difficult repair of stainless tank

Hello All,
I have a difficult repair problem, It is a tank in a Slushie machine, it is made of .035" stainless, and I can
only get to one side of the tank. The hole is small, about 3/32" in diameter, it is from a rub spot inside the tank (the source can be fixed).
The bad part about this is, the tank has refrigeration coils around it (I don't know exactly where they run) it also has foamed in place insulation over this, and a stainless shell over this.
I don't mind burning some of the insulation, I would like to do this from the inside of the tank. What ever I do has to be compatable with food service, the mix in the tank is sugar water and citric acid.
My thoughts are using a Micro-torch and silver braze. Epoxie would be great, but I don't know if they make food grade, and I don't know if it would hold up. TIG was a thought, but I would have to cut open the shell, and remove insulation.
What do you guys think ? What silver braze has the lowest melting point ?
Any better ideas are welcome.
Thanks Dave J.
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The simplest fix I can think of is a small circle of 0.035" SS that will cover the hole. Bond it in place using pure tin solder and zinc chloride flux. Pure tin solder is food service grade. The temp should be low enough not to burn away too much foam or affect the coolant lines. Try it on some test pieces to get the heat right.
A small propane torch is plenty hot enough to do it.
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Pure tin may be food service grade, but the zinc chloride flux sure isn't. It will be necessary to remove all traces of it before putting the unit back in service.
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I use a product called SIL-TIN made by the comapny called HI-ALLOY it comes wit its own flux (liquid) and melting temp. is 430 degrees F a small micro-torch will do just fine , sometime I use a heat gun when I use it on thin material. It confoms to pure food law. as the spec sheet states it. does not contain lead, zinc, or cadmium tensile strenght on stainless = up to 25000 PSI and 14000 PSI on copper alloys.
it is good stuff.
wrote:

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