Tube-bursts of the high-temperature superheater in one powr plant had successively occurred after 50000h operation

through integrated analysis

including macroscopic structure

mechanical property

and metallurgical analyses of tube-samples from tube-burst and tube-cut sections

as well as evaluation of tube material status etc.

it is believed that the causes leading to tube-burst are related to blockage caused by falling-away of oxide skin. Then

some recommandations and measures have been put forward

such as preventing rapid startup and shutdown

suitably lengthening the time to open furnace gate after boiler shutdown

and mounting management system for monitoring the service life of boiler tubes etc..