Chapter 18 Weld Inspection and Repair
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• Optical Comparator. Magnifi es, illuminates,
and precisely measures weld discontinuities.
• Magnifi cation lenses. Pocket-sized
magnifi cation lenses.
• Extension mirrors. Used for root pass
inspection of pipe welds
• Fillet weld gauge. Measures the size of fi llet
welds.
• V-WAC gauge. Used for measuring height
and depth. The gauge checks undercut
depth, porosity comparison, amount of
porosity per linear inch and crown height.
• Automatic weld size gauge. Measures several
aspects of a weld, including the height.
• Bridge cam gauge. Used for measuring
several aspects of welds, such as depth of
undercut, depth of pitting, and fi llet weld
throat size and leg length.
Visual tests provide very important informa-
tion about a weld’s general conformity to specifi ca-
tions. The following weld features are measured and
compared to specifi cations to ensure that the weld
meets expectations:
• crown height
• crown profi le
• weld size
• weld length
• dimensional variation
• root side profi le
• root side penetration
• surface color (titanium welds)
In addition, a visual test may reveal discontinui-
ties in the weld. A discontinuity is any disruption
in the consistency of a weld. A fl aw in the weld is
a discontinuity that is small enough that it does not
render the weld unacceptable. A defect is a disconti-
nuity that is serious enough to make the weld unac-
ceptable. The following common problems can be
detected by visual tests:
• underfi ll
• undercut
• overlap
• surface cracks
• crater cracks
• surface porosity
• joint mismatch
• warpage
Penetrant Test
A penetrant test (PT) is a sensitive method of
detecting and locating minute discontinuities that are
open to the surface of the weld. A penetrating liquid
(dye) is applied over the surface of the weld. The fl uid
then enters the discontinuity. After a short period of
time, the excess penetrant is removed from the surface.
A developer is applied to the surface and allowed to
dry. The penetrant in the discontinuity rises to the
surface by capillary action, making the discontinuity
easy to see. The penetrant test sequence is shown in
Figure 18-4.
Figure 18-2. Fillet weld size and crown gauge. (Mark Prosser)
Figure 18-3. This adjustable fi llet and crown gauge is being
used to check the height of the weld bead. (Mark Prosser)