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  • underwater cutting torches

    How do underwater torches work,what kind of gases do they use and how do you light them?

    Jim W.

  • #2
    I'm pretty sure they use oxygen and mapp gas, and are lit before the torches are submerged.

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    • #3
      Jim,

      Not an expert here so I'll get the topic off by stating what I know.

      One method of cutting underwater is the oxy-hydrogen process. This involves the use of compressed oxygen, compressed hydrogen, and air under pressure. The technique does not differ radically from open-air cutting practice, since the torch performs in much the same way as a standard torch being operated in air.

      One thing that sets underwater cutting apart from ordinary cutting is that underwater cutting requires the operator to become accustomed to working with relatively high gas pressures. These pressures must increase with the water depth at which the work is being performed. Mechanically, underwater cutting is accomplished by the same means used topside, except that an additional hose is used to deliver compressed air to an air shield, or skirt, that surrounds the cutting tip and sheathes it with a bubble of air.

      This shield is not necessary to keep the flame alight in that the fuel gas and oxygen support combustion even when the flame is emmersed in water. The purpose of the shield is to stablize the flame and hold the water away from the area of metal being heated. The higher pressure in underwater work is necessary to provide the required increase in flame intensity and to overcome the water pressure at whatever depth the torch is being operated. Hydrogen therefore, is the fuel gas used almost exclusively in this type of cutting, because it is generally unsafe to use acetylene at pressures higher than 15 pounds.

      Lighting the torch can be accomplished above water or below the water. To start the torch below the water, a special electrical lighter has been developed.



      [This message has been edited by Mike Burdick (edited 06-06-2004).]

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      • #4
        Just a guess but I'd bet that Evan might have something to share on this. I believe he has spent enought time underwater to grow gills.

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        • #5
          Huh? Aside from the fact that when I was a child I could swim the length of an olympic size pool underwater on one breath I have no particular special underwater experience. Been down in a pool on SCUBA once. Never welded underwater. All I know about underwater welding is strictly what I have read.
          Free software for calculating bolt circles and similar: Click Here

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          • #6
            Thanks for all the replys,especially from you Mike,that was informative.I feel a little less dumb now.

            Jim W.

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            • #7
              Jim,

              Are you planning on doing some underwater cutting?

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              • #8
                In answer to your question,Mike the answer is not no but hell no. In fact I'm not even going in a pool and if the shower drain does't stop up my toes won't even get under water.

                Thoughts go through my head all the time and this information might be pertinent to one of them. I would tell you about it but I don't want you laughing at me.

                I looked this subject up on the internet and some company in the Netherlands makes an underwater torch that uses compressed air and oxygen but for fuel they use propylene gas. Their claim is that it cuts faster than hydrogen. All I ever heard of is polypropylene which is a solid, I think.

                Another trip to the internet shows that propylene gas is evidently the same as MAPP gas.

                Thanks again Jim W.


                [This message has been edited by drof34 (edited 06-08-2004).]

                [This message has been edited by drof34 (edited 06-08-2004).]

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                • #9
                  you might find this interesting:
                  http://www.sonshipindustries.com/rgastorch.htm

                  -tony

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