Your bolt holes on the equipment alone are going to be about 1/16" oversized to begin with.

That said, I also support Dr. Becht's call for a more rigourous analysis. The structural engineers should be able to give you some guidance on stiffness of the support structure and a quick run with FE/Pipe Nozzle Pro will give you some stiffness values for the two nozzle/shell interfaces.

For a short a run as you've got an the temperatures you're looking at, I wouldn't be surprised if your loads drop dramatically.