GE SpotChecker, Operating Manual

Page: 61 / 98

Example:
The Evaluation Assistance is based on the following
calculation of sound paths:
2 × total plate thickness × number of bw echoes
If the total plate thickness is 3.46 mm, as is the case
in the example shown, and the number of backwall
echoes (above the set evaluation threshold 10 %
screen height) is 6, the following calculation results:
2 × 3.46 × 6 = 41.52
The calculated sound path falls into the range from
35.7 to 60 mm in the table
fi led, i.e. the results “stick
weld” or “bad-through welding” would match the val-
ues. However, as intermediate echoes (
fl aw echoes)
between the backwall echo sequence likewise exceed
the evaluation threshold, the left result column (“with
FE”) applies in this case. The indicated result is con-
sequently “stick weld”.
H
Note:
Double evaluations or non-evaluation (symbol: evalu-
ation not possible) can occur if the evaluation ranges
overlap. We therefore recommend that the ranges be
set so that no overlapping occurs. Range gaps are un-
acceptable.
Evaluation Assistance III
The Evaluation Assistance III is likewise applicable to
two- and three-plate inspections (total thickness min.
1 mm, max. 12 mm). Any chosen inspection criteria
can be
fi led for this evaluation assistance tool.
The evaluation is based on a complex A-scan com-
parison. The user
fi les a typical A-scan for each evalu-
ation criterion in the database. It is possible to fi le a
maximum of 20 typical A-scans per criterion which
can have 20 (max.) two-dimensional gates each, re-
cording as exactly as possible the characteristic curve
of the backwall or
fl aw echo sequence for the evalua-
tion.
During the inspection process, SpotChecker com-
pares the currently active A-scan with all A-scan char-
acteristics stored in the database and carries out the
evaluation after this, i.e. if the characteristics match,
the corresponding inspection criterion is displayed.
The software SpotChecker
Individual inspection reports
SpotChecker Issue 02, 03/2009
61