African Fusion March 2015

No Type #1 Crack

Actual

Measured Deviation

0.30 0.40 0.42 0.36 0.71 0.48

0.35 0.47 0.43 0.35 0.59 0.47

-0.05 -0.07 -0.01 0.01 0.12 0.01

#2

VLOF

#3 Crack #4 HLOF #5 Crack #6 Crack

Table 4: Flaw sizing results for specimen. Conclusion

For phased array ultrasonic testing designed for inspecting piping welds in a nuclear power plant or industrial structure, a 3.5 MHz shear wave phased array ultrasonic probe was designed and developed with 16 linear type piezoelectric elements capable of generating an ultrasonic beam at angles ranging from 35 ° to 80 ° in order to inspect small bore piping socket welds without using a wedge for high accessibility. With the aim of analysing inspection results off-line in variousmodes, a semi-automatic scanner was developed. The scanner enabled the phased array ultrasonic probe to encode its location while revolving in the circumferential direction and maintaining contact on the small bore piping. Using the developed shear wave phased array probe and a manual en- coder scanner, anexperiment involving specimenswith fatigue cracks was carried out to detect six different flaws. In conclusion, application of the inspection system de- veloped in this study to the small bore piping socket weld of a nuclear power plant is expected to reduce the inspection time. This will not only contribute to reducing the inspector’s exposure to radiation but also to improving the reliability of socket weld inspection.

Figure 7: Signal evaluation results of flawed specimen with leg length of 1:1.

Figure 8: Signal evaluation results of flawed specimen with leg length of 1:2.

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March 2015

AFRICAN FUSION