Curtis Superior Valves are designed for installation in a standard NPT port for NPT threaded valves or an AND-10050 stlye port for UNF threaded valves. Use a sealant on NPT threaded valves or a fuel resistant o-ring of the proper size for UNF threaded valves. Refer to aircraft manufacturers torque specifications for the aircraft in which it is being used. Curtis Superior Valves require no special maintenance. Keep them reasonably clean and replace according to the prescribed synthetic rubber maintenance schedule for the aircraft in which they are used or 10 year usable life per Curtis Superior Valve whichever occurs first. Curtis Superior Valves cannot be OVERHAULED. Replace the entire valve per the maintenance schedule of the aircraft in which it is used or usable life per Curtis Superior Valve should it begin to leak.