I'm not out of stock on silicone. Honestly I wouldn't use the vinyl stuff. If you had to, 3/4" ID would make it over the threads. 1/2" NPT threads are about .84". You'll still need to heat it with hot water but the main thing is that silicone seems to fill in the valleys of the threads and I don't know if pvc will do that.
Welcome to BrewHardware.com. I love you.
New 100% Stainless Steel Heating Elements are IN! ULWD 5500w Ripple, 2000w, 1500w, etc
Chugger Pumps, Pump Kits, Camlocks, Sightglasses, Clear USA made Silicone Tubing, RIMS, Electric Install Parts, etc.