike tanks have so much stress that they will twist slightly during welding and not go back on the bike correctly or crack the paint soon after esp the old laquer paint. Big pita.

any bend in a tank (Curvature)is the thinnest part of the metal. It's thicker inside thinner on the outside.

I knew a guy who had his own weld shop. He had done this repair hundreds of times in his life. He must have assumed the tank was clear but it wasn't. He struck an arc and the tank exploded. The flange took off like a missile hitting him in the head, killing him instantly.

that tank was rusted through . not worth fixing will leak again short period of time.

General question, Why not just clean it all up and use a vacuum and metal epoxy to repair such pin holes ? Using the vacuum to pull the epoxy into the hole.

Have you tried to connect a hose to the exhaust pipe of a vehicle and put the gas inside? It is also effective. The advantage is that it does not rust the tank if it is made of iron

Justin, did you ever weld a diesel fuel tank? I think that they are harder to degas since diesel is way more viscous and les volatile. Did you ever heard the method with filling it with water as a purge agent and maybe for cooling? Personally i don't go near a fuel/oil tank with a welder, i would blow through it, or blow up.

flush with hot water and dawn liquid . if you can't smell the fuel then its good to go. if you smell fuel do it again . i used high pressure steam at the power plant on my tank and it came out super clean

I've welded fuel tanks before, We always filled the tank with Smoke from a tail pipe do the tank had no oxygen inside of it. It works.

Glad you stressed a little air pressure. About 25 years ago when I had a paint shop for motorcycles, my buddy and I completely ruined a customer's laverda fuel tank by using too much air pressure, totally distorted it. Trying to find a replacement in the days before internet was a nightmare.

Wash with dawn soap and water, swish back and forth. Dump and rinse and you're done.

Next time consider using Aufhauser SilverAlloy 45% Ag BAg-5 Brazing Rods works great!

Have you ever considered using dry ice, to inert the tank? This method is use to demo large gas tanks (thousands of gallons capacity). Removal of the bracket, welding then reinstallation of the bracket, would be the ideal repair. As a point of information I am a retired safety professional and a retired certified high pressure MIG, TIG, stick welder.

Dry ice works well

For you to take on this job at all shows your confidence and expertise~! It took a bunch of Guts to fix this tank because you know this is somebodies "Baby" and will spread a bad word of mouth if it leaks again. I admire your courage~! New Sub because I want to see more of your Magic. 😲✌

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$160 seems pretty reasonable, it salvages most of what looks to be a very expensive paint job.

I would have likely taken the bracket off.

Would it have been better to cut the bracket loose, clean and weld again? Didn't look like it was a significant weld to start with. Almost looks like a crappy tack/stitch weld. If you had done it that way couldn't you have then Tig it? I'm guessing the customer didn't want to pay for it?

Remove the bracket, clean, repair "via TIG" and re-install bracket. 👍 At least TIG over the MIG weld for pen.

You have spare time?

I'm always worried about welding next to plastic tanks in cars 😬

Drop some dry ice in the tank. Dry ice evaporates turning into CO2 pushing all O2 out of the tank. No oxygen no boom.

Best thing for tanks is a chemical resistant resin liner . I realize this inst a resin liner video and its a welding video . Just thought I'd mention it

Empty the tank to be welded of any fuel connect the exhaust from your car for 5 or to 30 minutes depending on size of tank to weld leave the vehicle running while you weld braze, sodder, torch tank in half no problem. There is zero chance of explosion using this method. Works for gas, all types of fuel or oil no matter. After running auto exhaust from flexible hose fitting from tail pipe and fitting the other end into tank to be welded then to continue auto exhaust flowing through the tank and venting well out of the tank while welding repairs are being done. It is simply impossible to cause any fire or explosion. Truly the safest and best way to weld any type of gas or fuel tank.

The flashes gave me a migraine. Is there a way to make them less bright when videoing?

Only time I welded on a tank it was for a MR2 it was changing where the fuel pump is accessed to allow the owner to put in a second fuel pump. Since it was the highest point I ended up filling with water then purging the rest with argon. I figured with the size that was my best option even though it was cleaned out.

I knew a guy who used a cutting torch to remove the top from a barrel. I don't remember the name of the chemical that the barrel contained before it was emptied and in his possession. But someone will probably figure it out and I hope they comment below so others will be careful. His torch ignited the fumes only and the barrel exploded. He was blown up into tiny pieces and his wedding ring was stuck into a nearby brick wall. He was survived by his wife and newborn baby.

That's a petrooster.

Excellent! I was hired two different times because the guy before me blew themselves up, I've fixed many tanks but you must use common sense !

I had to cut out and patch a fairly large piece on my motorcycle tank. It took me forever to get all the leaks out (didn't really know what i was doing). I even painted it myself and it came out great, until it started leaking again. Now that I finally had all the leaks gone I decided to pressure test it like I should have before. So, I soaped it up and used what I had on hand to pressurize it - the exit of my shop vac. Now I have a very pretty bowed to hell unusable tank hanging on my wall; he's very right when he says to use a very small amount of pressure. I ended up finding a really nice matching set of panels and the tank on ebay that someone was trying to get rid of and that was that.

Is argon cheap?

yoyo have you heard about lazerwelding and is it a machine you think people should invest into our dosen it not even burn through properly?

a trick i like to use if i blow a hole is to fire up the gas plant and run the flame around the edge of the hole that was blown. the idea is to melt the metal creating a bead on the edge that is thicker than the base metal. being thicker it can take more heat and is less likely to run when you are trying to fill it. then you can weld up to that with the mig.

