Not for High Pressure Applications
Thermowell Hex Flat size = 1.063" Hex flat
The Sheath Length is measured from the back of the well to the bottom of the inside (also called "A" length), when the assembly is threaded into the well it will then be spring loaded.
Stainless Steel NUN´s are a three peice cast part that eliminates 2 of the threads as pictured above.
The Galvanized and black pipe NUN´s have 4 pipe threads that need to be sealed.