Failure analysis and welding repair for water wall tube burst of 600MW station boiler

Through methods, such as microscope analysis, mechanical analysis, chemical analysis, metallography examination etc, the causes resulting in water wall tube bursting of 600MW station boiler have been analyzed. The result indicates this water wall tube burst is the high temperature creep fracture. The higher operating temperature, microstructure aging and high temperature strength degradation are the primarily inducement of bursting failure. In welding tube, the measures of reducing residual stress, such as lower welding heat input, reducing thickness of welding layer, assigning reasonably heat treatment power, lengthening holding time and so on, were taken. The welding repair succeeded greatly.