Welding On A Used Metal Gas Tank

[digger doug]

Originally Posted by Ironman

Yep, same as the propane stink, it goes into the pores.

Which is why I prefer to either flush with enough air to lower the concentration below the explosive range, or my preferred method, which is engine exhaust to remove the air from the triangle.

My concern with those 2 methods, is when I start making the cut, I open things up, and air can go in.

[MetalWolf]

Another point I'd like to make on this subject... In today's market, it is cheap enough to go buy a piece of pipe and end caps to fab up about any small project tank and even a larger trailer bbq pit project and the cost far outweighs the risk of injury or death...

and would be my suggestion to anyone who has not cut propane cylinders or on fuel tanks... always think safety first because there is never going to be a full-proof method of welding or cutting on a fuel container that has been in use or out of use for a short time... I've seen propane cylinders go off after 8 years of setting with an open port.

and that comes from a guy who buys the large propane cylinders opens them up then they sit in a field numbered and dated and when he's ready for the cylinder to be used fills them with soap and water till no foam comes out
then track loader them on to a huge bone fire pile and stacks a crapload of wood on the top as well and burns them...
but he has the time for all that most want to just do the quick fix or quick project foolishly using freshly used fuel tanks and those I will always walk away from.

[arizonian]

Originally Posted by digger doug

A leetle story, maybe some info can be gleaned from it.

about 30 years ago, was hanging out at a garage, the owner, about 74 years old, had a farm skid tank he wanted to cut open.

He had done plenty of welding and cutting thru his life, and did not take risks.

He brought the tank down to the shop from the farm, it had gas in it prior.
He said he left it empty and open for maybe 10 years, but didn't trust it.
Sniff testing didn't show any fumes (our noses, not a 4 gas monitor)

So we filled it up to the very top, left the hose running (pouring out the top bung).

Using a stick welder to cut it, I struck the arc, and proceeded to safely cut the top off.
Why not a torch ? Well, the water started coming out the cut line, but the welder just plowed on thru, the torch wouldn't like that at all.

However, as the water lever came down about 12" (where the cut line was)
we found a rainbow slick of gas floating on the top of the water, that had "come out of the pores" as we heated the metal. It didn't ignite, but after all these years, was still in there.

This is one of those threads that posters argue about how to do something 10 different ways. With that said, I'll put my .02 in.

Working in Colorado for an oilfield outfit, a customer brought in a water truck that he had also hauled crude oil in at times. He wanted a manhole at the back of the tank. We filled the tank with water and then proceeded to cut the opening with a torch. After the water had drained down a bit leaking thru the cut, the cutting started making popping noises as the "fuel" in the pores ignited. Since it was still 99% or better full of water, it was more of an annoyance than anything, but it did open my eyes as to what can ignite.

I like the idea of using a welder turned up and 6010/6011 for the cutting instrument. I'll just have to file that one away.

[toprecycler]

Originally Posted by MetalWolf

Another point I'd like to make on this subject... In today's market, it is cheap enough to go buy a piece of pipe and end caps to fab up about any small project tank and even a larger trailer bbq pit project and the cost far outweighs the risk of injury or death...



and would be my suggestion to anyone who has not cut propane cylinders or on fuel tanks... always think safety first because there is never going to be a full-proof method of welding or cutting on a fuel container that has been in use or out of use for a short time... I've seen propane cylinders go off after 8 years of setting with an open port.



and that comes from a guy who buys the large propane cylinders opens them up then they sit in a field numbered and dated and when he's ready for the cylinder to be used fills them with soap and water till no foam comes out

then track loader them on to a huge bone fire pile and stacks a crapload of wood on the top as well and burns them...

but he has the time for all that most want to just do the quick fix or quick project foolishly using freshly used fuel tanks and those I will always walk away from.

In my opinion, leaving the propane tanks open for years with no valve is worse than starting to cut a tank that had gas in it as you remove the Valve. Reason is, with the tank just removed valve, there is no air/ oxygen in the tank, only gas fumes. They do not burn until mixed with the outside air.

The tanks that had valves removed for years have had ample time for air to go into the tank, and then you have the explosive danger. I think it has to be about 90% air to 10% gas for it to be explosive.

My dad used to cut open 500 gallon propane tanks and used this method.

With that said, a 100 lb propane tank exploded and killed him 20 years ago. But he was not cutting that one open. And for the record, I have cut tanks open since his accident, so I am more cautious now, but also more educated too.

A tank used for gasoline is more dangerous than a propane tank because it is not under pressure like a propane tank and can have air inside more easily, so it needs to have more precautions taken.



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[midmosandblasting]

I know it is done. As a kid I used to hang around a tractor wreck yard . Some of the tanks had been setting open for years cap off ,filter assembly off. Before he would load for scrap they went into a fire. It always amazed me the number of them that would blow torch . I just have never trusted myself to eliminate one of the fire triangles .
Prior to anyone caring if a scrap yard burned off the fluff .

[digger doug]

Originally Posted by arizonian

I like the idea of using a welder turned up and 6010/6011 for the cutting instrument. I'll just have to file that one away.

I changed my technique as of late.....I bought a used plasma cutter (hypo max 40)

And I cut up (2) pick up gas tanks same method, but with plasma.

With the HF start, I simply triggered the torch once to get the air flowing,
then put the torch on the tank, and hit the trigger again to cut.

I didn't want water in the tip.

[digger doug]

I had a good friend do a portable job of cutting a hole in the top of a 10,000 gas tank, re-used by a poor country municipality for storing brine water
(they got it for free, instead of buying road salt)

So he's telling me (afterwards) he's straddling the tank up on top, it has maybe a 12" hole already, they wanted a 3' hole.

Tank was pretty full, maybe 12" below the top.

Lights torch, starts blow, and "boom" he get's drenched with brine.

'What in the heck ? it's full of water !"

I said "Doo you know where they get brine from ?"

"No"

I said "They get it from gas wells, if you bang on the tank, it bubbles up
like carbonation"

Jesus.

[digr]

I have cut and welded both propane bottles and gas tanks plus fuel tanks with no problem and all I will say is that I used air. Some people say that I am nuts or lucky, I have taken gas tanks and dumped all the gas out that I could and cut and welded them. Again I will not say what method I used because I don't want anyone to get hurt following my directions.

[Spencer]

Drained the remaining gas.

Hooked up air line and ran quite a bit of air through it to evaporate any remaining liquid and try to evacuate the fumes.

[Spencer]

Went and bought some materials.

Cut and bent a matching bracket.

Figured out where to mount the anchor points.