No matter what the result, there is clearly a production problem and we shouldn't need to be the one's doing the testing and investigation.
These are meant to be food grade quality and some clearly are not.
Pickling, treating, etc should not be our issue, nor should the cost of doing so.
I've had one mini keg replaced due to it not holding pressure, but unsure if my replacement is the good or bad one out of the two I have.
Guess which one has shown 'rust' marks on the silicone dip tube, poured out black when rinsed and has a metallic rusty taste to the beer if stored for a period of time?
Instead of trying to solve the problem, I think our time would be better spent working out the health implications from drinking out of these. I'm sure the seller wouldn't want a class health case against them and will take the appropriate action to rectify, but I'm more concerned about my health after using these.
Pic 1 is one mini and pics 2&3 are the other.