boat's SS water tank repair

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Finally got the repair piece and finished up this water tank.  Somebody dropped a wrench inside it and it corroded from the inside out on the bottom.Many of the original welds also leaked (don't know how that wasn't caught when it was made) and there were also some pits in the original welds that may or may not have developed after it was made.Anyway, it doesn't leak anymore.Here's the tank.  It's upside down so all the fittings on top are underneath in the photo.Slice the leaky bottom off (blue tape was the cutting guide).New piece of SS cut, fitted and tacked.Here are some bead close ups (nothing to write home about, but they don't leak).There is some slight surface rusting on this one -- hadn't been passivated yet when the picture was taken.  All is well now (used acedic acid [strong vinegar basically] to passivate and it seems to have worked fine).This one hasn't been brushed yet.Next time -- plug welds for a rail repair (same boat). Thanks for looking.  Attached ImagesFavorite right now is a Miller Syncro 200.Tons of tools and I blame at least one of them when things don't go right.
Reply:Looks like a good repair, did you fuse or add filler? Looks like filler...but just asking. John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:Added filler.  316L 1/16" diameter.  I was really concerned about burn through on the tank because I couldn't purge it (way too big and too much trouble) so I used backing flux.  PITA for me to fix a hole with no purge (maybe I'm just not good at it but I always get califlower behind a hole fix with no purge).  That's why the welds look so cold -- I made sure I got complete fusion and watched the parts melt to seal it up, but I also added filler to soak up excess heat as I went to ensure no burn through.Anyway, when I started the welding, my hands were literally shaking a little.  Tank is worth a lot and the owner kind of gave me a break by giving me the work (I told him I never did a tank like this before -- he watched me fix some of the pits, was satisfied I wouldn't destroy it and told me to go ahead and cut the old bottom off and replace it).  He's away on vacation with his family somewhere and the last thing I wanted to have to do when he got back was tell him I wrecked his tank somehow.Luckily, everything worked out.  I even had to fix some of the original welds from when the thing was made (presumably by someone who had done it a time or two before) and mine don't leak.  Favorite right now is a Miller Syncro 200.Tons of tools and I blame at least one of them when things don't go right.
Reply:Nice job.. As long as it don't leak..That can be tough stuff to do.. Now about that wrench......zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Nice job Phila.Remember, Pretty isn't always perfect.No leaky, me likey.  - Paulhttp://all-a-cart.comWelding Cart Kits and accessories
Reply:Did that thing hold drinking water?
Reply:Thanks for the posts guys.The wrench . . . I had nothing to do with that.  That's my story and I'm sticking to it.   Actually it's pretty cool; you can see the rusted outline of the wrench in the bottom of the tank, but there was no wrench when I got it(they must have taken it out).  I'll try to get a picture of it.  It's like a fossil or something.Definitely no leaks.  I leak tested it as completely as I possibly could and that's how I found numerous leaks in existing welds.  I think the leaking in the old welds added to the original problem as it allowed salt water into the tank (tank sits down in the bilge), to speed the rust of the wrench, which lead to rust of the bottom of the tank, which . . . . The beads definitely are not pretty but I hope to improve my technique at Zap's tig school mid-August.I don't think it is for potable water (although I have to ask the owner when he gets back).  There was some pretty nasty crud accumulated in the tank (as you can see when you look in it) and I certainly would not drink anything that came out of it.  Just in case I did remove all non-fused traces of the backing flux (the rest of it is glass), but I'm going to show the guy the pitcures of the accumulated crud in there and advise that there be no drinking out of that tank.  Or tell him to have it acid washed inside or something.  Not a pretty sight in there.Favorite right now is a Miller Syncro 200.Tons of tools and I blame at least one of them when things don't go right.