Environmental Engineering Reference
In-Depth Information
inspection of the product N det prod .
Residual defects are divided into the reliable part χ ≤ χ d and the
probabilistic part χ > χ d .
χ d is determined from the equation
c
max
ϕc c=
(
) d
1,
c
d
where χ max is the maximum possible size of the defects in this product.
The probabilistic parts of the initial and residual defects are plotted
on the same graph which shows the regulatory curve of the status of the
product.
The curve of probabilistic parts of the initial (hereinafter initial
defectiveness) and residual defects (hereinafter - the curve of residual
defectiveness) of the product is compared with the regulatory curves of
the status of the product.
Analysis of the curve of the initial defectiveness indicates the state in
which the product was before repair (removal) of the detected defects:
1) The first variant of the position of the curves. If the curves of the
initial and residual defects are below the regulatory curve, then this is
evidence of the satisfactory state of the product, and such a product (or
products of this type) is not required to undergo inspection or the extent
of inspection in the future can be minimised (Fig. 6.9);
2) The second variant of position of the curves. If the curve of initial
defectiveness lies above the regulatory curve and the curve of residual
defectiveness is below the regulatory curve, then the product after repair
and removal of identified defects is in satisfactory condition and may
be used. However, it must be periodically inspected and defects must
be removed (Fig. 6.10). The position of the curves indicates satisfactory
quality, reliability and safety of the product;
3) The third variant of position of the curves (Fig. 6.11). If the curves
2 and 3 of the residual and initial defectivness are positioned above the
regulatory curve 1, this product requires additional inspection and repair
defects.
Thus, if the curves are arranged as described in the first and second
variants, they are restricted by the NDI and repairs which were already
carried out, and if the third variant applies, the product should be again
inspected and repairs should be carried out in accordance with the new
inspection results.
This method can be applied to groups of similar products with
approximately the same geometrical dimensions, material, manufacturing
method and operating conditions.
The second variant may be described as follows. One defines the product
or group of similar products of appropriate quality, reliability and safety
of which shall be provided.
￿ ￿ ￿ ￿ ￿
Search WWH ::




Custom Search