Environmental Engineering Reference
In-Depth Information
cr
add
5.45
Curves of residual defectiveness after inspection nd repair
of detected defects 1 and after more detailed inspection and repair
of defected defects 2.
a
a
max
max
[
]
[
]
∫
−
n
S
∫
−
n
Aa
exp
−α −
(
a a da
)
=
1;
N
Aa
=
exp
−α −
(
a a da
)
;
0
0
res.rel
[ ]
a
a
d
d.ser
a
max
[
]
S
∫
−
n
N
=
Aa
exp
−α −
(
a a da
)
.
res.safe
0
a
cr
In this case
a
mas
=
s
, where
s
is the wall thickness of the pipe. The results
of the solutions are presented in Fig. 5.45 as curve 1. The defects permitted
in service operate and critical size defects marked accordingly as [
a
] and
a
cr
.
Finally,
a
d
= 14 mm,
R
= 1-1 = 0,
S
= 1-0.55=0.45.
Since the values of reliability and safety for the characteristics of the
residual defectiveness in accordance with curve 1 are unacceptably low, the
product was rejected and sent back for further processing. The product was
the subjected to repeated inspection and repair and the results are described
by curve 2. In this case, reliability was
R
= 1-
N
res.rel
= 1 - 0.1 = 0.9
and safety
S = 1 -
N
res.safe
= 1 - 0.001 = 0.999.
On the basis of the results the product was then admitted into service.
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