This work investigates possible options for replacing the main separator of steam power boilers to ensure their maximal service life. Separators of drum-type boilers are reviewed in terms of their advantages and disadvantages. An analysis of two steels – WB36 and 16GNMA – is carried out by comparing their performance characteristics, chemical composition, and welding procedures. Possible technical solutions for replacing overaged drum boilers are analyzed from the technical and economic perspectives. Three options were selected for replacing the separator: a similar drum made of imported grade WB36 steel; an alternative option with a small drum and a bank of off-mounted cyclones; a drumless option based on a multi-stage evaporation cycle and a bank of cyclones. The materials currently used in separators, i.e., 16GNM and 16GNMA, are compared with imported WB36 steel. It was found that each option had its own advantages and disadvantages, which should be analyzed according to the following parameters: weight and dimensions; assumed need in lifting equipment; hydraulic losses; assumed changes in automatic boiler equipment; relative costs associated with designing, analysis, and risk management. Therefore, the presented recommendations for selecting a drum replacement option are essential for extending the service life and ensuring the reliable and safe operation of boiler equipment.