In centrifugal compressors the rotor is the component most subject to physical and chemical wear. If the surface of bearing area is affected by scoring or denting, generally caused by dirt in the lubricating oil or sudden dynamic instability , it can be repaired if the surface is made with chromium plating, weld-repair and in some cases application of an interference fitted, specially treated alloy metal sleeve. These solutions include turning and grinding to restore the nominal diameter of the bearing land. If the seal area bushing is affected by scoring and/or corrosion, which can be caused by friction due to contact with the seals or change in the gas conditions, the bushing must be replaced by shrink fitting. Presence of fretting which is a type of erosion, classified as a form of adhesive wear, takes place when the surfaces of the cone and the mating coupling are subject to relative motion of a small amplitude in the region of hundredths of millimeters. The damage it causes implies the formation of surface pits or removal of material through wear with possible crack initiation. This can be cured by repairing the weld and the surface grinding to nominal diameter