Nice job! In the past I would braze tanks instead of welding. I was too concerned that a mig would blow through, and then came along this video. Welp.. ya learned me somethin' today! Thanks Justin!

Very good solution. I would have done it the same way. Today I had to repair a broken snozzle from a fire truck. 3" aluminum pipe broken in two pieces. I like my carbide air grinder, it removes a lot of metal and leave the bevel clean and shiny.

Absolutely ridiculous. The customer is an idiot. That tank is going to have more issues down the road. It should have been replaced. And what's more, why was it cachingered in the first place.....

You are pushing .035 wire? I would consider .025" wire sir

HI THERE, BRING IN THIS BUSINESS FOR 40 PLUS YEARS, DO YOU ALWAYS QUOTE THE JOB, OR JUST TIME AN MATERIAL, WITH A NOT TO EXCEED PRICE??? THANKS,, THE OLD OWNERS OF MY CO, HAD A STRICT QUOTE ONLY!!!! WHY?? THEY THE LWERE MULE-HEADED!!!!!!!! TO SAY THE LEAST! TY, AGAIN!

This is not the case but when I need to repair a gas tank I am puting the tank on a wood fire and the heat of that fire it takes out every particle of the gas remaining in the walls of the gas tank. I consider to be the only secure way to repair the gas tank with a welder tool.

I've welded fuel tanks that have been thoroughly cleaned but I've also welded tanks with fuel in them. You have to not only purge the tank to remove oxygen but keep gas flowing all the time while welding. you can use argon but CO2 is cheaper. Both are heavier than air, so you need to have a way for gas to escape slowly out the top. I use a flow meter on the purge gas so I know that gas is flowing. It would be nice to have someone monitor the gas flow but so far no one has been willing to be close enough.

We had a guy at work last week blow his up and burn his chest pretty good, It had been sitting since last fall and had been washed out twice, still had residual fumes in it I suppose. He had the gas cap opening facing his chest when it went. Guy got lucky it only blew his shirt apart and melted a little skin.

a cheap and dirty way to purge the tank is simply fill it with water.. soapy water works well too.. then drain it out and let it dry a little ..good to go

Jesus Christ!!! NEVER EVER EVER LIGHT THE FUMES ON A TANK!!!! YOU SERIOUSLY COULD HAVE PUFFED THE TANK AND RUINED THE ENTIRE JOB. 🤦‍♂️ how do I know? 😅😬

Reading the comments makes me sad about people's listening comprehension. People keep posting questions that YOU ANSWERED IN THE VIDEO.

I've welded on used fuel tanks before. Old trick to get rid of any hydrocarbons, plumb a hose from vehicle exhaust gas and run for about 20 minutes,

Step one: Make sure gas tank is half full and under pressure. This ensures you get into heaven. God likes when you weld with gas nearby

Good Job Amigo!👍

I just drop some Dry ice into the tank aka C2O. This probably only works for steel tanks though. I don't weld no fancy metals. (Don't store it in the freezer, the cold will kill the compressor.)

Why not use silicin bronze mig? Ive mig brazed a shit ton of crappy thin metal over the years,with .023 then silicon bronze,just wondering Thx for all you teach us!Dry ice is also a cheap easy solution.

I have a steamer but never thought to use it this way. Most tank that come to me are rusted with pinhole after pinhole. I hate em.

I have a 2015 V-Star 1300 that has developed a leak in the tank. I paid a local shop $300 to fix it. They used J.B. Weld on it. I didn't even get it home before it started leaking again. Since we're heading into winter time here in Oregon, it's finally getting to a time of the year when I won't be able to ride it much, so I'll have time to pull the tank off and fix it myself (which I should have done from the start). I was thinking of soldering it rather than brazing it, but it might be worth it to buy a brazing kit and do that instead.

After washing, I simply pump low level air flow into the tank. If anything flammable is left in the tank, the air vapor mixture is so lean that the flammable burns at the source and does not create an explosive AFR. I braze these brackets.. Old school stuff.

The fastest way to de-fume I ever saw a mechanic carry out was when my Honda Civic tank got punctured by a sharp rock on a dirt road from a random rock fall. The tank got a big dent and a hole, 100 Km from the nearest fuel station, and fuel leaking out, So I grabbed a couple of sticks a jammed them in the hole to slow the leak down. When we got to a small town, found the local mechanic, he collected the fuel he drained out, then he put the exhaust of his diesel truck into the tank. The heat vaporises any remaining fuel and the fumes are oxygen free. After 10 minutes he bashed the dent out a bit, then welded it up in 3 minutes. Re-filled the tank with the collected fuel (after re-fitting to the car), and away we went, $50 repair. Never leaked, good repair.

Many owners of custom bike crack their tanks (especially the older style split HD tanks) by failure to shim the mount brackets which causes the attachment bolts to bend then eventually cracking the tab or the tank. If you work on the bike as a whole not just the tank, make SURE you test fit the tank to the motorcycle, preferably before painting it. Then you won't get blamed for a crack because there won't be one. USB borescopes are dirt cheap and dandy for inspecting fuel and oil tanks and inside frame tubes.

@ Limpy 817 should have watched this vid,he torched himself pretty good doing this job incorrectly,his tank go boom.