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How do you decommission a bunch of CNG tank?

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  • How do you decommission a bunch of CNG tank?

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  • #2
    Re: How do you decommission a bunch of CNG tank?

    Drill at least 2 holes in each tank a minimum of 1/2" in diameter and remove the caps on both ends.

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    • #3
      Re: How do you decommission a bunch of CNG tank?

      CNGvw, looks like your location to decommision is out in boonies so safer than populated area.

      Are there any requirements to have temporary "cage" or fixture to prevent the tank from flying around under the worst-case scenario of valve failure / fire upon venting the cng tank??

      Also, hope you're getting paid pretty well for that dangerous job of decommisioning those tanks!

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      • #4
        Re: How do you decommission a bunch of CNG tank?

        The job went well. I did have to make up a hand full of Manual relief tools and 2 high pressure hoses with dump vent tubes stands. You will not lose control of the tanks they just weigh too much. You can and I did lose control of a hose one time. Use a lot of rocks to hold it down. When you power up the relive valve in the tanks it can take a long time to dump 14 GGE. So the best way is the do it manually
        It takes some skill and balls to boot. We had them line them up like cords of wood and then just worked my way along. I followed the GGA C 6.4 guide lines there is not a lot of information of this kind of work.
        The point is there are piles of these tanks in many junk yards and no one knows what to do with them. Some are told just drill a small hole in it and it will bleed out. The only thing that will bleed is your head when it is blown off. So what are they to do just leave them to pile up to rust out and leak uncontrolled? Or when water makes it way down the valve and freezes and pushed the valve back and leaks.
        It is about safety for every one living and working near a pile of tanks or just one. The sad part is you are going to vent it in to the air 99% of the time. As a CSA Certified CNG Fuel System Inspector I am the closes thing you are going to find around here that has a clue, have done about 40 tanks use the same guild lines ever time and have made up some of my own safety tips and hardware.
        Bob Mann

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        • #5
          Re: How do you decommission a bunch of CNG tank?

          I hope anyone reading this thread will also take a close look at the Clean Vehicle Education Foundation's guidelines for decommissioning CNG cylinders here:
          http://www.cleanvehicle.org/committe...sposeFinal.pdf

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          • #6
            Re: How do you decommission a bunch of CNG tank?

            John thanks for posting the booklet. It is a scary thing to do any way you look at it. In the North East the CNG market is a very slow thing. So these state CNG cars and trucks busses get junked and then the tanks just pile up.
            Bob Mann

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            • #7
              Re: How do you decommission a bunch of CNG tank?

              am I missing something here ? we are trying to keep the air clean burn the gas in a flare! cng in a greenhouse gas . and it can not blow up as it cant build up if it is burned .I made mine out of a piece of 7 inch well casing and a plate welded on one end with feet so that it stands up and holes drilled in the sides of the big pipe to let air in 1 inch above the plate 1 inch holes and one hole drilled and taped for a 1/2 pipe thread in the middle of the flat plate a street 90 gos in the threaded hole and then a piece of 1/2 pipe about 5 foot long than a valve rated over 3600 than a hose to hook to the tank take a piece of news paper light it drop it in the top and crack the valve and presto you are not letting raw cng in to the air when the flare gets good and hot you can open the valve more I have had flares 50 foot in the air real cool blowing down racks of dot bottles before transport for hydro what is the point of burning clean fuel if we turn around and dump raw fuel ? shame most gas co wont let it be dumped with a regulator back in to there lines

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              • #8
                Re: How do you decommission a bunch of CNG tank?

                Here's an updated link to post #5 describing the requirement to drill holes in an expired CNG tank. Federal Regulations (49 CFR 571.304) require that a CNG cylinder be taken out of service at the End of Life (EOL) date. To prevent reuse the cylinder should be destroyed.

                http://ngvamerica.org/pdfs/TechBul6.pdf


                I must conclude that the Public Surplus auction this week of an expired CNG tank is a violation of Fed Regs since the tank has not yet been destroyed.
                .

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                • #9
                  Sorry to revive an old thread, but I am unable to find info else where. We just had to replace two fifteen gallon tanks, and I was looking to use the old ones as additional storage for compressed air(we do some painting). How would one clean out the tanks once they are empty? A clerk at a local Airgas mentioned an expensive soap/chemical big corps use on cng lines/pipe, but he couldn't remember the name. Any ideas? Thanks.

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