Krish,

There are two design principles that would help to control moment loads on a turbine nozzle, if there is sufficient space for flexible piping and the freedom to revise the piping geometry.
First, the piping supports are to be located in plan location so that the centroid, or center of gravity of the vertical support loads, is near the nozzle location. If say there are 3 supports in a triangle pattern, and the nozzle is located within the triangle, then the summation of the moment loads from the three supports will be much less, than if the 3 supports were located such that the turbine nozzle was located outside of the triangle of 3 supports. Visualize it as a table with 3 legs, the nozzle being the table and the supports being the legs. It would also help to locate supports near weights of valves, etc.
Second, the piping restraints for horizontal thermal growth could be located at neutral planes of thermal growth to match the turbine nozzle thermal movements. The neutral planes normally would be at the turbine shaft and at the anchored end of turbine casing (discharge end). If the piping is routed to cross both of the neutral planes, and a line stop restraint located at each of the neutral planes, then there will be restraint against thermal forces in those two directions. The remaining vertical thermal growth would be accomodated with spring hangers on piping with adequate flexibility. The best spring hanger locations would also apply the center of gravity principle to minimize moment loads resulting from the spring hangers.
If the piping geometry has already been fixed, or if there are limited options of revising the piping geometry, then the thermal deflections must be studied to decide where to add restraints with gaps to control the deflections, and hence the loads and moments on the turbine nozzle. The forces will probably need to be reduced to much lower than the force allowables in order to achieve the moment allowables.