Support the expansion joint from below without bolting to the turbine nozzle. Adjust the lower support to achieve 0.01 clearance to the turbine nozzle. Insert bolts and tighten the flange properly. There will be minimal weight transfer to the turbine. When the unit heats up, there will be compressive force due to the stiffness of the bellows and thermal expansion. There will be pressure thrust during operation which can be calculated by using the actual cross sectional areas in your specific joints components. The pressure thrust during operation can be adjusted to provide uplift forces to the turbine flange. This will offset the small weight transfer. You must chose the cross-sectional area of the joint to provide the desired thrust. This is not as practical as applying forces and moments to piping systems prior to welding so that the as built condition after construction restraints are released will equal the calculated sustained forces and moments. Which by the way has been used for critical piping systems that have cold spring. Since we are attempting to minimize load transfer we should probably use a manually adjustable vertical support to minimize the transfer. This could work as well as the manually adjustable gap restraints used to withstand expansion and occasional displacements. One would need to know actual operating temperature when the occasional event occurred. Seriously, I suggest that you use springs to support your expansion joint components if they weigh that much. Oh, you could design a lighter weight model of the expansion joint or use some of the support details recently seen in this forum. Obfuscation is humor to the aged mind.