The valve is just a 10" 300lb. manually operated rising stem gate valve. I agree the largest contributor to stem friction is packing, but I'm looking for a way to reduce the operating nut friction without changing too much existing design (maybe PTFE thrust washers).
I'm trying to calculate opening/shutting torque values for a rising stem gate valve. The problem is that I can't find coefficients of friction for a monel operating nut on a bronze wear surface. Anyone have ideas for values or references?