Welding and water

[Odd Job Welding]

Hi All - I just spent about 2 hours welding a stainless steel tank that was leaking - All of 10 cm ( 4 inches). The tank normally contains methylated spirit. It was flushed a couple of times with water and purged. The area where it leaked held a small amount of water that I could not get out. So I welded a wet seam. The only way I could do it was form a puddle on a dry area and then migrate to the wet seam and kinda drive the water in front of the puddle out of the seam. Its a pain in the behind as the arc is unstable. If I have to do something like that again I would like to know if any of you have a better way of welding a wet seam. I was using tig as the tank is thin walled. The welding was done upside down and stainless steel stick welding was not really an option due to the thin wall of the tank - I was worried about blowing a hole and creating more problems. Nonetheless,would spot welding with stick work in this scenario? Thanks for any input.

[WookieWelding]

a lil preheat to dry "it"the joint out ???

[Odd Job Welding]

The section of tank held too much to preheat. Wet joints are not really a prob lem as the welding process itself generally pre-heats enough to drive resident moisture out. I am talking about the situation where the joint leak has a constant supply of water. The tank in question is part of a structure and cannot be removed.

[Odd Job Welding]

Thanks for the seedy response. The section of tank held too much water to preheat and evaporate. Wet joints are not really a problem as the welding process itself generally pre-heats enough to drive resident moisture out. I am talking about the situation where the joint leak has a constant supply of water. The tank in question is part of a structure and cannot be removed and as always the customer is hopping up and down and shouting about production. I have a very good relationship with the customer and I got the job done. I was just wondering if there is a faster way of doing it next time round

[Insaneride]

Could you use a piece of bread? The bread soaks up the xcess water and purges when you refill with methylated spirit. Just a thought.

[Odd Job Welding]

Thanks for the bread idea. I was thinking of putty or some similar substance, but in the past when I tig welded into putty the results were not pretty. I never thought of bread and I will try it next time. I find that as long as I can get a dry spot for a second or two I can start the puddle and get going. Mayhaps bread will do it. Thanks again

[Oldiron2]

Close up all the openings but one (not counting the seam being welded) and apply a vacuum to it. Entering air or TIG gas will 'blow' the water away from the inside of the joint somewhat, depending on the degree of leakage. A shop vacuum should work OK.

If you could put a strong vacuum on (as from a good, high capacity vacuum pump), it would allow the water to boil at a much lower temperature and with less preheat. That, together with the leakage, should do some good. Just don't collapse the tank; if it's thin, this isn't safe with either vac. source.

[Insaneride]

Originally Posted by Odd Job Welding

Thanks for the bread idea. I was thinking of putty or some similar substance, but in the past when I tig welded into putty the results were not pretty. I never thought of bread and I will try it next time. I find that as long as I can get a dry spot for a second or two I can start the puddle and get going. Mayhaps bread will do it. Thanks again

Your welcome for the bread idea. It works but it sounds like your dealing with alot of water. Bread couldnt hurt and its food grade. Ive used this old timer trick for sweating copper plumbing. Theres a dissovable egg shaped stuf that you can buy at plumber supply house; its intended for the same thing but that would waste time/gas going to get it and then you would probably lose or destroy the leftovers before using it all so, use bread.

[Dualie]

A strong high capacity vacuum pump could also collapse the tank like a beer can under a fat mans foot. I had to watch a training safety video where they collapsed a rail car with a fairly insignificant amount of vacuum

[jpump5]

X2 on the vacuum warning.Seen the railcar thing first hand.
Guy starts to unload car with vacuum hose at bottom
and forgets to open hatch at top.

[Insaneride]

Vacuum or laminar flow would distrupt gas flow(Argon,CO2, He. Xe Ne,etc)Wouldnt it? Nev er mind

[LarryO]

Originally Posted by Insaneride

Vacuum or laminar flow would distrupt gas flow(Argon,CO2, He. Xe Ne,etc)Wouldnt it? Nev er mind

You should keep off the keyboard while drinking.

[Insaneride]

My original idea for evacuating a vessel of some type is; use air vacuum whatever to get the bulk, then, pour in 90% alchohol, then ignite it. Stand back for safety officials. Then use bread or the safe chemical the local plumber supply carries. Then: shut up and weld!

[Insaneride]

OK BYE Angel Larry)

[dougspair]

Without seeing a picture, it's a tough call, but I've had similar fiascos with Stainless and Aluminum. Sometimes I drilled a tiny (1/16th) or so hole at the lowest point, did the repairs, then welded up the hole I drilled. Purging the inside with a constant flow of argon might be helpful.