| I can also attest to por15. I've used it on a repaired SS tank and it's still good after 2 years. Just make sure you follow the directions, including the temp range for etching and sealing.
Also remember to make sure the vent hose and internal lines don't get sealed during the sealling process. I used some small conical plastic pieces and jammed them into the holes to prevent this.
Good luck. | 
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