I just saw a tv commercial from a boat company, trying to sell their goods, as well as mentioning they do boat repairs. They also said they are equipped to weld under water. I never heard of such a thing. How the heck do they weld under water. That does not seem possible. For one thing the electricity will not conduct, and-or will electrocute the user. And even if they can, wont the water cool the weld as soon as it's applied?
I'm sure they do it, if they advertise it, but how?????
Absolutely. I am not even going to try to claim expertise, but it is done all the time. On the bigger scales, that is how deep sea drill rigs and other underwater construction is done and maintained. Here in middle America, I watched the glow from below as a fellow did repair on a floating marina on Table Rock Lake a couple of years ago.
RonB
I am a welder of 30+ years and have worked topside while welders were under the water welding patches on moored ships etc. Welding is done in DC and will work underwater.. the ground is kept as close to the weld as possible to prevent the electricity from going through the path of least resistance. Constant radio contact is kept with the diver... he will weld about two inches then have the welding machine topside shut off so he can reposition his ground...then give word he has moved his ground along and welding machine is fired back up for the next weld. The welding rods are not much unlike the ones we use in everyday use....such as a E7018 electrode is used in a lot of applications....that type of welding rod is nicknamed "low hydrogen" welding rod because water will actually contaminate the welding rod leading to porosity. What they do with the welding rods is dip them in shellack so it burns off under water and is not directly exposed to the water before striking the arc... The surrounding gases produced by the shielding flux protects the molten weld puddle as it solidifies..........that is to put it into a "nutshell" to explain any more would only cause great confusion...Google underwater welding and read for yourself... Jim
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Welders are high current but LOW voltage. Low voltage will not travel much in water and the welds cool real fast under water. You can also weld with gas underwater because all that is needed is supplied from tanks, oxygen and acetylene.
If it's on TV, it has to be true, right?
I was a commercial diver from 1974 to 1980. We were taught welding in diving school, but there isn't really a lot of it done in the field, except where the weldment can't be brought to the surface, welded in air, then reinstalled. It is claimed that an underwater weld can reach 89% strength and 50% ductility because of the quenching effect of the water. Most divers are not good enough welders to achieve this. Some things that are critically welded underwater are "habitat" welded where essentially a bubble is made over the weldment, and then the welder can go into the tiny space to make the weld in air. On some projects, the welds all consist of a similar fitup, such as a SPAR, or Subsea Pipeline Alignment Rig, and that is big enough to clamp on to the pipe and give enough room for a welder to work. On all the other noncritical work, such as structural, it is done with 6010 or 7018 rods, and a lot of hope.
Yes, you can get shocked, but it's not bad. It will corrode the metal on your helmet if you do it a lot. People who do it a lot have a sacrificial helmet or band mask that they will use only for welding. Google commercial diving helmets, particularly Kirby-Morgan.
Steve, welding since 1974
"Steve B" wrote in news: snipped-for-privacy@news.infowest.com:
Inspired by?:
Did you know that concrete hardens underwater too? Ever since Roman days.
I have gotten shocked from my stick welder when welding on vehicles or other things, outside when the ground is wet, and my shoes are wet too. It cant kill, but it sure can sting. I quickly learned to stand on a piece of dry plywood and/or put on waterproof footware.
Ever done it? OA burning CAN be done underwater, but the modern electric hollow burning rod is preferred.
Apparently, it has come light years from what it was when I was in the water regarding underwater welding.
Very carefully?
Sorry about the joke sci.engr.joining.welding
Jimmie
I went down to the open house at "Divers Institute of Technology" to meet Ernie in that group and see where he works, and watched on a TV monitor as a diver 15 feet below welded for a demo. Fascinating.
Lloyd Bridges and Sea Hunt, actually. I learned to scuba from Harry Wham, a retired Navy hard hat diver who taught Lloyd Bridges to dive.
Steve
Any time you mess with electricity, it will eventually end up biting you. No getting around it. AC welding is the worst.
Steve
You pour it through a pipe called a tremie. Does a decent job, actually. Used on pier pilings a lot. Jet around the piling and then pour concrete through a tremie.
Steve
Doing that for six years was like getting to be a pirate and an astronaut all rolled into one. Not everyone gets to do it. It is fascinating, dangerous, dirty, scary, cold, a lot of fun, and at times bone weary work.
Steve
An AC bite never bother me as much as DC. You will know if you have ever gotten hit by a 280 volt UPS battery.
Jimmie
Actually that would be good, because when you touch the electrode to the work, it won't depend on the water to conduct.
But water with various things disolved in it, and even moreso salt water with other things dissolved in it too, will conduct better than air will. So too I learned from this thread how they avoided that.
"Steve B" wrote in news: snipped-for-privacy@news.infowest.com:
I don't think I missed an episode of Sea Hunt as a kid either.
Well, have you ever had an arc jump to your hand from the horizontal output tube anode cap of an old 25" color TV. I excused myself from the presence of the customer, walked outside, made all sorts of noise reminiscent of The Three Stooges, then returned to finish repairs to his TV.
TDD
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