It depends on to what extent ...

It depends on to what extent you can tolerate salt passage raise due to working at higher temperature bringing about higher conductivity of your product. Plus, the permissible temperature which membranes can work at depends on the pressure drop created through elements. The lower pressure drop through a pressure vessel, the higher temperature membrane elements can resist. Membrane elements have experienced CIP at about 55C while pressure drop through pressure vessel was about 2 bar.