Amber you could also make a gasket out of a rubber innertube or whatever and a peice of ss sheet metal and put the rubber between the tank and peice of sheetmetal and bolt or rivet it over the holes. It will seal it up good. Also an option and Im not sure on the food grade aspect of it but if you look in the gardening section at lowes or HD near the pond supplies there is a rubber patch that comes in a roll like 6"x10' that sticks to just about anything. I have used it to seal up a ss pond filter tank that froze and split a few years ago and it is still working. It is all rubber on the outside with some sticky material on the inside.
2X6 deluxe Phanuef
Adding 200 more every year
27 years left of building a Hobby into a retirement time burner.