OmniScan MX2 Training ProgramPhased Array Analysis

Flaw Volumetric Position

2OmniScan MX2 Training Analysis Flaw Volumetric Position Overview Flaw volumetric position is defined as the

position of the flaw relative to the weld or component.

For weld inspection it is is typically expressed as negative or positive in relation to the weld centerline or weld reference, and either embedded, connected to the ID, or connected to the OD.

The flaw volumetric position is a key indicator for determining what type of defect has been detected. (Slag, porosity, IP, LOF, ext.)

Knowledge of the weld bevel and weld process is extremely helpful. In a V weld, IP would occur in the bottom root area, obviously. In a X weld IP would occur in the weld center.

Regardless if volumetric position is a requirement of the referencing code, knowing the volumetric position is necessary to make the repair. Where to excavate and how deep and long?

Sk90 (-) Sk270 (+)

SWLF flaw on weld overlay

Weld Centerline

3OmniScan MX2 Training Analysis Flaw Volumetric Position - Overlay Weld overlays are the primary indicator for determining volumetric flaw position. Using the part and weld wizard almost any symmetrical or asymmetrical weld can

be created and displayed on the S-scan.

The weld overlays should be considered close approximations when used to determine flaw location. The overlay is dependent on the scanner or manual probe position being maintained or entered with a high level of precision for them to be useful.

Slag Inadequate penetration OD connected crack

4OmniScan MX2 Training Analysis Volumetric Position VIA Reading The VIA reading displays the distance between the weld centerline and the

maximum amplitude signal in gate A (VIA) or gate B (VIB). VIA is short for volumetric position on the index axis of the signal in gate A. It is

expressed either (-) or positive relative to the weld centerline. The VIA and DA readings are the primary indicators for excavating a flaw for the

repair. (Where to dig and how deep)

ID connected crack -3.88mm from weld CL Inadequate penetration at weld CL

-3.88mm

7.96mm

5OmniScan MX2 Training Analysis Volumetric Position Skip Lines In addition to the weld overlays, the MX2 displays skip lines representing the part

thickness and successive skips. B0 (first backwall), T1 (second skip), B1 (second backwall), etc.

The B0 and T1 skip lines are visual indicators that assist in skip orientation and differentiation between OD connected, embedded, and ID connected defects.

In the image below, the crack is detected well before T1 (Full skip) and well after T1 (Second skip) indicating that the crack is connected to the OD surface.

OD connected crack on full skip

14.10mm3.21mm

B0

T1

B2

57.5 degree focal law

LA 1LA 2Flaw

location

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