interface between the base plate and overlay can be resolved.
3.2.4
Detection of Lack of Fusion Between Welded Overlay and Base Plate
a. The fusion-welded area shall
be inspected for any lack of fusion
between the overlay and the base
plate. The fusion-welded area shall
be marked off in grid lines with
a maximum spacing of 150 mm 6 inches
between lines, tested along each
grid line and also along a path within
T of each edge.
b. The inspection shall be made from the base metal side, provided the
interface between the base plate and overlay can be resolved.
3.2.5
Immersion Techniques for Longitudinal Wave Inspection
This procedure may be used at the Contractor's option unless otherwise
specified. Plates shall be inspected for laminar type of flaws, lack of
bonding between base plate and cladding, or lack of fusion between welded
overlay and the base metal, as appropriate. In addition, provision shall
be made for immersing the plate and mounting the transducer in a fixture so
that its motion along the required grid patterns can be controlled
accurately.
3.3
ACCEPTANCE/REJECTION LIMITS
Discontinuities shall be evaluated only when the ultrasonic equipment is
properly calibrated. If discontinuities are detected, the sound beam shall
be directed to maximize the signal amplitude. To determine the length of a
discontinuity, the search unit shall be moved parallel to the discontinuity
axis in both directions from the position of maximum signal amplitude.
One-half the amplitude (or a 6-dB increase in sensitivity) from a point at
which the discontinuity signal drops rapidly to the baseline shall be
defined as the extremity of the discontinuity. For discontinuities whose
signal amplitudes exceed full screen height, 50-percent full-screen shall
be considered half peak amplitude of the signal. At this point, the
scanning surface shall be marked at the position indicated by the center of
the transducer. This procedure shall be repeated to determine the other
extremity. The length of the discontinuity shall be defined as the
distance between these two marks. The maximum signal amplitude, length,
depth, and position within the inspection zone shall be determined and
reported for discontinuities yielding a signal amplitude equal to or
exceeding the reject/repair line. The minimum recordable length of
discontinuity shall be 13 mm 1/2 inch.
3.3.1
Investigation of Questionable Indications
Any indications considered doubtful shall be brought to the attention of
the Contracting Officer, and the plate shall be repaired or investigated
further as directed. Indications detected within 10 mm 3/8 inch or less of
accessible surfaces shall be investigated further by liquid penetrant as
provided in ASTM E 165, or by magnetic particle methods in accordance with
ASTM E 709, as applicable, to determine if they penetrate the surface.
Failure to locate the flaws by one of these methods shall require further
investigation by the other. For nonmagnetic materials, only dye penetrant
inspection is required. Other questionable defects shall be further
investigated by modifications of the inspection procedure in accordance
with paragraph CHANGES IN PROCEDURE.
SECTION 05092A
Page 20
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