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1. GENERAL ORGANIZATION OF THE PROGRAM
The ultrasonic testing equipment characterization program is divided
into three principal phases:
1.1. Qualification of a type of equipment
Given that, in the current state of the market, it is practically impossible
to obtain from manufacturers a sufficiently detailed
specification of their product, as well as a guarantee with regard to
their planned performance, the only possible approach consists in
imposing on the equipments purchased an internal specification
and to classify them into different categories according to the
results of these measurements.
From this fact, the preliminary phase is subdivided in the following
way (fig.1) :
a) Qualification of a type of item
When a type of probe or instrument is envisaged with a particular
application in view, its capacity to carry out the required
performances is checked in laboratory.
b) Item analysis
If the performance seems satisfactory, the characteristics of the
equipment under examination are noted. This stage is applied
not only to the instrument, to the cable or to the transducer,
but equally to the unit that they constitute.
c) Definition of qualification criteria
These detailed measurements are repeated on a number of items
sufficient to determine the nominal value and the acceptable
tolerance of each characteristic.
These three stages are applied on each group of instruments,
cables and transducers, each time that it is considered necessary
to add a new element to the equipment store, or to replace one
of these elements.
If a characteristic presents a considerable dispersion, one can
define several families, in attributing to each one of them
specific tolerance limits, in such a way as to be able to assure
the reproducibility of inspection results without having to reject
an excessive number of items.
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