Welding a gas barrel safety question?

UNCLEBUCK · February 21, 2005, 12:46:21 AM

I have heard that car exhaust piped into a gas barrel will make it safe for welding and I am going to be doing this as soon as I hear the do"s and dont"s from anyone that has experience at this. Thanks

Fla._Deadheader · February 21, 2005, 07:12:22 AM

UncleBuck, here's my experience with gas tanks. What happens is, the liquid, over time, soaks into the pores of the metal. When you apply heat, it releases the FUMES. THAT is the dangerous stuff. Liquid will BURN, FUMES blow.

I have made repairs 2 ways. Fill the tank to the tippytop, if possible, to eliminate fumes. If you can get the leaky part to not leak, by placing it toward the top, then you can weld. All you get is a little external fire, that can be smothered. Also, you CAN run a hose from a vehicle exhaust to the tank and let it fill with spent fumes. That however, will not be as safe. The spent fumes may still contain SOME unspent gas vapors, unless you use Diesel exhaust.

Why weld the tank??? The epoxy repair kit for gas tanks work very well, IF you get the tank real clean so it will stick.

PLEASE BE CAREFUL, WE ALL LIKE YOU HERE

sawguy21 · February 21, 2005, 08:41:04 AM

Right on, Harold, I would never trust car exhaust fumes to purge a tank. At a former job, we had the fuel trailers purged with steam before repairs were attempted. Uncle Buck, if you screw up doing this it will only happen once :D

Quartlow · February 21, 2005, 12:37:13 PM

I watched a guy (from a great distance :D ) do this once only he used diesel fumes from his pickup truck. Persoanly I'm all for the epoxy route

I have welded leaking fuel tanks on heavy equipment . But A. that was adiesel, and B it was heavy steel like 1/4 inch or so. Funny it still cleared out the shop

johnjbc · February 21, 2005, 01:33:11 PM

Would seem to me that using diesel wouldn't be a good idea. Diesel engines don't have a throttle plate. At idle you are still pumping a full cylinder of air and injecting just a small amount of fuel leaving most of the oxygen unburned :

. A gas engine unless you have a bad plug or something, should be burning most of the oxygen. I have a farm tank that need a drain wielded in place but haven't got my nerve up to do it yet. Thought about putting the shop vac exhaust in and letting it run for a hour or so. BUT?

Ianab · February 21, 2005, 03:22:38 PM

John
Dont try the shop vac, whatever you use has to displace all the oxygen from the tank so it cant react with the fuel residue that will be released from the metal AS YOU WELD. The welders on the petrochemical plants usually purge vessels / pipes with nitrogen to force out the air. Nitrogen + gas fumes + spark = no reaction.
As most home workshops dont have nitrogen on tap, some other way to displace the oxygen is needed.
Water will be the safest, once the tank is full of water you know there is no free oxygen in there. Petrol exhaust fumes should also contain practically no oxygen (Mostly Nitrogen, CO2 and water vapour - all pretty inert ) A little bit of unburnt fuel vapour wont hurt so long as there is not enough O2 for ignition.

Diesel exhaust is probably not a good idea, at idle most of the oxygen passes straight thru. You cant kill yourself by sitting in the shed with an idling diesel, you will make yourself horribly sick and have to go and throw up before it seriously affects you.

BE CAREFULL OUT THERE.

As an expriment at school we did the tin can with 2 or 3 drops of petrol in it, bang the lid on tight and poke a match in a small hole in the side. BANG, lid hits the ceiling. Scale that 1/2 litre tin up 100 times, and BANG, you hit the ceiling

Ian

Dangerous_Dan · February 21, 2005, 04:27:20 PM

Don't use the shop vac. If it's gasoline or something highly volitile the sparks from the brush motor will set off the fumes your removing. Your shopvac will become a bomb and in turn ignite your tank making another unwanted boom.
I have used the water trick, filling it all the way to the top. You will need to put the area you are welding up so you have a small amount of air below where you are making the weld. If water is directly on the back side of the weld area it's harder to stop a leak and get a good weld. All I can say is be carefull. I have also taken a CO2 fire extinguisher and flooded the inside of the tank so no oxygen is present but I get nervious when welding a tank this way. The water is the safest although its more work.
What is it that you are welding and what is the flammable liquid?
I like welding over epoxy, although it does work very well.

rebocardo · February 21, 2005, 05:07:58 PM

Back when we were young, stupid, and poor we brazed gas tanks filled to the top with water. But, even with that accidents still happen because you can not eliminate the gas and fumes completely from the inner and outer shell of the gas tank.

