engleski

An Ultrasound Subwavelength NDE Device for Detection of Subsurface Micrometer Defects Formation in Superheated Steam Systems

Small, micrometre sized, defects could be an indisputable indication of a development start of a larger damage in superheated steam systems. A descriptive example of such process is the creep damage in superheated steam pipelines – its early stage is manifested in very small, micrometre size, voids in the steel structure. Those defects are two orders of magnitude smaller than the defects that are usually the subject of classic ultrasound, non-destructive examination, NDE tools during inspections and thus present a very difficult NDE task. On the other hand, if not monitored, the creep damage in its later stages is limiting the operational life of pressurized superheated components in thermal and nuclear power plants and other similar systems, and could even lead to catastrophic failures of such systems. To detect such early stage defects, which form below surface of the material, one has to go to subwavelength ultrasound NDE techniques that include high-frequency ultrasound transducers and advanced signal analysis. A highly sensitive ultrasound subwavelength NDE testing device for detection of micrometre size damage in stainless steel was developed. Both laboratory and field tests results of the device performance are shown and critical challenges met during the development of the system are presented and discussed.

NDT, NDE, non-destructive testing, creep damage, subwavelength defects, ultrasound

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