Operating Manual

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15.2 The film-interpreter
Apart from the requirements regarding “viewing conditions” and “viewing equipment”
the film-interpreter (film viewer) shall have thorough knowledge of the manufacturing
process of the object being examined and of any defects it may contain. The type of
defects that may occur in castings, obviously, differs from those in welded constructions.
Different welding processes have their own characteristic defects which the film inter-
preter must know to be able to interpret the radiograph.
To become a qualified NDT operator, various training courses, course materials and leaf-
lets specifying the requirements they need to comply with, exist. The European NDT-
industry conforms to the qualification standards of the American ASNT organisation.
So far, a training programme for film-interpreter has not been established in similar
fashion. Textbooks for example are not uniform. Sometimes, the IIW-weld defect refe-
rence collection is used, beside which the instructor usually has his own collection of
typical examples, supplemented with process-specific radiographs.
ASTM has a reference set of defects in castings available.
There are incidental initiatives to introduce classification of film-interpreters by level, in
a system comparable to the qualification of NDT-personnel. Some countries have alrea-
dy implemented such a system.
15.3 Reference radiographs
The two main areas for the application of radiography are weld examination and
examination of castings. Radiography is also used to check complex assemblies for pro-
per construction, and for many other technical applications. The following selection of
radiographs illustrates the wide variety of possibilities for detection possibilities of
defects or errors.
Weld inspection:
The following examples are from the booklet published by GE Inspection Technologies,
called “Radiographer’s Weld Interpretation Reference”
Note: All of these examples illustrating a variety of defects in welds are also issued on poster
format (60 x 90 cm) by GE Inspectio technologies.
Offset or mismatch (Hi-Lo).
An abrupt change in film density across the width
of the weld image
Offset or mismatch with Lack of Penetration (LOP).
An abrupt density change across the width of the weld image
with a straight longitudinal darker density line at the centre of
the width of the weld image along the edge of the density change.