Based on extensive investigation and tactings

this paper presents a study Of the remainins lives of 12CrMo

15CrMo

15Cr1Mo1V and 10CrMo910 steam mains used in power plants with peak-loading

which were effeCted by creep-fatigueinteraction.Testings of creeplatteue interaction were conducted at hish temperatures and under controlled load conditionswith a dwell-time.Metullurgical examinations were carried out top to determine the extent of creep and fatigue demapeand the deterioration of microstructure. As a direct result of this study

more reasonable procedures of unit start-up andshut-down are propased and some failure criterions suasested.