Sometimes what happens is the gas will film on top of the water, evaporate while you are welding and BOOM. The safest way is to rinse the inside of the tank with dish soap, though there is always a small risk and considering an evaporated teaspoon of gas is equal to a stick of dynamite in energy it does not take much to soil your pants, blind, maim, or kill you.

What I might do if I was going to weld a gas barrel is rinse the barrel out with soap and water. Then burn a wood fire in it for an hour and then rinse the barrel out again. It should pretty much burn all the paint and residue off the inside and outside of the barrel.

bberry · February 21, 2005, 06:59:31 PM

We used to cut and weld propane tanks to make culverts. We would remove the valve and fill with water. Let set for a day then you would see a film on top of the water. That would burn. Then siphon of a few inches of water and touch it off and get a small pop. Siphon off a couple more inches and repeat until down to flat and then cut off end. Leave filled with water for few days and then dump and cut off other end. I have welded and brazed propane and gas tanks this way numerous times. Detergent in the water is helpful. The old timers would solder gas tanks(even had gas in them) with an iron so no flame could cause an explosion. Works good.
Epoxy on the outside and internal coating is a safer way to go. Stops future rust on inside also. If you decide on welding using flame keep your head to one side of tank. They tend to blow straight up.

Weekend_Sawyer · February 21, 2005, 07:12:41 PM

My Father was a welder, he would weld a gas tank by first filling it with oxygen, yep, he said pure oxy would not burn, i wached him do it once... from around a corner, seemed to work fine. I would not do it, I would get a good used one from a junk yard.

We used to use this stuff called Slosh and Seal inside gas tanks, pour it in, slosh it around and dump it out. That worked real well.

Jon

UNCLEBUCK · February 21, 2005, 07:57:28 PM

Wow I am glad I asked . I bought outdoor wood boiler plans on ebay and there are 3 different models to choose . A big pallet burner sized, a medium sized and a beginners model made from fuel barrels . Here is just a looksy at one page of the basic model. Very nice plans,alot of step by step photos and details from beginning to end except how to prevent "BOOM" . I guess I better buy new/unused barrels so the reason I asked is because I got these barrels on the farm . The smaller barrel slips inside the front of the bigger barrel and the firebox door gets torched out of the front of the smaller barrel leaving no lower lip on the firebox door so I can burn wood/garbage and clean out the melted bottle caps and glass with a garden hoe and be a good janitor. ;D I thought there was a sure way to get gas fumes out but I dont like "BOOM" . Thank you everyone for all the tips and advice but I think I will buy unused barrels . Copenhagen wont kill me but "BOOM" I think would finish me off for sure ! My picture of plan is slow to upload so I will show the plan a bit later. The more I think about this I could put about 20 gallons of sawdust in each barrel and place them over a small wood pile and light the pile and run and let them burn and boom all day and night . I have to think about this because new barrels I bet are expensive

UNCLEBUCK · February 21, 2005, 08:21:45 PM

Here is 1 picture drawing from plans of the beginners boiler , its the only one that is round , the other two bigger models are made from sheet steel like 4x4 and 4x6 fireboxes. This small wood boiler sounds simple so I will re-read everyones input several times . Thanks again for all the replies !

Fla._Deadheader · February 21, 2005, 08:24:14 PM

If ya got a brush pile, open the bungs on the barrels and put 'em in the brush pile. Light the brush and them barrels will just burn like torches. Ya get in trouble when there is NO opening for the fire to get out.

I have burned several Propane tanks out that way. No real danger that way. ;) ;D ;D ;D This is for real information. No joking, here. ;D ;D

UNCLEBUCK · February 21, 2005, 08:27:47 PM

If I stay away from barrels that have had gas in them can I be safe by using barrels that I drained diesel fuel out of and go ahead and weld away on them ? This might be the way to go?

Wudman · February 21, 2005, 08:29:36 PM

For safety, fill that tank full of water before welding or cutting. We lost a neighbor some years ago to a hatch being blown off of a tar kettle. He ran a small residential paving business. The hatch on the kettle was stuck shut with solidified tar around the rim. He took a torch to soften the tar. The torch set off an explosion in the kettle and blew the hatch off......he was leaning across the hatch at the time and was struck and killed. The hatch went on up through the roof of the shop and limbed up a large white oak. It came to rest over 300 feet from the shop. Any type of petrol and fire don't mix well.

