BOOM! How can i safely weld fuel tank? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

fishuntr · 06-12-2002, 10:06 PM

I need to move the fill pipes on two saddle tanks. Task involves cutting new holes with holesaw, welding in new fill pipes, cutting off and welding a cap on old fill locations. When i was a kid we used to fill them with soapy water. For several reasons, (aside from being old & wise), this wont work. Tanks have not had any fuel in them in many years and are bone dry, but still have faint odor of gasoline.

I am competent to do the job, just don't want to blow myself up in the process. Is there a safe way to do this?

Thanks

nu2-72 · 06-12-2002, 10:20 PM

If there is still a faint smell of fuel, I would #1 remove tank to an outdoor location. #2 Use a shop vac to blow air into the tank and purge it of all fumes. ( do not vac fumes out as you do not want fumes in the vac canister where sparks may occur during startup) #3 you can then purge the tank with a non flammable gas like nitrogen or CO2. If you are wire welding, filling the tank with CO2/argon mix is welding gas anyway. Use low pressure so as not to effect the weld, just keep the tank clear. #4 ask more people, this is my experience and more input is always better. Good luck.

fishuntr · 06-12-2002, 10:33 PM

That's a good point about an inert gas displacing the oxygen. I will be doing the job with a MIG welder. I use a CO2 tank for my onboard air supply in my 4wheeler. Would this gas work?

*Gee_Emm* · 06-12-2002, 11:34 PM

Why doensnt the trick to fill it with water work?

Mike C · 06-12-2002, 11:45 PM

Hook up a blower nozzle to your air compressor and leave it blowing into and circulating while working on the tank and it keeps gas pockets from forming. It IS a risky job, however. Take it to a radiator shop and have it steam cleaned/boiled whatever they call it and then you should be able to work on it fine. Just use the circulating air while working at it.

Alexis · 06-12-2002, 11:48 PM

throw a match in the tank(while lit), just a thought

*Zkast* · 06-12-2002, 11:54 PM

im curious too... why wouldnt filling it with water work for you? I've patched a few using this method and it seems to work quite well. All the water is doing is filling the area with non flammable liquid instead of flammable gas vapor. Once your done grab some denatured alcohol, slosh it around a bit and blow with compressed air.

72 custom C-20 · 06-12-2002, 11:56 PM

two words " Dry Ice "
They used to use that stuf to drop in large steel 100,000 gal fuel tanks and then cut them open to clean them out. then lift them out of the ground and cut them up.

Got that story from my ex-girls father. He's still alive too! It supposedly "raises the flash point" in his words.

Don't know if they still use that technique. It's co2 right.

David

Stano · 06-12-2002, 11:56 PM

At the body shop I work at we have to repair motor cycle gas tanks quite often and we usually drain them let them sit out for a day or so and then fill them with water and proceed to weld or use the stud gun on them with no problem. I worked with a guy that has customized harleys for the better part of his life and he did it the same way. If this scares you then don't do it but if the tanks were gonna blow I think they would have in the 40 or so I've seen and worked on my self.

**StingRay** · 06-13-2002, 01:46 AM

A buddy of mine has a rad shop and repairs tanks all of the time. He drains the fuel, rinses with water and then attaches a vacuum cleaner hose to the vacuum outlet so that it blows warm air into the tank for a few hours. You could rinse with water again for good measure if you wanted to. After all of that there wouldn't be anything left that could combust.

Maximum Overdrive · 06-13-2002, 07:54 AM

I agree with the dry ice thing. Around here most stations are trying to meet the mandate to upgrade their tanks and they are using dry ice when they cut them up. I believe the theory behind it is as the ice melts it turns directly into a gas and this gas is heavier then the air and gas vapors thus pushing them out and filling the space only with the gas from the ice.

tom hand · 06-13-2002, 08:13 AM

The only problem with this thread is the people that did it the wrong way don't get to reply. I worked in a shop that employed 6 full time welders and none of them would go near a gas tank without pumping CO2 in it. I can see where the dry ice thing would work because it is nothing but CO2. The main thing is if you have ANY doubt, take it to a pro because you don't get a second chance. And remember an empty gas tank is ten times more dangerous than a full one.

