Comprehensive analysis and evaluation of the structural damage and servicelife state for 12 Cr1MoV steam conduit from boiler of unit no4 in Jinzhushan Power Plant have been carried out by using many methods

such as analysis of chemical composition

elongation test under normal atmosphere temperature

metallurgical and electronic microscopic analysis

creep damage observation

endurance strength test under high temperature etc.. Test results show that the spheroidizing degree of metallurgical structure appeared at the elbow bent of said steam conduit after operation of 151609h to be serious

the creep damage approaches 3rd degree

and obvious reduction of tensile strength under normal atmosphere temperature and of endurance strenoth under high temperature. In continuous utilization of said steam conduit

supervision should be strengthened for its elbow bent

ensuring safe operation of the steam conduit.