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Underwater welding, has anyone here ever done it?

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  • matkra
    replied
    There are other welding process that can be done underwater but they are usually done around a cofferdam, A cofferdam is a housing that is put in place and made dry but under pressure and the work is all done in the dry with the diver moving between the work and the surface using a pressurized diving bell. once the divers reach the surface the bell mates up with a recompression chamber in which the diver live until the project is completed. The whole time they are kept at the same pressure equal to the depth they are working at. This is known as saturation diving. The reason this is done is because the gases that are absorbed into the body/bloodstream reach a point to where the decompression takes the same amount of time weather the diver is under pressure for a day or a month. for example Decompression can take days for a single dive of less than a day depending on the depth. The breathing gases are not the same as one would breath on the surface, it could be helium/oxygen mixed at a ratio that may not support human life on the surface, This area of diving becomes very tricky because may things come into plan, I.e. helium removes body heat very fast just through breathing alone. so the diver body is kept warm by pumping hot water to the suit and a heat exchanger the the breathing gas passes through. The have been many deaths in this type of diving. that is why the divers get paid so well. However if you think you can get certified welding underwater, you can but that does not big money make. since the 70s-80s divers were in great demand so all kind of schools sprung up. I got my training via the Navy/Army/NOAA So diver have become a dime a dozen and often work as a tender for years at min wage on a Gulf oil rig. before they even get wet. By the way is is easier to teach a good welder to dive, than it is a good diver to weld. Many new people to commercial do not realize the diving is just a mode of transportation to get you to your work. One need to know something when he get there. I had my own business up here in Seattle and had 5 employees. it a rough living at best. I work on dams, had a couple of mini two man subs and remote control vehicle and a whole bunch of really expensive stuff. I no longer dive anymore, I sold my business about 7 years ago. while I was ahead it;s a young man;s line of work for sure. Here is a photo when I was testing out the newly build hull.
    http://machinebuilders.net/absolutei...ubmarine02.jpg and this is one of my diving boat. http://machinebuilders.net/wwforum/u...ieverSmall.jpgBo th of these were built in my shop.

    [This message has been edited by matkra (edited 07-28-2005).]

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  • Mcostello
    replied
    Some of you guys make my job so darn BORING I should scream!

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  • charlie coghill
    replied
    Matkra, thanks that was very interesting. I have about as much interest in diving as I do in skydiving but I do find thangs like that interesting. Thanks.

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  • Cecil Walker
    replied
    I too enjoy the wealth of knowledge from the members of this board. keep it up.

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  • andy_b
    replied
    Matt,

    i'll also chime in. i found your post very informative. feel free to post more on the subject.

    andy b.

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  • Mcgyver
    replied
    Matt, thanks for all the info, likewise always wondered about it

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  • Wirecutter
    replied
    Matt -
    I don't think you gave excessive info - I for one would read more if you posted it. This is exactly the kind of thing I count on here - I figured eventually an underwater welder such as yourself would chime in.

    You'd be amazed at the range of knowledge behind the eyes of this board's readers.

    -M

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  • Bullpit
    replied
    no I havent,it pays so well because it's cazy.



    [This message has been edited by Bullpit (edited 07-28-2005).]

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  • Evan
    replied
    It's not something I'd want to do. The occupational fatality rate for commercial divers is 40 times higher than the general population. That's why it pays so well.

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  • Rustystud
    replied
    Welding under water:

    Look at CDC: Comercial Diving College in Longbeach California They teach underwater welding as well as underwater demolitions. The entire course is about a year long. Welding under SAT conditions pays $400.00 to $900.00 per hour. The shortest time you could be under SAT conditions is about 48 hours. They will usually keep you blown down at least 4 atmospheres in a chamber while you are not working. There are some long term health concerns. Bone necrosis and emboli in the organs.
    Check it out.
    Rustystud

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  • fencepost
    replied
    Matt,

    FANTASTIC, exactly what I was looking for!!

    Now it looks like I need to do more research into the topic, just because I'm interested. I'll probably never have the opportunity to try it, but it's nice to know anyway. More stuff to think about, more stuff to learn about.

    Thanks Matt,

    Axel

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  • Steve Stube
    replied
    Thanks Matt, like fencepost I have wondered about this too and I appreciate your taking the time to put it into words. Is there a certification test for underwater welders? Do weld test get preformed during a repair or at dry dock? or never? Can one lay down a bead that appears like that of the out-of-water welder? What does one do about welding at or near the water line? Do you put on lean on the ship by shifting weight to make it either underwater or out-of-water welding? You must have atleast one "rough sea repair" to share, right?
    Again, thanks for what you have given us already.

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  • Evan
    replied
    Cool. Definitely not too much information. Can you do anything other than stick welding?

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  • matkra
    replied
    I had been a commercial diver for over 20 years. Welding underwater is not as bazaar as it may seem. First of all we always used DC welding, there is a tender topside with a big knife switch so the power is off to the stinger until the diver calls for power on. Only then is power supplied to the stinger. As far as eye protection we used a flip up lens if we're working in very clear water,(which was almost never) the lens made especially to attach to the divers helmet. If we do allot of welding we bolt on some zincs to our helmet to counteract the electrolysis in the metal part of our gear. We usually ware rubber gloves and I have on occasion work with out them it tingles a bit.. In very turbid water no welding lens is needed because the UV has a very short range underwater it has never been an issue for me. The rod is coated with water proof coating, but I have in emergencies used 6014 wrapped with electrical tape which worked surprisingly well. One also has to keep the ground very close to his work to keep stray currents in check and never get between your work and the ground electric will always take the path of least resistance, so you do everything you can not to be in the path. Short of that is like welding in space. For UW cutting we used Broco torch and rod. the rod is really a copper coated tube about 3/8" ID and inside the rode is a bunch of smaller rods made up of magnesium. They are arranged in a circle pattern inside the copper coated rod. all of this fits onto a special torch that has a power cable and oxygen hose running the power can come from either a DC welding machine or a battery like a car battery. it is used only to lite the torch. the diver will pull the trigger to allow oxygen to flow through the copper tubing and when the power is turned on the diver strikes the rod on the grounded steel. the torch will ignite because of the magnesium and oxygen as long as the oxygen flows the torch will stay lite. the tip temp is about 10,000 degrees and will cut through just about anything ferris or nonferrous,concrete, wood, I have used it to remove thousands of feet of sheet piling and bridge strand cables over 3 inches thick. and it fun too. But is your working around concrete is sometimes explodes a little. One of the things that can happen when welding under a ship hull is the hydrogen gases can collect in an area like a sea chest and then explode if your are working in that area. So we always have a ventilation hose blowing air into the sea chest. This is probably more that you wanter to know about underwater welding and cutting. But I get started and I just can't stop. My wife say I just making up for all the time alone underwater with no one to talk too.

    Matt

    [This message has been edited by matkra (edited 07-27-2005).]

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  • Fasttrack
    replied
    It was my understanding that underwater cutting is done with a powerful oxidizer. For instance, salt peter (sodium nitrate) actually produces oxygen as it burns (thats why firecrackers will still go off if you light them and throw them in the water). To cut underwater you need a very localized heat, but more important than the heat is oxygen to burn the iron away. Once that rapid oxidization reaction has begun heat is no longer neccessary. Another example of this is rocket nozzles. If you were to cut the nozzle out of steel, the hot gasses, although not hot enough to turn the metal molten or even red-hot, are actually high in oxygen content so as the gasses leave the rocket body, it causes the steel to corrode very quickly.

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