71GMC_3/4T · 06-13-2002, 10:26 AM

"The only problem with this thread is the people that did it the wrong way don't get to reply. " <-- Tom Hand

Ah, good point Tom! LOL on that one, even though it isn't funny.
My shop teacher way back in HS told us the military used to pump exhaust from a running diesel into the tank for a while before welding it. I like the dry ice idea myself. But like Tom says, take it to a shop! Otherwise fishuntr, we have to wait for your next post and worry about you...

JimKshortstep4x4 · 06-13-2002, 10:51 AM

Having the tank cleaned out at a radiator shop is probably the safest way to go. Years ago, I tried the water in the tank trick and I let it run through and overflow so that the tank was completely filled with water. When I started to solder the tank with a torch, it woofed at me and since then I have had them cleaned.

Gasoline is pretty scary and a little bit has lots of energy in it.

Jim

**Desert Rat** · 06-13-2002, 11:54 AM

Rat advice take it elsewheres,be better to pay $40 and watch someone else blow up than yourself.

jku72 · 06-13-2002, 12:50 PM

I have safly welded gas tanks by filling them with water. This is apparently an accepted practice. All the guys I know do it that way, and it is easy. This is what I was taught years ago at my welding certification class, well, 10 years ago. Maybe the laws changed, but i still do it this way.

fishuntr · 06-13-2002, 03:08 PM

Thanks for all the replies. I didn't completely describe the job. The reason i can't use water is that i also have to cut out the two tubes that the mounting bolts go through. The bolts have been impossible to get out; so, i was going to just cut the tubes out and replace them at the same time.

I will probably have them thoroughly boiled out, then use the CO2 from my fill bottle. I can regulate it down to a slow flow and do the job. I wont take too many chances; didn't get to 60 by doing stupid things (well maybe i was lucky some of the time:p )
If i could afford it i would probably have it professionally done.

On the other hand, that would defeat my argument to my spouse that by having my own MIG, TIG and Plasma Cutter, i could do my own work. I really have done a lot of welding, but this is a little different than roll cages, hitches, racks and such.
Thanks for all the suggestions. Jimmy

colohusker · 06-13-2002, 05:10 PM

Good luck! I guess if you don't let us know how it went, we'll know it didn't go well! the CO2 from the welder should work fine, just make sure to give it plenty of time to fill the tanks before you start in.

06-12-2002, 11:45 PM	#5
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,715	Hook up a blower nozzle to your air compressor and leave it blowing into and circulating while working on the tank and it keeps gas pockets from forming. It IS a risky job, however. Take it to a radiator shop and have it steam cleaned/boiled whatever they call it and then you should be able to work on it fine. Just use the circulating air while working at it. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

06-12-2002, 11:56 PM	#8
72 custom C-20 Registered User Join Date: May 2002 Location: Southampton, Pa. Posts: 27	two words " Dry Ice " They used to use that stuf to drop in large steel 100,000 gal fuel tanks and then cut them open to clean them out. then lift them out of the ground and cut them up. Got that story from my ex-girls father. He's still alive too! It supposedly "raises the flash point" in his words. Don't know if they still use that technique. It's co2 right. David __________________ 72 C-20 custom/deluxe med. blue 350 64 oldsmobile F-85 deluxe 330ci. 86 KX 125 Old school, mint Southampton, Pa.

