PSI - Issue 13

Marko Katinić et al. / Procedia Structural Integrity 13 (2018) 2040 – 2047 Author name / Structural Integrity Procedia 00 (2018) 000–000

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3. Analysis of the blade failure causes 3.1. Analysis of the fracture location on the steam flow path

Fracture of the two blades occurred on the 5 th rotor wheel (Fig. 4). The blades on this wheel have constant aerofoil shape along their heights. The root of the blades is a tree type. Each blade is axially inserted into corresponding groove on the rotor wheel rim. These blades are tied at the ends into packs (7 and 9 blades) by means of strip banding. It is evident that this is the fracture of two adjacent blades. It was found that these are two end blades of the adjacent packages. Fracture occurred in the root of the blades, the place where the highest stress were.

Fig. 4. Fracture surface of the rotor blade roots – 5 th rotor wheel

Fig. 3. Fracture surface of the rotor blade roots – 5 th rotor wheel

Fig. 5 Steam expansion h-s diagram - Petrokemija d.d. (2009)