welding a gas tank

[joehalford01]

Here is a dangerous topic that has been brought up several times on other forums. When I went camping with my brother in law this weekend we got on the subject somehow. He is a heavy equipment welder and they weld gas tanks fairly frequently. But first, a disclaimer: If you blow yourself up, it is your own fault, be super duper careful!

He said that if they need to make a repair to a gas tank they usually drain it and let it air out for a few days. Then fill it with water and let it sit for a bit, then drain and let it air out again. The main issue is making sure there are no fumes. If they are welding something like tabs on the tank or something other then a leak, they usually fill it with water while they weld on it. Also; if it is a leak they are fixing, after doing all of the above, before sticking their face down there to weld it up, they will take the welding rod and tap it against the inside of the tank while looking away. The rationale being that it's better to set the fumes off with your face away from the explosion.

I have not tried this personally but if someone is considering a gas tank repair, then i thought it might help. Also; please don't flame me over the inherent danger in that last bit. It is very dangerous, and you should not weld a tank at all unless you are very certain the fumes are gone. Sparking on the inside is a final test before you weld it. (on a final note, my brother in law also mentioned, when tanks come in for welding he quickly finds something else to do so he dosn't have to weld on it )

 

[Gastrick]

When I weld a gas tank I conduct the operation pretty much as Joe has described. After draining the tank, I flush it with water several times. I usually turn on a hose and insert it into the bung or fill tube and just let the water run for a while and flush the tank out. It's the fumes that will ignite. I have never had an explosive incident result from welding a gas tank. I have caught myself on fire, but that's a different story and had nothing to do with welding a gas tank.

Wait till Don sees this and tells about the guy that welds the tanks when they are full of gasoline

 

[joehalford01]

ok, so how did u catch yourself on fire?

 

[WIZEGUY]

ok, so how did u catch yourself on fire?

Well, judging by his photo collection, his flash caught his hair on fire.....

 

[Gastrick]

Ahhh, never any slack from the wisecat .

Actually, MIG welding sparks caught a shop towell that was right behind me covering some shiny suspension parts on fire, which in turn caught the back of my pants and shirt on fire. I was welding a chassis, not a gas tank when this happened. I have since purchased a welding blanket for such tasks.

 

[Bonehead]

You guys are right on the money about fumes. On big tanks, (3000 gallon), I have used steam to take the place of the vapors. I have used Carbon Monoxide from exhaust for the same task.

I used to cap off natural gas wells that where no longer producing too well. To pull the casing, (pipe) before they where plugged, I had to weld on to the pipe that carries the gas. Before you dress it with a grinder, you always use the torch to ignite the gas built up inside the pipe. It's that crouch down and look away and stick the torch over the hole. Sometimes just a pop, sometimes flames 30 feet in the air, always fun.

A friend of mine once blew him self up, cutting up old barrels. He had cut up several that where supposed to have had soap in them. Then sat his torch tip down to cut another barrel, and boom. He never even cut through. the heat ignighted the fumes and split the seam open on the barrel. The explosion raised the barrel up with such force it bent the torch head back about 4 inches and broke his wrist. When he woke up. He had a huge knot on the back of his head where he hit the ground. The force blacked both eyes.

I guess now we know what happens if you mess it up.

 

[35Mastr]

Thats a mistake I hope I never make.Fumes are serious stuff and will kill you if not careful.

 

[DaJoker]

When I welded a new bung in my gas tank for the Sporty, I used CO2 to purge. I have a friend who is a welder for the Navy, and he recommended CO2 since it's heavier than air, it just fills the tank without any special tools. Just stick the hose in and "fill" the tank for a few minutes. I just happened to have a tank on my kegerator in the basement, and the CO2 worked pretty well. I did let the tank air out in the shed for about a week first as well though.

 

[babyface]

Burned hands

I've burned my hands & mustache more than once fooling with gas tanks. Nothing like the smell of singed mustache in the morning! I really like the CO2 trick though.

 

[Hotroddaddy]

I was talking with a guy the other night , who works for a propane comany, he says they take a pipe about 50 feet long then it kicks up about 6-7 feet, they attach it to the tank ,then light the pipe to burn off all the fumes, some how it will not backlight into the tank.

 

[52 HenryJ]

When we fix 10,000 gal fuel tanks we inert the fumes with dry ice, average of 100 pounds for 10,000 gal and seal off the tank but a 1/8 " vent hole for fume evacuation.keep in mind these are steel industrial tanks used in the petroleum industry. never tried it on a car gas tank but might work.

 

[roosters_rat_rods]

i was an army engineer for 6 yrs..i repaired more fuel tanks than a care to remember...we use lots of exhaust fumes,carbon monoxide..and a prayer...lol.im still here though.....we did use a lot of lead too....rooster

 

[Gastrick]

Rooster, do you glow in the dark?

 

[roosters_rat_rods]

Rooster, do you glow in the dark?

no lowing here but make me wonder..i can't hear to well any more,i spent 3 yrs int he field artillery shooting the big guns....ear plugs helped,but did'nt always have enough time to put them in before firring mission..but would'nt tade it for anything..feels great to be a veteran.....rooster