CADWorxP&ID tab: Size_Spec > Main Assign 
Size / Spec toolbar: Main Assign
P&ID menu: Accessory > Size > Main Assign
Command line: MAINASSIGN
Assigns the main size, set using Size Set 
, to the selected components. This is useful when components are placed on a new drawing
before a size is set. When components already have a size, Main Assign can reassign them to a new main size.