I think I understand what you are trying to do now. You need to calculate an energy balance equation like this..
Energy input from electric sources = Mechanical energy output + Increase in energy stored in electric field + Energy converted into heat
You also need to know the permeability value of your iron pipe and coil's dimensions in order to properly calculate for coil's inductance. The number of turns can be approximated from calculated inductance... Well, that's my two cents..It has been a long time since I studied 'Electromechanical Energy Conversion'. You may find this link a good starting point...http://ee.sharif.edu/~machine2/texts/Electric%20Machines%20-%20Fitzgerald%20PDF/electric%20machine%20Ch03.pdf