In accordance with the layout features of a boiler unit at Lazidan Power Plant in Armenia, boiler steam-plus-oxygen technology instead of the traditional chemical washing plus ignition purging technique was introduced for the purging and passivation of the steam-water system of the boiler unit. Good results have been achieved in the practical use of the abovementioned technology with energy loss being reduced and pollution of environment by chemicals avoided. Through a comparison of the technology under discussion with traditional ones the authors describe the theoretical basis of the recommended washing and passivation techniques. The latter are worthy of a wider popularization and can serve as additional reference data und information for analogous domestic techniques.