TIG weld that sucked

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Ever welded a container of some type that blew out the weld at the end?  You know, the heat builds up pressure, and right as you go to seal the thing up, you get molten metal on the tungsten and a hole in the weld.Well here's a twist on that.I had "developed" (that's what you call it when you set up a machine to do the welding) a pulsed TIG weld to seal a SS storage container.  This was a square butt, full penetration on 1/16" 304 tubing.  The joint was vented with some small holes at the end so the pressure wouldn't build up, and the holes simply fill as you pass over them.  This was a practice part, and the weld was fine, at least judging from the outside.I decided to try a different pulse setting, simply to change the "stack of dimes" appearance, so I proceeded to make another weld on the same can, below the first weld, right on the tube with no joint.  As soon as the weld got started, I got a beautifully perfect round hole, clear through the can.The weld pool had been sucked inside of the can.The first weld had heated, expanded, and pushed some of the internal shield gas out of the can.  When the sealed can cooled, the remaining gas inside cooled and created a vacuum relative to the outside.Never thought about it that way before.
Reply:This thread is useless without pics!!   ...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:Interesting information, as zapper said - can't see pics.John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:Originally Posted by pulserEver welded a container of some type that blew out the weld at the end?
Reply:Originally Posted by zapsterThis thread is useless without pics!!   ...zap!
Reply:i under stood the vacume you had in the chamber  and i like the web  site link even if thay take there time getting me my book's to meChuckASME Pressure Vessel welder
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