Thanks. The reason I asked is that using the o-ring on the inside means the kettle is sealed around the edges of the o-ring, but water can still travel the threads. The outer o-ring is smashed between the element and kettle-wall, preventing water from leaking down the sides of the kettle, but water is still technically touching that stock outer o-ring, which isn't technically "food safe". The surface area it touches is very low, just saying though.
I'm told that silicone and teflon are basically inert up to their melting points, which are not exceeded by a boil.
On my mash tun (a cooler) I used baby-bottle nipple as the inner gasket and a SS washer behind that, followed by the locknut. This gave me a hard press seal and I used teflon tape on the threads. No leaks and a firm seal. I kinda don't want the element to rotate at all and finger-tightening with inner o-ring seems like it would give the element some play.
