Welding on gas tank

[chuck]

I use welding gas and plug all holes except 1 to purge the gas. you can smell the fumes to know when it is safe to weld. I would susjest you take it to a rad. shop, it wont' cost that much to have it done

 

[flousberg]

I think I have access to a bottle of CO2. I plan on plumbing it into the pickup line so it goes in at the bottom of the tank. CO2 is heavier than air and the fumes so it should push out any fumes and O2. This seems like the best way. If there is not O2, there cannot be any combustion.

 

[chuck]

You are right, fire must have 3 things. Fuel, O2 and spark. In the right amounts You can not get ALL the fuel out of the tank and any is too much, and you are making plenty of spark so the only thing you can control is the O2. zero O2= zero fire. High O2 will also = 0 fire, that is why dri ice works. I just don't know how much dri ice is enough. There are meters available but I don't have one.

 

[ransil]

I have seen the exhaust from a running vehicle plumbed into the tank, most holes plugged up except one vent hole.

 

[trailpsycho]

Dry ice is CO2 (carbon dioxide) in solid form...its condensed till its at its freezing point. It can give serious burns if left on bare skin as its temperature as a solid is -70 Celcius (minus 70 degrees Celcius is -94 degrees Farenheight, which is very, very freakin' cold). As it warms it evaporates and skips the liquid phase... Make sure that if you do put dry ice in a sealed or enclosed vessel that you have two things, ventilation for yourself, so you dont suffocate (you cannot breathe CO2) and 2) a hole to allow the CO2 gas to escape.

Put a few small cubes of dry ice into a plastic coke bottle and leave it out in the sun...boom.

Be safe.

John

 

[flousberg]

I absolutly understand the chemical reactions that take place during combustion and what is required for an explosion (rapidly expanding gas in a confined space). I am going to let the tank sit over the weekend and make sure all the gas has evaporated. Then I am going to purge it with CO2. When I don't smell gas fumes, I am going to use a long pole with a burning rag attached to the end, stand behind a barrier and put it near the tank with the CO2 still purging. If not flaming occurs, I am going to keep the CO2 purging at low volume just to keep it moving through the tank then weld it up.

 

[PsYcHoBrOnCo]

anyone that welds on a gas tank is a FOOL, i had to work a death at a savage yard years ago where a dummy was welding on a gas tank with water in it and the tank ignited ,we never found the welders head

Does not sound like it was water in the tank.....

 

[67ster]

I'll vote for the inert atmosphere approach , either CO2 or a couple pounds of dry ice if available . I tried the tank full of water years back and couldn't make a good repair .

 

[flousberg]

I washed the tank out last night with hot water and powder laundry determent and dried it out. I checked it this morning and there is only a very slight smell of gas. It is suppose to get to the 90's today, so I am going to let is sit out and see how it smells this afternoon and will probalby wash it one more time. The hot water really evaporated any gas left in the tank I could really smell the fumes coming out as I poured it in. I am still going to purge with CO2 as I weld.

It also helps that the tank is very clean on the inside with no rust at all. I could see where it would be very difficult to get the vapor levels to a safe level with scale in the tank.