Through macroscopic inspection as well as microstructure and energy spectrum analysis for the tube-wall of bursted tubes on low-temperature reheater of a boiler in one power plant

it shows that the causes leading to tube-burst on low-temperature rehater is related to the serious tube-wall thickness reduction resulted from oxygen corrosion due to unsuitable boiler shutdown conservation.For this

the oxygen addition has to be stopped before 4~12 hours of the unit shutdown

and enlarging the ammonia injection after polishing treatment of the condensate

making the pH value of feed-water to be enhanced to 9.1~9.4

moreover

the boiler has to be dried out by using the residual heat of blow-off water from the hot furnace

so as to effectively reduce the demage of oxygen corrosion onto the equipments.