Plump your exhaust to the fill hose and undo every hose to let the exhaust gas out..Quote:
Originally Posted by dom14
Nitrogen from a gas supplier.
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Plump your exhaust to the fill hose and undo every hose to let the exhaust gas out..Quote:
Originally Posted by dom14
Nitrogen from a gas supplier.
Use a longish hose or run the hose through a bucket of water as they can get Dam hot.
Any BOC, Supagas or air liquide outlet can hire you a cylinder, but exhaust gas is the cheapest option.
As you won't have fuel in your tank to run the car use a motorbike or mower.
It's all the same.
Purging of the petrol tank is done to get rid of any left over petrol in the tank, right?Quote:
Originally Posted by rusty00
So, it won't "explode" while trying to weld the crack.
What if, after draining all the petrol, I leave the tank out in the sun for few hours for any left over intank petrol fume to get out??!!
I understand that means pulling the tank out. But, I always thought, in order to do a proper welding job of satisfaction,
having the tank on a bench is the ideal thing. Welding stuff under a vehicle(with no access to a hoist) is easily said than done.
While doing welding work on the van chassis(no hoist). I had to use quite a few of tree trunk cut outs to raise the van high enough to be able to do all the welding work. Even with that, it was a bitch of a job. I use the same thing to raise the rear of the vehicle high enough when I was doing the rear diff center.
It won't rid the tank of fuel, but it will creat an environment where an explosion can't happen by removing the oxygen.
If you have no oxygen then no fire can start.
It is best to remove all fuel any way you can to be sure and to make sure you are happy with the process.
If you have a mig welder and can access the tank crack you will be okay as long as you can squeeze yourself or the welder in place.
We use to use this method to cut tanks in half and weld when fitting gas tanks and also for repairs.
Never ever had a problem.
Since the crack was due to a stone, would you drill a small hole at each end before welding it anyway?
That means the tank has to be air tight while welding, otherwise oxygen would squeeze in, regardless of the purge.Quote:
Originally Posted by rusty00
Why wouldn't oxygen get into the tank from the very crack you're trying to weld??!!
I'm bit lost!!! Drilling into the tank?Quote:
Originally Posted by mudnut
When we had cracked components on locos or whatever, we would drill a hole at each end if possible so that the crack would not continue after the weld was done.
No, just purge it or wash out all the fuel or take it to a professional.Quote:
Originally Posted by dom14
The crack has nothing to do with the oxygen, you are removing the inner space oxygen with the purge.
I'm sure you are right, as you have experience of doing it. I'm only trying to understand as I haven't welded a petrol tank before. I' guessing you use exhaust gas to purge any left over fuel(from hot exhaust gas)?Quote:
Originally Posted by rusty00
Or do you need to keep the engine running, while the exhaust is attached to the petrol tank & while you're welding?