To maintain as-designed alignments

To maintain as-designed alignments in rotor trains, it is important to have the rim and the face runouts within the design tolerances. However, in addition to the coupling gap/displacement alignments, there is another element that helps maintaining close tolerances in the coupling joint is the “coupling bolt.” After the shafts and the coupling halves are aligned to recommended tolerances, the coupling holes are line-reamed or honed to receive the bolts that keep the two coupling halves aligned together as one solid joint. Bolts are prestretched, torqued, and tightened to the two outer end faces of the couplings by nuts for a tighter fit of the coupling halves