Compressor rotor structure for turbomachinery, such as a compressor, is provided. Disclosed embodiments can benefit from sealing sleeves that may be arranged to inhibit passage onto respective hirth couplings of process fluid being processed by the compressor. The sealing sleeves may be affixed to adjoining structures (e.g., adjoining impeller bodies) by way of a slip fit connection to one of the adjoining structures and an interference fit connection with respect to the other adjoining structure, which is conducive to a user-friendly assembly of the sealing sleeves with the adjoining structures.