pre-service hydrotests or in-service hydrotests [5]. Also, it
has been reported that certain types of weld defects could be
differentiated from signal analysis such as emission activity,
intensity analysis or pattern recognition. Bentley and Bees-
ley [6] reported that slag inclusions and porosity specimens
generate a significant proportion of high frequency signals,
while specimens with growing cracks give large numbers of
medium low frequency signals. Shiwa et al. [7] reported that
a sample of slag inclusions generated a high activity as a
burst type signal, and a porosity sample indicated a low
activity as a continuous type of waveform.
This paper describes the AE and subsequent RT results
conducted for checking the structural defects of a repaired
large storage tank.