From what i have read the machined locknut for the keggle and cooler kits is a special machined item made by the keggle kit people. NOT
Locknut, Pipe Size 1/2 In, NPT Connection, Material of Construction Red Brass, Pressure 125 PSI, Temp Range -20 To 400 Deg F, Standards ANSI B1.20.1 Specifications APPROVED VENDOR
1VFN9 Today $1.93
Grainger has it as well as all the stainless pipe fittings to do it for about $12.00, minus the, orings and washers which you have to buy in bulk and the valve they don't sell.