A Diagnosis of Failure of a Compressor Blade

The methodology and the procedure of diagnosis of a cracked stationary blade of a compressor due to high cycle fatigue is presented. The natural frequencies of the blades and a stator row were measured and an analysis of the casing vibrations during start-up and under load conditions of the compressor was conducted in a search for the cause of the failure. Using finite element code the natural frequencies and the vibratory stresses of the stator row blades (vanes) were computed. The computed maximum vibratory stresses in the vane were concentrated in the location of the crack which originated from the welded joint. It was concluded that the welded joint requires modification.