Thread: Welding around diesel tanks

It seems a local cane cocky was badly burned when he performed welding on his tractor.As many others have done he assumed he was OK as diesel has a low volatility.
Apparently the diesel was heated somehow under pressure.
and a explosion and fire followed.
Sound familiar.That's how diesel engines work.

The man had to be taken to Brisbane ,so its not sounding good.


We need to check every time.
Take me for instance, I used thinners to clean dirty alloy for welding- forgot to return the can to the paint locker for such things. I was lucky this time.

Take care friends.
Check your working area for flammables

Grahame

Grahame, many years ago now I did a medivac on a guy who was welding on a 44gal drum full of petrol (about 1/2 to 3/4 full). 99% third degree burns, obviously he didn't make it.

Having seen it first hand I can say you do not want to go that way. Take any other route, it ain't nice and it ain't pretty.

Thanks for the reminder.

Diesel itself dosen't burn its the fumes it gives off that burn, ignight and explode.
Diesel starts to produce fumes at 100 deg C , so welding on any fuel tank is dangerous
Many think that washing out the tank or drum once or twice with water makes it safe to oxy cut or weld but the small ammounts of fuel left is enough to evaporate under heat to create an explosive atmosphere within the tank and BOOM your dead.
Diesel is no safer than petrol just takes more heat but can produce the same energy.

Rgds

I saw some CIG guys weld a fuel tank at a race meeting a long time ago. They emptied as much fuel as possible out of it, gave the tank a rinse with water and then filled it with CO2 or similar. I stood back the appropriate distance but they didn't have any qualms about it. I might have seen it, but I still wouldn't do it.

i have heard that its better for the tank to be full than to drain off any diesel or empty, I have seen automotive petrol tanks explode and would definately leave them alone.

G’Day Graeme,
Back in 1984 I had to weld a petrol tank on my Landcruiser. (Petrol is a whole lot more volatile than diesel)… so I really thought about it before committing to the job. Not wanting to disappear in a big flash . I came up with the idea of using dry ice. You drain off the fuel and put in a kilo or so of dry ice and then wait until the vapour comes out of the highest outlet and you’re ready to weld. The dry ice evaporates into CO2 (flame retardant) and also displaces any residue vapour. The cooling effect of the ice chills any liquid residue that may still be present and prevents it from vapourising.. When you’ve finished you just pour fuel back into the tank melting the dry ice into CO2 and leaving no water to contaminate the fuel. The dry ice is pretty easy to get and can be ordered from any BOC depot.
I sent the idea to a few places after I’d proved it and I was told that Australian Standards where going to adopt it… I don’t know if that ever happened, but I I’ve used the method a few times since and it works very well.
Cheers, Steve.

Nothing like resurrecting an old thread.

My vintage motoX bike has come up with a crack in the fuel tank (Obviously not Diesel, but it's a similar topic), and I was wondering about how to go welding it up without too much unnecessary explosion related death.

I've heard you can inert it with Argon, or CO2, (As well as some other theories such as filling the tank with water, which sounds a bit bodgy to me)

How's the right way to go about it?

I see supporting claims for Dry Ice above there from Grryphon, but I'm understandably nervous about losing my arms and having half a petrol tank launched through my face, so a few more back-up claims can't hurt.

During my younger days I used to go out the back of Bourke shooting. The guys who lived on the farm out there were a wealth of knowledge to us city slickers. They could fix anything with little if any special gear.

They used to start up one of the cars and put a pipe from the exhaust into the empty fuel tank and ran the motor while welding it with the Oxy.

They also told of a Model "A" Ford fuel tank which had been left out in the paddock for over 30 years empty which exploded when a neighbouring farmer tried to weld it, seems traces of fuel were still in the seams of the tank. ???????

The CO2 seems to be the normal way its done, often the tank is steam cleaned first.

Twenty five years back when doing my weld certs training, I was asked to braze a leaky motor bike tank along a section of it's monkey grip type seam.
Having undergone said training I thought it was okay maybe, if it was decreased,then steam cleaned.

It happened after degreasing, steam cleaning (twice ) and filling the bastard with water ,that I took to it with an oxy set and brazing rod.

The tank was an old Honda type that had a valley through the tank to accommodate the frame. Filled with water and capped I tied up side down it with 10g baling wire to a fence rail.

About 10 secs after getting the braze to run the thing when it went kaboom. It did not quite tear off the fence,but left us with our ears ringing, covered head to foot in water, and removed the little inletted knee bumps as features in the in the tank.

I declined further attempts at repair.

That was my last experience with welding on fuel systems.

I offer no other advice other than to be very,very,careful!

It is not worth it.

Grahame