Ultrasonic testing – Techniques, testing levels and assessment

There is a standard that is coming closer to being issued covering the ultrasonic testing of welds: ISO/FDIS 17640:2017(E) Non-destructive testing of welds – Ultrasonic testing – Techniques, testing levels and assessment.

How many organisations are using the symbols given in the standard when reporting? How many reports contain the data required for h extension of the indication in depth direction and z position of the discontinuity in the depth direction?

I had the opportunity to visit an Authorised Qualifying Body (AQB) recently and some of the reports submitted by the candidates (not trained by their Accredited Training Organisation (ATO)) failed to provide this information. This reduces the marks that can be allocated to the candidate, as the CP22 marking scheme states:

3.2 Characterisation
Within the limitations of the NDT method, recording the nature of discontinuity
detected (surface and subsurface where applicable), its position and dimensions.
The candidate is expected to correctly state the nature of the reported indication. Candidate instructions will clarify what is expected in this respect, for example whether a simple description (volumetric or planar, crack-like indication) or a fuller description (fatigue crack, lack of sidew
all fusion, cold shut, stress corrosion cracking) is required.
The candidate will be expected to accurately report the position of the reported indication with respect to a given datum by giving two dimensions, longitudinal and transverse, for surface methods and three dimensions, length, through thickness and depth, for volumetric methods.
Defect dimensions must be correctly reported within the tolerance defined in the master report. The tolerance allowed will depend upon the NDT method/technique and the type/position of the defect.

There is then the additional concern relating to what the qualified UT operator will report when at
work and what the end-user is specifying that requires reporting. Now is the time to improve the information generated and reported on.

Indications will be considered to be originating from either longitudinal or transverse discontinuities, depending on the direction of their major dimensions with respect to the weld axis, x, in accordance with the following Figure.

For definitions of h, l, lx , ly , x, y and z, see the Table below.

  Symbol Definition Unit
 h Extension of the indication in depth direction
 lLength of the indication
 Projected length of the indication in the x direction
 ly Projected length of the indication in the y direction
 x Position of the discontinuity in the longitudinal direction
 y Position of the discontinuity in the transverse direction
 z Position of the discontinuity in the depth direction


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