Welding in water

I've crossposted this to sci.engr.joining.welding. There's no real electrical principle involved here, unless the current through sea water somehow damages one of those auto-darkening hood lenses.

Good Luck! Rich

Yes, there is an electrical principal, the electric current passing through the salt water to the ground (the current will take every available path) will greatly increase the rate that the chrome corrodes off the brass parts of your helmet. If you happen to have one of the really nice all SS helmets, this may not be an issue. I don't believe anyone uses auto dark lenses for UW welding.

"Pete C." wrote: (clip) I don't believe

^^^^^^^^^^^^^^^^^^^^^ I would think not. They have a circuit board that would stop working as soon as it got wet.

Well, you could theoretically mount it inside the helmet, after all you already have an intercom in there and the water is hopefully not in there since if it is, you have a problem.

Really? When I was growing up, principals were just regular old human beings.

Actually they do. A few years back a company came out with a Autodark lens for Underwater wet welding.

Oh yeah, also if you get your body between the ground and the electrode, in salt water, while the knife switch is closed...

...YOU ARE DEAD!!!.

Not kidding. I teach welding at the Divers Institute of Technology. In fresh water you just get a small electrical shock, but in salt water it is lethal.

Also all underwater wet welding is performed in the DC Electrode Negative polarity to prevent electrolysis from stripping metals from around you and applying them to your weldment. The greatest erosion occurs at the bronze jaws of the electrode holder.

The autodark lenses designed for underwater use have all the electronics completely sealed in silicone rubber.

No you can't. It would violate all safety guidelines by IMCA and the ADC. You can't have anything inside the hat that wasn't part of it's original design. Any dive supervisor who allowed it would be fired and have his card pulled. Same goes for ipods.

"Ernie Leimkuhler" wrote: (clip) Oh yeah, also if you get your body between the ground and the

^^^^^^^^^^^^^^^^^^^^^^^ I would assume, then, that the welding electrode is "cold" until you have it in position to strike the arc, similar to MIG welding. Is this correct?

It is only necessary to wear a lens when welding underwater if you are very close to the arc because the water diffuses enough of the UV rays that if your head is more than one foot from the arc, the intensity isn't enough to burn your retinas.

Also, in underwater welding, there is no movement or watching the puddle. Moving the rod only allows water to get between the rod and base metal, and it instantly cools the puddle. "Underwater welding" is done with a self consuming technique where you crank up the power, put the rod in the crack, and just push it in as you feel it consumed. usually at about a 45 degree angle.

Unless you isolate the weld area from the seawater by a subsea pod of some type of gas, welding underwater with instant quenching is only slightly better than holding things together with hose clamps or bungees. And even with a subsea isolation environment, there are all manner of variables that affect the weld, i. e. humidity, the shielding gas, and inclusions that will affect the x ray or whatever test is required to certify the weld.

It just isn't done a whole lot. Some, yes, but not a whole lot. Most things are brought up, welded, and then taken back down. Or at least that was the way we did it for eight years.

Steve, an ex hard hat diver.

In the old oilfield, a good diver had two hats. One for welding and cutting, and the other for regular diving. Cutting underwater is an electrical process that will corrode the coatings off the helmets and masks.

Steve

Intercoms in a good helmet consist of speakers dipped in rubber. The cheap common way is a condom wrapped around the speaker, and held in place with a rubber band.

Factory speakers are good, and last a good while, but the cost of replacement is so high that when the original set goes out, they are usually replaced by the lesser units, which are far cheaper, and easier to get in the field.

Steve

And tested to what depth? I doubt you could find a depth test rating on one of those. I know I have seen good high dollar watches that were "tested" to

330 feet or something ridiculous, and didn't hold. I had an Omega that I spent big bucks on, and only wore it topside, never exposing it to pressure of more than 1 atm. Brought it to the jeweler when it wouldn't work, and he said the in side was all corroded and flat worn out. Real commercial divers don't wear a watch. They are another thing to hang up, they are easy to lose, you can't see the thing 90% of the time, and the surface radio man and dive master keep track of your time anyway.

Steve

That's odd to hear, Ernie. We got zapped a lot, sometimes pretty heavy. Lots of just tingles. But nothing bad where we had to do CPR, or where it left a mark. Just lots of cussing over the radio.

Steve

No. Control is totally topside with a knife switch. Diver sez make it hot, and the knife switch is thrown. When done, he's SUPPOSED to say make it cold so he doesn't get zapped, or the corrosion on his helmet continues. On the work we did, it was all done with a knife switch topside run by an assistant of the radio man.

Steve

I went to diving school in 1974, and worked for about a total of eight years after that. I am commenting on methods and equipment used at that time. In the ensuing years, I'm sure there's been changes and better stuff. Ernie would know about that. So, my comments are just on the way we did things back then, and with the new stuff, someone who has used it recently should comment. Autodark for even above water welding wasn't even a figment of someone's imagination at that time.

For all other things I say that are wrong, please consider that they are just in error, and not really wrong.

Steve ;'-)

"SteveB" wrote: Control is totally topside with a knife switch. Diver sez make it hot,

^^^^^^^^^^^^^^^^^^^^^^^^ I can think of two reasons for using a knife switch: 1.) It is possible to see at a glance whether it is on or off. 2.) The switch carries the full welding current.

Am I on the right track?

It's for safety. It removes any chance of the welder doing something stupid, or say a cable gets cut or mashed or pinched, and goes to ground. Or the diver narcs out or is kayoed. It takes control of the on/off out of the hands of the diver.

Steve