[taiwanluthiers]

Has anyone personally done it before? I mean in welding we want to keep water OUT of it, and so it seems like underwater welding shouldn't be possible right? I doubt I'd ever do it simply because I can't swim let alone scuba dive, and so the only real possibility for me to weld anything underwater is say under knee deep water and it can't be taken out of the water, in a submerged tank or whatever.

How is it done? I'm guessing it's done with stick, can those stick be bought at all? And I'm guessing the welder itself has special rating for underwater use? Due to risk of shock and all that...

[tweake]

very specialized skill set.
i think jody has a podcast on it, interview with one of the guys who does it. the interesting comment was the diving is the hardest part. they would rather take a diver and teach them to weld than teach a welder how to dive.
one very dangerous job.

[taiwanluthiers]

So what do they use to weld it, special electrodes, and presumably only stick welding?

I can only ever see myself in the distant future weld stuff sitting under water but not require scuba gears, like in a shallow knee deep pond for example. I wouldn't use a normal welder for the job anyways, I'm sure special welder is used for this that is designed for the job.

Maybe those same stick is useful for say welding outside in the rain because the job just gotta get done.

[tweake]

So what do they use to weld it, special electrodes, and presumably only stick welding?

I can only ever see myself in the distant future weld stuff sitting under water but not require scuba gears, like in a shallow knee deep pond for example. I wouldn't use a normal welder for the job anyways, I'm sure special welder is used for this that is designed for the job.

Maybe those same stick is useful for say welding outside in the rain because the job just gotta get done.

afaik special electrode, but i've never looked into it because its something your not going to do.
if its raining you put a cover or umbrella over you and the work. pump the water out if need be.

one of the problems with water and welding is hydrogen embrittlement. that makes welds crack and fail, which is why we have low hydrogen electrodes for code work. i have no idea how underwater welding deals with that.

[taiwanluthiers]

My guess is, either the stick has special composition to deal with it, or the flux somehow keeps water out. Either that or the structure is designed with some allowance for brittle welds?

I seen someone talk about using hydrogen torch for welding and I told him the last thing you want in welding is any water, and hydrogen torch produces water.

[Arno]

The flux on underwater rods produces a shielding gas that also pushes any water away when the arc is going and the extreme temperature of the arc itself vapourises the water rapidly.. Pretty similar to a normal rod that provides a shielding gas from the oxygen in the air.

Striking the arc is the most uncomfortable though as until the current has an established path to the work piece it will try to find other ways and the diver is one of them, giving them electric shocks. Also you need to always keep any extremities away from the path between the stinger and the work piece as that's where the majority of the current flows. Salt water is of course the most problematic here..

Hydrogen embrittlement is a thing, but mostly an issue on high strength alloyed steels. Mild steel types, often used in (large) construction, don't suffer much from this.

As such you can weld with a hydrogen fueled torch just fine. Really not that much different from welding with acetylene (C2H2) which will also produce water anyway.

There have been fairly esoteric welding processes that used hydrogen in the past like atomic hydrogen arc welding which uses it more like a plasma: https://www.youtube.com/watch?v=uZwYMyHlWXk

Bye, Arno.

[tweake]

thank you arno. always good info.