Expansion is not your problem in your system. Contraction is....try to provide a little flexibility on the route of your copper line by adding few bends and turn to absorb the movement in the line.
Based from the sketch that was provided, this looks like it is the suction side of the piping to your pump. The expansion joints will not be that much affected by the additional MOV and hot-tapped fitting but because of the additional weight that you have added to the system, it will be best to...
