The table below indicates some of the more common indications and the weld process they are associated with. Defects detected with UT are compared to calibration reflectors and therefore through wall thickness dimensions and position. The percentages given are not intended to be exact values but merely estimates to show the POD due to the physical limitations of the various methods. To illustrate the ease with which these defects can be identified the following examples are provided. To explain the stripchart presentation we have provided the graphic display of how the gated output is represented as a point on the chart.
Several variations can occur.
The internal welding head did not fire or sputtered. No metal is deposited. Ideally this presents 2 smooth root faces, however, welders have been known to see this from the outside and the Hot Pass bug can be run over the area twice. This can cause some metal to penetrate and reduce the surface area of nonfused root face. Due to misalignment of the internal head or high low conditions, one side of the root bevel may not get metal deposited on it.