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Thread: Opening of Dangerous Tanks

  1. #1 Opening of Dangerous Tanks 
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    All my working life I have heard that there is no safe means of opening a pressure vessel, or tank, which previously contained material such as propane, or LP gas, acetylene, gasoline, and so on. Indeed, I know of an instance where a neighbor's relative was killed while attempting to weld inside of a large, previously used tank (contents I never heard), when vapors inside exploded. I once sought to modify my truck's gasoline tank, expecting to use my cutting torch, first having completely filled the tank with soapy water, drained, and refilled several times, then drained a last time. Being cautious on that deal, I approached the filler neck with my lit torch, and an extremely loud, violent explosion took place, the gases venting through the neck, the tank bulged outwards, but not burst. The report had been deafening!

    The commonest theory I've heard, is that inflammable volatiles enter the "pores" of the metal, and remain after flushing the tank. Always regarded that as utter bullshit, so, firstly, what do the technically trained and experienced Members here know along these lines?

    Secondly, a look below, may convince that I prefer to live on a dangerous precipice!






    The tank above was used to fabricate the boiler for the model seen below:





    Always wondered what wall thickness existed on typical gas bottles, like oxygen, for example, shipped with 3,000 psi contents. It turned out to be on the order of 5/16 of an inch; I had been guessing higher. My old high school friend, Charlie, who obtained a Masters Degree in Metallurgical Engineering while I was diddling with drag racing, was consulted; he revealed such tanks are usually made of 4130 steel, easily weldable. That's what I wanted to hear!

    The mental image of tank size may be transferred to the locomotive, however, there is a one-inch wrap of insulation all the way around it, thus making the finished size 2 inches larger than the tank. jocular


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  3. #2  
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    is there a question hidden in here somewhere?>


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  4. #3  
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    Quote Originally Posted by fizzlooney View Post
    is there a question hidden in here somewhere?>
    I thought so: it's in the very first sentence. jocular
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  5. #4  
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    I don't think water is a good way to remove traces of hydrocarbon. All you need is a bit of a dead leg somewhere with a few ccs in it and you have enough vapour for a bang. With a highly volatile hydrocarbon such as gasoline I think it would be best to to use the hot soapy water to displace as much as possible of the residual liquid and then to pass air through the tank to purge all vapours until the whole thing is completely dry and odour-free. And even then I'd use a mechanical cutter rather than a torch, until the thing was opened up.
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  6. #5  
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    Quote Originally Posted by exchemist View Post
    I don't think water is a good way to remove traces of hydrocarbon. All you need is a bit of a dead leg somewhere with a few ccs in it and you have enough vapour for a bang. With a highly volatile hydrocarbon such as gasoline I think it would be best to to use the hot soapy water to displace as much as possible of the residual liquid and then to pass air through the tank to purge all vapours until the whole thing is completely dry and odour-free. And even then I'd use a mechanical cutter rather than a torch, until the thing was opened up.
    Good points! Another source of potential danger would be repair: an arc welder is no less dangerous than an open flame. I am surprised no one has commented on the appearance of the tank in my pic. Don't know if tank color-coding is international, but here blue is non-flammable gas, I think. The tank pictured contained Nitrous Oxide, which can support combustion I suppose under hot circumstances, due to it's oxygen content. jocular
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    Malignant Pimple shlunka's Avatar
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    I was expecting a thread about grenades being thrown into armored vehicle hatches.
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  8. #7  
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    Quote Originally Posted by shlunka View Post
    I was expecting a thread about grenades being thrown into armored vehicle hatches.
    That experiment of mine is scheduled for airing in the future. Glad you reminded me! When I was a young man, anyone could buy dynamite in most hardware stores, especially those located adjacent to rural or farming areas. Believe it or not. jocular
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  9. #8  
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    I have cut tanks and drums many times, gas tanks are drained, flushed with soapy water and can be flushed with either C02 or auto exhaust gas then cut. sounds more like you are a danger to yourself and society in general
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  10. #9  
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    Quote Originally Posted by fizzlooney View Post
    I have cut tanks and drums many times, gas tanks are drained, flushed with soapy water and can be flushed with either C02 or auto exhaust gas then cut. sounds more like you are a danger to yourself and society in general
    Thank you for the vote of confidence! I never venture out, and thus my stringent belief that if we hurt ourselves, we can blame no one else applies. Also, thanks for providing evidence that others also slice into tanks. Were your efforts done during your work or hobby pursuits? Just curious, not really any of my business! jocular
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  11. #10  
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    working on classic cars, also 55gl drums for bbq, gas cylinders to build bowling ball cannons
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  12. #11  
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    Quote Originally Posted by fizzlooney View Post
    working on classic cars, also 55gl drums for bbq, gas cylinders to build bowling ball cannons
    Fascinating! In MO, I tossed M-80s in the metal drum of my cement mixer; the report funneled out of the thing unbelievably. A neighbor from half a mile away, the closest one, drove over to see what's up. He said he thought I had a "potato gun". Quite frankly, I still don't know WTH a potato gun is! jocular
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    Quote Originally Posted by jocular View Post
    I still don't know WTH a potato gun is! jocular
    PVC tube, potatoes, flammable propellant.

