Having determined the weld diameters from the milled strip
using the C-scan images, the strip was destructively peeled to
determine the physical weld plug diameters. The as peeled strip is
shown in Fig. 10, where differences in weld plugs as weld currentchanged are revealed physically. Each plug was then measured
manually using a digital Vernier and an average of maximum and
minimum diameter was obtained.
The correlation between weld diameters determined using the
NDT technique and the actual measured peeled plug diameters is
shown in Fig. 11. The graph suggests that the NDT technique has a
practical usable accuracy with respect to weld plug diameters.
However, it is important to recognise that peeled plug size is not
necessarily a true measure of the fused area and can vary by up to
20%; as reported by previous authors [12]. This should be taken
into account within the procedure adopted for any specific NDT
applications and managed through measurement standards to
suit the manufacturer’s own criteria.