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Thread: Some questions concerning underwater welding

  1. #26
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    Re: Some questions concerning underwater welding

    The umbilicals we used were made up of your main air hose, a communications cable and a smaller air hose called the pneumo hose. The comm cable also served as the strength member of the bundle. The pneumo hose was open ended (at the diver) and you had 2 to 3 foot extra of it that you wound up and tucked under your harness strap to keep it out of your way. It was mostly used for keeping track of how deep you were. When you hit the bottom the radio operator would turn the air on to it and you'd tell him when you saw (or felt) bubbles coming out of it. He'd then shut the air off to it and a gauge on his console would measure how far the water would flow back up it and it would read how deep you were in feet. We also used this hose to inflate air bags when trying to lift stuff that way. In an emergency if something happened to the main air flow to your hat you could shove the end of it up under your neck dam and keep air in your hat that way (luckily never had to do that).

    We hardly ever just jumped in the water and fell to the bottom like you see in these movies or internet videos. It may look sexy but it's mostly just a good way to get yourself hurt. We usually had a ladder that went two or three rungs down into water that you crawled down. Then the tender would then throw enough slack in the umbilical that you could grab on to it and slide down to the bottom in a controlled fashion. When you were ready to come up the tender took a strain on the umbilical and you climbed up it hand over hand until you could grab the ladder. Then you waited until he could gather in all the slack so you wouldn't get tangled in it when you were climbing the ladder. He could also help you up the ladder by pulling on you some.

    Keeping track of your umbilical and which way it got run over, under, around and thru things was always kept in mind. Having to trace your umbilical back and unsnag it from something happened often. When I got to where I was going to be working I always called to have all my slack taken up until I felt the tug and then asked for 2 or 3 foot back. For got to do this once when burning and had a good sized piece of a fractured concrete collum fall across my umbilical when I got thru the last rebar. The spiral wire holding all the chunks together was to big for my side cutters to get thru and they had to send a pair of bolt cutters down so I could cut myself free of it.

  2. #27
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    Re: Some questions concerning underwater welding

    So this one time I was a pretty good ways up a 3' diameter intake pipe full of silt.... I'd gotten to the point that my bail out bottle was jammed against the top of the pipe and I'd been digging my way forward for a while. I was starting to get pretty anxious about where I was and stopped to consider what I should do. I had the main valve on my air block cracked wide open trying to get a good flow of cool air. I'd come to a complete stop and was seriously considering telling top side that I couldn't go any further....all of a sudden something just slammed into my hat and beat it's way down past me. It scared the hell out of me so bad I'm sure I peed myself. There was so much silt stirred up that it was like being in a glass of chocolate milk. I had turned my helmet light off earlier (to save battery power) because it was doing absolutely nothing for me so I was in complete blackness and never saw anything of what hit me. Best I can figure it was at least a 3' long catfish who'd been making his home up in this pipe. I squeled so loud I got topside all panicked and they were asking me if I needed the stand by diver. It took a few minutes but I got myself under controlled and backed my way out of the pipe (which probably took 10 minutes) and climbed my umbilical to the surface. That was pretty much it for the day. Spent the next 2 days working with another diver (mostly with us both in the water at the same time) running a suction lift to clear the silt out of this pipe so we could get to a gate valve further in. We cleared a submerged log that was keeping the gate valve from closing all the way tight.

  3. #28
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    Re: Some questions concerning underwater welding

    In clear water, where I can see what I'm doing, I can get thru a 2" rebar in 5 seconds with a Broco exothermic rod (90 psi on the O2). In zero visability I've spent at least 5 minutes trying to cut one off at the mud line. I've cut at least 800, 2" rebars off at depths running from 20 to 50 foot. Most of those have been done 100% blind. You don't need a flip down lens because at most you only get an occasional glimpse of a diffused orange light. I've had the ends jump around 18" because of the stress on them.

  4. #29
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    Re: Some questions concerning underwater welding

    Getting stuck in the head down position under water is not a good thing. I don't care how good your neck dam fits your hat is eventually going to fill up with water. The only hope you've got when being upside down is to be able to crack your main air valve all the way open and have a good supply of air from the surface. If you've lost you're surface supply and are just on your bail out bottle you don't have much time before you're in serious trouble. I've purposely been head down underwater in a SuperLite 17B to be able to crawl down in to a tight space. I've had to have the air valve of the main block all the way wide open just to keep the water out of the hat. The trouble with having your air block open to far is that it's so noisy that it blows out your comms and you can't understand a thing that's being said to you (or vice versa). You end up having to make the choice between breathing or being able to communicate.
    Last edited by HT2-4956; 11-22-2014 at 03:18 AM.

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