Wudman

UNCLEBUCK · February 21, 2005, 08:34:37 PM

Brush piles ! Oh yeah I knew I could count on you all ! Thanks F.D. . Now I am going to do that , I will take pictures from far away when they start to shoot flames . Thanks many many times ! Sorry to hear that Wudman I know this was a dangerous idea but I feel good about this brush pile method and I feel safe after all the brush has burned . Now I will have fun making my wood boiler knowing it was free and you guys made it free by all your answers ! 10-4 8)

Rockn H · February 21, 2005, 10:16:05 PM

Uncle Buck

From the plans it looks like a heating oil tank or diesel tank. If that is the case the chance of an actual explosion from an open flame is much less.

WH_Conley · February 21, 2005, 10:24:01 PM

Kinda off topic, but isn't a fuel oil tank kinda thin for a stove, seems like a lot of work for a relatively short life span. Course I'm prone to overbuilding.

UNCLEBUCK · February 21, 2005, 10:46:16 PM

WH , yes it is thin for a boiler but the weld can be ground off around the firebox and slide in another newer barrel from the brush pile . From all my looking at wood boilers I see that being able to scrape the back of the firebox every couple days prevents the creosut build up which makes it last longer. I have looked at boilers that were not stainless steel that were still chugging after 15 years becasue of the simple fact that the firebox was able to get a good scraping out with a garden hoe . Alot of boilers I looked at had ash augers but I think that would be hard to crank if I also burn garbage due to half melted cans and glass . With little money invested it will be fun to see how it holds up. The other 2 plans are 1/4" cold rolled sheet steel but I better wait with those . I wish I could show all the color photos of these boilers but I think it would get me in some kind of copyright troubles with the man selling the plans on ebay .

Dangerous_Dan · February 21, 2005, 11:27:14 PM

Ok
Now I know what you're up to.
Before I set up the retromiser to heat my shop I wanted to make my own boiler. What I figured would be easy to build, heavy duty and cheap is to start with a large horizontal air compressor tank. Get another compressor tank that is a little smaller in diameter. Cut the head on the big tank so the little tank slips inside. The little tank will need some patching/plugging/grinding where any bungs may be protruding outward. (don't laugh :D a bung is the threaded flange that welds to the tank) I think some flat stock welded into the large tank that would support the smaller tank when it is slid in would make assembly for welding easier. These supports could be set up as baffles to direct the water around the fire evenly. Once the 2 tanks are nested together you need to make a good weld where they come together. Take the circle that was cut out of the big tank and use it as the door. Use the existing bungs on the outer tank for the water connections. A chimney will need to be installed through both tanks. I figured I could drill a small hole straight down through both tanks where the chimney should go and open it up to a 8" or so circle with a torch and a piece of wire as a guide. Find some 8" or so pipe with similar wall thickness as the tanks, drop it through both tanks and weld it up.
I havn't built it except for in my head :

but I think it might work.
Around here compressor tanks are cheap and a lot tuffer than a drum.
Whadayathink ???

Furby · February 22, 2005, 12:05:59 AM

I'm reading all this and wondering how to cut the end off a large propane tank.
The ones I'm talking about have the bung in the middle of the tank.
Water would be best/easiest I see from reading this, but I'm talking about cutting the end clean off, not welding a leak.
The water level will drop as you cut the end from the top, is that ok?
The only other way I can see, would be to fill the tank, cap the bung, and use heavy equipment to stand the tank on end.
Waaaay to much work.

WH_Conley · February 22, 2005, 12:09:53 AM

Unclebuck, if yer gonna burn those barrells first prime and paint will help retard rust. I know, yer gonna burn em again, but this time they will have water opposite the fire. outside will rust pretty quick if not protected. got a buddy worked on boilers alot, he looked at my water stove and gave me this pointer, suggested Imron paint, due to temperature, that was a few years back may be something better now.

DD, thicker is better, I been thinking of building a bigger stove, basically what you are saying but adding an external tank, maybe an old bulk milk tank that is insulated should be cheap as many dairies went under, larger resevor, heat water in stove, move it to holding tank, pull heating water from reserve tank, basically two interdependent systems.

now, if you understand that I must be better at explanin than I thought :D

Rockn H · February 22, 2005, 12:12:56 AM

I've built several double barrel stoves,two 50 gallon drums on top of each other, for friends. One heats his 40 by 60 shop with his. The trick to keep the bottom from burning out is an inch or two of sand even dirt as long as there is no rocks that may pop.

WH_Conley · February 22, 2005, 12:19:03 AM

Problem with water stove is not burn out but rust out.

Fla._Deadheader · February 22, 2005, 05:58:50 AM

Furby, Same as UncleBuck. Brush pile. You are more sweating the vapors from the steel, than actually burning the tank itself. Do NOT make a huge fire to do this. BE SURE to have open holes in the tank before starting.