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Ant428
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Good afternoon,

I had to cut a booster heater in two pieces in order to fix the internals. It is a water heater on a commercial dish machine. It heats the water to over 180 degrees and has house water pressure coming to it. I have the tank ready to weld, with a purge hose set up. My question is, would you leave a gap on 1/16 wall stainless? Should I just butt it up and fuse it together with no filler? I want to make sure I get good penetration.

Anthony Salvate
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Poland308
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Leave a gap SS shrinks enough it will pull it closed as you work your way around.
I have more questions than answers

Josh
Ant428
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Poland308 wrote:Leave a gap SS shrinks enough it will pull it closed as you work your way around.
Well I wish I read this before welding this up. It pulled so much that it began to implode on itself since the metal had nowhere to go. It looks like a little divot. Next time I'll leave a gap. Will this hurt the integrity of the joint? I got penetration.
Poland308
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With stainless it leaves stress in the metal. Since this application will probably see a lot of heat cycles then eventually it will get stress cracks starting in the haz. However, your already extending the life of the unit, so then there still ahead of the game.
I have more questions than answers

Josh
Ant428
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Poland308 wrote:With stainless it leaves stress in the metal. Since this application will probably see a lot of heat cycles then eventually it will get stress cracks starting in the haz. However, your already extending the life of the unit, so then there still ahead of the game.
So it may begin to leak a little? It won't blow open right?
Poland308
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Over time It will develop small stress cracks that will weep. But city water pressure is usually around 50-75 psi. Sometimes up around 90, but that’s rare. So no catastrophic failures. If they leave it on continuous and don’t shut it off to cool it will reduce the heat cycles. I think most machines only boost heat during part of there program so that’s probably not an option.
I have more questions than answers

Josh
Ant428
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Poland308 wrote:Over time It will develop small stress cracks that will weep. But city water pressure is usually around 50-75 psi. Sometimes up around 90, but that’s rare. So no catastrophic failures. If they leave it on continuous and don’t shut it off to cool it will reduce the heat cycles. I think most machines only boost heat during part of there program so that’s probably not an option.
It actually only gets water pressure when the rinse cycle goes on. And the booster is maintaining heat all day. So it will only go through a cooking cycle 2 tines a day maybe.
I couldn't get a great looking bead because I don't have a dual flowmeter, so I put a Y after my regulator. Most of the gas went to the purge and I struggled with getting great coverage for my bead. It just looked a bit gray but still ok. I weaved afterwards which was probably a mistake, but it made it look nice. I only needed 35 amps. Stainless really seems to require much less heat than mild steel.
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noddybrian
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Looks pretty good from here - keeping heat at bay on thin stainless is always a challenge - couple of thoughts - if I were doing it I would roll a narrow band say 1" wide into a ring & tack it into one half of the tank a little at a time with plenty of clamps & use this as a backing strip for the joint plus it doubles as an alignment band for the joint when the other half is fitted - it would give a bit more thickness at the joint allowing for a slight root gap & reduce the need for purge if done with care on heat input - with regard to purge it can be done easily with a single regulator - just unscrew the flow valve / floating ball fit a valved Y & connect the purge to one side - floating ball to the other - adjust the purge flow by ear ( or buy a second floating ball ) & use original to set torch flow - or like most of us old folks use the ear for both !

Typical Valved Y fitting
Typical Valved Y fitting
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Ant428
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noddybrian wrote:Looks pretty good from here - keeping heat at bay on thin stainless is always a challenge - couple of thoughts - if I were doing it I would roll a narrow band say 1" wide into a ring & tack it into one half of the tank a little at a time with plenty of clamps & use this as a backing strip for the joint plus it doubles as an alignment band for the joint when the other half is fitted - it would give a bit more thickness at the joint allowing for a slight root gap & reduce the need for purge if done with care on heat input - with regard to purge it can be done easily with a single regulator - just unscrew the flow valve / floating ball fit a valved Y & connect the purge to one side - floating ball to the other - adjust the purge flow by ear ( or buy a second floating ball ) & use original to set torch flow - or like most of us old folks use the ear for both !

oxygen Y fitting.jpg
The sleeve is a great idea! I could have just made a ring to fit right in there and not purge. I suppose most would have used pulse to keep the heat at bay.
As far as the Y, I used one, maybe not the way described. I had it after the regulator. But all the gas was going to the purge and not the torch. Maybe i could have added a bit of restriction. I think I'm going to buy a dual flow regulator. Miller has one for $180. May be worth getting the next time I need to purge.
I hooked the booster up and there are no leaks, so that's good! Thanks for the reply!
Poland308
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Doesn’t look bad at all. SS does kinda soak up on the heat. But like a sponge it can only take so much. It’s not uncommon to have to turn down your amps as the part warms up. I use a single regulator with two flow ball needle valves to keep the flow where I want it.
I have more questions than answers

Josh
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Ant428 wrote: I think I'm going to buy a dual flow regulator. Miller has one for $180. May be worth getting the next time I need to purge.
I hooked the booster up and there are no leaks, so that's good! Thanks for the reply!
USAWeld has a dual flowmeter for ~$100, I've used it and it works well.
Richard
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Ant428
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LtBadd wrote:
Ant428 wrote: I think I'm going to buy a dual flow regulator. Miller has one for $180. May be worth getting the next time I need to purge.
I hooked the booster up and there are no leaks, so that's good! Thanks for the reply!
USAWeld has a dual flowmeter for ~$100, I've used it and it works well.
Nice, Ill take a look at that. I get worried about buying a cheap regulator. It does have to regulate 2000psi. How does this one feel? Heavy ? Solid? I saw a good review on youtube .
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