Evaluation of Steam Turbine Blades Surface Cracks Detectability by Nondestructive Methods

Abstract

Paper describes methods suitable for crack detection on low pressure steam turbine blades, not including the blade root. These cracks, which are initiated in the corrosion pitting, can cause serious damage to the steam turbine blade leading to its breakaway. Therefore, the detection of these cracks on the early stages of blade fracture is very important. Several methods for detecting of surface cracks (ultrasonic Rayleigh waves, eddy current with flexible array probe, etc.) has been tested on artificial flaws, which were manufactured into turbine blades. The comparison of all these methods is described as well as the evaluation of their advantages and disadvantages. Simulations of ultrasonic testing is also presented in this paper.

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“…At present, Vesela´et al 2 has made a series of summaries on the methods of detecting steam turbine blades, and concluded that ultrasonic crack detection is a better detection technology, but the premise of the conclusion is to disassemble the turbine blades. We are studying two steam turbine blades of 517EWT48 and 117EWT10 provided by Shanghai Electric Power Generation Equipment Co., Ltd., as shown in Figure 2.…”