06-13-2002, 01:46 AM	#10
StingRay Senior Member Join Date: Mar 2000 Location: Saskatoon,SK,Canada Posts: 2,476	A buddy of mine has a rad shop and repairs tanks all of the time. He drains the fuel, rinses with water and then attaches a vacuum cleaner hose to the vacuum outlet so that it blows warm air into the tank for a few hours. You could rinse with water again for good measure if you wanted to. After all of that there wouldn't be anything left that could combust. __________________ Saskatoon, Saskatchewan Canada

06-13-2002, 07:54 AM	#11
Maximum Overdrive December 21, 2012 Join Date: Apr 2000 Location: Black Eagle, Montana Posts: 1,634	I agree with the dry ice thing. Around here most stations are trying to meet the mandate to upgrade their tanks and they are using dry ice when they cut them up. I believe the theory behind it is as the ice melts it turns directly into a gas and this gas is heavier then the air and gas vapors thus pushing them out and filling the space only with the gas from the ice. __________________ *"!Ama Sua, Ama Kjella, Ama Lllulla!"*

06-13-2002, 08:13 AM	#12
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	The only problem with this thread is the people that did it the wrong way don't get to reply. I worked in a shop that employed 6 full time welders and none of them would go near a gas tank without pumping CO2 in it. I can see where the dry ice thing would work because it is nothing but CO2. The main thing is if you have ANY doubt, take it to a pro because you don't get a second chance. And remember an empty gas tank is ten times more dangerous than a full one. __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS Last edited by tom hand; 06-13-2002 at 10:45 AM.

06-12-2002, 10:06 PM	#1
fishuntr Registered User Join Date: Jul 2000 Location: Lucerne Valley, CA., USA Posts: 50	BOOM! How can i safely weld fuel tank? I need to move the fill pipes on two saddle tanks. Task involves cutting new holes with holesaw, welding in new fill pipes, cutting off and welding a cap on old fill locations. When i was a kid we used to fill them with soapy water. For several reasons, (aside from being old & wise), this wont work. Tanks have not had any fuel in them in many years and are bone dry, but still have faint odor of gasoline. I am competent to do the job, just don't want to blow myself up in the process. Is there a safe way to do this? Thanks __________________ 72 C-20,LB,350, 4spd, 1 owner

06-12-2002, 10:20 PM	#2
nu2-72 Senior Member Join Date: Apr 2001 Location: Amazonia, Mo. USA Posts: 2,821	If there is still a faint smell of fuel, I would #1 remove tank to an outdoor location. #2 Use a shop vac to blow air into the tank and purge it of all fumes. ( do not vac fumes out as you do not want fumes in the vac canister where sparks may occur during startup) #3 you can then purge the tank with a non flammable gas like nitrogen or CO2. If you are wire welding, filling the tank with CO2/argon mix is welding gas anyway. Use low pressure so as not to effect the weld, just keep the tank clear. #4 ask more people, this is my experience and more input is always better. Good luck. __________________ 72 3/4 4x4 350 4spd 72 3/4 4x4 350 auto 2004 Duramax Silverado 4x4 2006 Duramax Crew cab 4x4 2010 Harley Ultra Limited 2011 Harley Street Glide

06-12-2002, 10:33 PM	#3
fishuntr Registered User Join Date: Jul 2000 Location: Lucerne Valley, CA., USA Posts: 50	Re:CO2 That's a good point about an inert gas displacing the oxygen. I will be doing the job with a MIG welder. I use a CO2 tank for my onboard air supply in my 4wheeler. Would this gas work? __________________ 72 C-20,LB,350, 4spd, 1 owner

06-12-2002, 11:34 PM	#4
Gee_Emm Account Suspended Join Date: Sep 2000 Posts: 4,002	Why doensnt the trick to fill it with water work?

06-12-2002, 11:48 PM	#6
Alexis Member since 2000 Join Date: Dec 2000 Location: Mountain View Ca / Mexico Posts: 7,879	throw a match in the tank(while lit), just a thought

06-12-2002, 11:54 PM	#7
Zkast Account Suspended Join Date: May 2002 Location: Olathe, Kansas Posts: 929	im curious too... why wouldnt filling it with water work for you? I've patched a few using this method and it seems to work quite well. All the water is doing is filling the area with non flammable liquid instead of flammable gas vapor. Once your done grab some denatured alcohol, slosh it around a bit and blow with compressed air.

