Through a series of nondestructive methods

such as macroscopic inspection

ultrasonic flaw detection

magnetic particle test

metallographic examination

hardness measurement

and thickness measurement of internal oxide layer and metallic layer etc.

the material state and creep residual life of steam conduit for boilers in one power plant have been evaluated.The results of evaluation show that the selectively inspected elbows of seven steam conduits are aged to a certain extent

but the hardness is normal

and there isn't obvious performance degradation.Under current operating conditions

the steam conduits can safely serve more than two overhaul periods.