I've been buying such valves for years from Brewer's hardware, likely other brew sites may be good too. If using them on hot pans, be sure the temps are within the specs of the valves. I only use them on tanks, where the sap is cold.
At least in the ones I've bought the sealing ball that rotates to open or close the flow is some sort a manufactured material and not SS, the rest of the ball valve is SS. It is food grade however, I just don't know how much heat it can take.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.