Environmental Engineering Reference
In-Depth Information
a rep
4.3 Correction of the depth distribution of defects in inspection
of metal in the initial period of operation of the structure.
1 - dependence of the probability of detection on crack depth;
2 - distribution of the depth of the detected cracks prior to repair;
3 - irregular distribution of defects based on the likelihood of
their non-detection; 4 - the distribution with defect repair taken
into account; 5 - projected distribution of the normalized crack
depth after repair.
In subsequent stages of operation inspection of metal also identifies
defects which are then repaired in accordance with the efficiency of
inspection devices. However, the following situation arises as a result of
calculation analysis in subsequent stages taking into account the results of
analysis at the initial stage of operation:
- the initial distribution of the size and number of calculated defects
is the predicted distribution of the size and number of calculated defects
identified at the initial stage of operation and adjusted due to the nucleation
of new defects and corrosion fatigue growth of defects at the time of
operational inspection p d [ a i l )], p d [ l i l )], v i d l );
- projected distributions of the size and number of defects calculated
after inspecting and repairing the metal are determined based on the
application procedure for adjusting the projected distributions of the size
and number of defects prior to inspecting the metal.
If it is assumed that inspection of metal starts at time τ l , the projected
depth distributions of calculated defects after testing of metal and repairs
are defined as follows
￿ ￿ ￿ ￿ ￿
i
pa
()
t
d
l
tt
i
i
i
pa
(
+
) =
at
a a
;
d
l
ins
per
C
pa
i
i
()
t−
p a Pa
( )
i
×
i
()
t
d
l
ins
d
l
t Dt
i
i
i
pa
(
+
) =
at
a a
,
d
l
ins
per
C
i
i
i
a
a
per
per
{
}
i
i
i
i
i
[4.42]
C pa
=
()
t+
pa
()
pa pa
t−
( )
×
()
a
t
.
i
d
l
d
l
ins
d
l
0
0
 
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