06-12-2002, 11:56 PM	#9
Stano Registered User Join Date: Jul 2000 Location: Mo Posts: 963	At the body shop I work at we have to repair motor cycle gas tanks quite often and we usually drain them let them sit out for a day or so and then fill them with water and proceed to weld or use the stud gun on them with no problem. I worked with a guy that has customized harleys for the better part of his life and he did it the same way. If this scares you then don't do it but if the tanks were gonna blow I think they would have in the 40 or so I've seen and worked on my self.

06-13-2002, 10:26 AM	#13
71GMC_3/4T Weapons Of Construction Join Date: Apr 2000 Location: Colorado, USA Posts: 1,095	"The only problem with this thread is the people that did it the wrong way don't get to reply. " <-- Tom Hand Ah, good point Tom! LOL on that one, even though it isn't funny. My shop teacher way back in HS told us the military used to pump exhaust from a running diesel into the tank for a while before welding it. I like the dry ice idea myself. But like Tom says, take it to a shop! Otherwise fishuntr, we have to wait for your next post and worry about you... __________________ 1971 GMC 2500, 402/TH400 4.10 Daily Driver Lafayette, CO

06-13-2002, 10:51 AM	#14
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Having the tank cleaned out at a radiator shop is probably the safest way to go. Years ago, I tried the water in the tank trick and I let it run through and overflow so that the tank was completely filled with water. When I started to solder the tank with a torch, it woofed at me and since then I have had them cleaned. Gasoline is pretty scary and a little bit has lots of energy in it. Jim

06-13-2002, 11:54 AM	#15
Desert Rat Senior Member Join Date: Dec 1999 Location: Darrington, Washington Posts: 3,963	Rat advice take it elsewheres,be better to pay $40 and watch someone else blow up than yourself.



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06-13-2002, 12:50 PM	#16
jku72 Registered User Join Date: Jan 2002 Location: cornville, maine Posts: 659	I have safly welded gas tanks by filling them with water. This is apparently an accepted practice. All the guys I know do it that way, and it is easy. This is what I was taught years ago at my welding certification class, well, 10 years ago. Maybe the laws changed, but i still do it this way. __________________ jku Cornville, Maine 68 C10 burb 42 Willys MB 46 Dodge WF-32 1.5 ton 53 & 56 Olds' 60 Cadillac 22 Dodge Brothers

06-13-2002, 03:08 PM	#17
fishuntr Registered User Join Date: Jul 2000 Location: Lucerne Valley, CA., USA Posts: 50	More info re tank welding Thanks for all the replies. I didn't completely describe the job. The reason i can't use water is that i also have to cut out the two tubes that the mounting bolts go through. The bolts have been impossible to get out; so, i was going to just cut the tubes out and replace them at the same time. I will probably have them thoroughly boiled out, then use the CO2 from my fill bottle. I can regulate it down to a slow flow and do the job. I wont take too many chances; didn't get to 60 by doing stupid things (well maybe i was lucky some of the time:p ) If i could afford it i would probably have it professionally done. On the other hand, that would defeat my argument to my spouse that by having my own MIG, TIG and Plasma Cutter, i could do my own work. I really have done a lot of welding, but this is a little different than roll cages, hitches, racks and such. Thanks for all the suggestions. Jimmy __________________ 72 C-20,LB,350, 4spd, 1 owner

06-13-2002, 05:10 PM	#18
colohusker Registered User Join Date: Apr 2002 Location: Longmont, CO Posts: 436	Good luck! I guess if you don't let us know how it went, we'll know it didn't go well! the CO2 from the welder should work fine, just make sure to give it plenty of time to fill the tanks before you start in. __________________ ------------------------------------------------ I say it's only money, my wife says it's only a truck.... '71 C10 Deluxe, factory ac, ps, pb, should be done by 2102 Longmont, CO husker95@hotmail.com

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