In order to analyze the causes of leakage of high temperature superheater tubes in an ultra-supercritical 1 000 MW unit boiler

macro-morphology examination

physical and chemical properties test

microstructure analysis and material hardness test were carried out on the samples collected on site. The test results show that

the leak reason is that the oxide scales on the pipeline peel off

leading to blockage of the pipeline and local overheating. Thus

a preventive steam purging method using high and low pressure bypass is proposed to realize controlled peeling and orderly discharge of oxide scales on boiler steam pipes and ensure the safety of the later operation of the unit. The practical application effect of the oxide scale stripping and purging method is good

which can provide reference for similar units.