this. it'll be fine as long as it's clean and free of gunk before you start. IF it makes you feel any better you can spray some starsan from a spray bottle into the outlet of the valve before you open it.
When I got my 8 gallon kettle from More Beer the instructions said that their testing proved that the ball valve would not get hot enough to sterilize. They recommended taking it off putting it in a pot of boiling water before each brew.
that's interesting.. when I was cooking with propane I was melting the handle on the ball valve, it was definitely getting hot enough to be sanitary. Now, with the electric system I have to circulate through the pump and plate chiller anyways - so it gets up to boiling for 15 minutes during that.