Environmental Engineering Reference
In-Depth Information
P
, %
a
, mm
5.9
Dependence of the detectability of defects in inspection using
different techniques, on the length of the defect: 1) method No. 1
as used by developers; 2) method No. 2 as used by developers; 3)
method No. 2 as used by nuclear power plants; 4) inspection in 1988
in a nuclear power plant; 5) inspection in 1991 in a nuclear power.
Comparison of different inspection methods
In this case, the results of inspection carried out by different methods are
plotted in the same coordinate system: the probability of defect detection
- the defect size. Figure 5.9 shows the results obtained by five different
inspection methods, and the curves 1-3 were obtained using test samples
from a pipeline with a diameter of 55 mm made of austenitic steel. The test
sample of the piping DN 500 was made of standard welding technology
for shells of pipes made of 08Kh18N9T steel with EA-400/10T welding
electrodes 4 mm in diameter (Fig. 5.8).
Curve 1 (see Fig. 5.9) was obtained by the method developed by NPO
NIKIMT. The weld was inspected out by the dual-frequency method in a
ADMT-21UB flaw detector with a converter with the prism angle of 50
o
at frequencies of 1.2-1.8 MHz and with a transducer with the prism angle
of 40
o
at the same frequencies. Sensitivity setting for inspection with the
converter with the prism angle of 50
o
was performed in a 3.5; 2.2 mm
Table 5.2
Smallest detectable level in inspection with a tranducer
with the prism angle of 50
o
Depth mm
Point defects
Defect length
0-10
Signal from the notch 2 dB
Signal from notch 4 dB
Direct beam: the signal from the notch
8 dB
Reflected beam: the signal from
the notch 2 dB
10-24
24-34
Signal from the notch 8 dB
Signal from the notch 2 dB
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