Underwater welding, has anyone here ever done it?

[fencepost]

Underwater welding has mystified me for years. I've seen photos of it, seen the results (on the surface, the thought of breathing underwater is not natural to me). I ponder things like the welders goggles, how do they work with a mask or hood? AC or DC? How do you shield the molten pool? Insulating yourself from the electrode? Is salt water easier to weld in, or is fresh, or does it matter?

I've done some reading on it, but most implies the reader has experience. I peed on an electric fence once, does that count as experience (I was very young - haven't done it since, guess I learned from that experience, eh)?

Can anyone share any thoughts and ideas?

Just wondering,

Axel

[Boucher]

Texas State Technical Instute at waco had a course in underwater welding. The campus is on the old James Connally AFB. They had a Lab in an old fuel storage tank. There was a portal in the tank where you could watch them practice. Lots of safety issues but the guys that do repairs on the offshore rigs get top dollar. Had a friend that went thru the course decided to go into welding quality control after he got out.

[Your Old Dog]

One of my friends just finished up a stint in the Naval Reserves and he taught underwater welding and repair of ships for several years. He got out about the time the Islamic terriorst that we can't profile popped a hole in the Cole.

[3 Phase Lightbulb]

If you live on the East coast and you're doing any welding outside right now (MIG, TIG, Stick, O/A), then that's basically underwater welding... I feel more dry taking a shower than I do being outside right now

-Adrian

[Wirecutter]

Hoffman? Hoffman where are you?

3Phase - it's the same here. Air you can wear.

-M

[Wirecutter]

More on topic here - is underwater welding one of the uses for Thermite? I know it's used on some very large scale welding, like some bridges, and it's very difficult to put out once it's going. It burns underwater, doesn't it?

What is the heat source for UW?

As for safety equipment, maybe you have to worry less about molten slag getting in your shoe...

[alcova]

I seem to have less of a problem picturing welding underwater than... How do you use a cutting torch underwater without the water cooling off everything as fast as you try to heat it.

[Fasttrack]

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.

[matkra]

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).]

[Evan]

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

[Steve Stube]

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.

[fencepost]

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

[Rustystud]

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

[Evan]

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.

[Bullpit]

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



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