Thank you for your concern regarding the use of POR-15. Yes, it's designed
to be applied to a rusty surface, however, it's also rust resistant,
corrosion resistant, and doesn't chip or crack. Which makes applying it to
a propane tank that rides underneath a vehicle very practical. The amount
of abuse the tank goes through under there requires a restoration be done
with the thought that this kind of abuse will contunue. Why not give your
LP tank some love and protection like a couple coats of POR-15. Just
because I knocked most the rust off doesn't mean I'm doing the tank any
harm by give it a nice suit of armor!!

Other notes:I plan to get the interior of the tank scoped before I
purchased any new hardware for it. Just to make sure it all looks good in
there.