In the last decade AUT Phased Array (PA) based has become the most widely used NDT method to inspect girth welds during offshore pipeline construction in the Oil & Gas industry. The approach used is called "zonal discrimination". The extremely high achievable sensitivity of this technique for detecting and sizing real flaws is nowadays fully recognised worldwide particularly for carbon steel materials. This approach can both guarantee the quality of the welds produced and it can lead to possible relaxations of ECA based acceptance criteria. The collateral effect is that for some specific applications, Operators specifications set the target to really challenging limits (e.g. accuracy requested of 0.3mm for root and cap areas). This can be considered borderline between what is and what is not physically possible, particularly taking into account actual field conditions. Comparing AUT with Macro-sectioning, the aim of the paper is to analyse the good results achievable, as well as some possible issues for particular geometric conditions. Several case-studies are discussed and addressed such as the low amplitude response from a certain type of flaw on thin wall pipes, the risk of oversizing specific imperfections visible in more "zones" or the accurate assessment of the OD area.
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