    The best way to watch your redneck friends horribly mangle themselves for life.

    We used to make them when I was a kid.
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    In my experience, you should be able to safely open a tank after you've drained it. I used to work for one of those propane tank trading businesses, now maybe I can't say much about how safe it is to cut a tank with an oxy-ace torch - but I can tell you that we used screw bleeding valves onto full tanks, and then drain the tanks at full blast, all day long. Then we'd rip out the valves, and there wasn't anything particularly dangerous about doing either of those things - you just had to double check the tanks before sandblasting them (they get devalved after being sandblasted). You'd think that if you take the valve off of the tank, before torch cutting it, any residual fumes or liquids would burn off without blowing the tank.
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  15. #14  
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    Quote Originally Posted by stander-j View Post
    In my experience, you should be able to safely open a tank after you've drained it. I used to work for one of those propane tank trading businesses, now maybe I can't say much about how safe it is to cut a tank with an oxy-ace torch - but I can tell you that we used screw bleeding valves onto full tanks, and then drain the tanks at full blast, all day long. Then we'd rip out the valves, and there wasn't anything particularly dangerous about doing either of those things - you just had to double check the tanks before sandblasting them (they get devalved after being sandblasted). You'd think that if you take the valve off of the tank, before torch cutting it, any residual fumes or liquids would burn off without blowing the tank.
    The problem is if you get an explosive air/hydrocarbon mixture inside the tank. I suspect with propane, as it is a gas at NTP, a simple blast of air will gas-free it almost instantly. Whereas with gasoline, you only need to leave a little liquid in a dead leg, or behind a bubble of rust, for an explosive air/vapour mixture to accumulate - and this can easily happen long after the initial venting of the tank. For this reason, the process you have to follow before "hot work" is allowed on refinery tanks and pipes is very elaborate.

    (This is also why there are not - any more - any small boats with inboard gasoline engines. There used to be in the old days, but they've just about all blown up, due to vapour accumulation in the hull, below deck! Diesel is a lot safer.)
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  16. #15  
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    Quote Originally Posted by exchemist View Post

    (This is also why there are not - any more - any small boats with inboard gasoline engines. There used to be in the old days, but they've just about all blown up, due to vapour accumulation in the hull, below deck! Diesel is a lot safer.)
    A fact I agree with. I've often wondered about the horrible jet-fuel explosions I've seen shown upon ground impact; is jet fuel not essentially "dieselene"? jocular
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  17. #16  
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    stander-j apparently has a death wish-no way in hell should you torch cut a tank without back filling with an inert atmosphere. and no its not dieslene-just a higher molecular wt cut in refineing .Petroleum-derived diesel is composed of about 75% saturated hydrocarbons (primarily paraffins including n, iso, and cycloparaffins), and 25% aromatic hydrocarbons (including naphthalenes and alkylbenzenes).[25] The average chemical formula for common diesel fuel is C12H23, ranging approximately from C10H20 to C15H28..
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