in the secondary standard shall be used. Instrument sensitivity shall
be adjusted to 50 percent full-scale of the maximized response from the
reference hole at 1/2 maximum inspection distance. A reject/repair
line shall be constructed at 80 percent of the established
distance-amplitude curve. The reflection amplitudes to define this
curve shall be taken from the faces of the secondary sensitivity
standards which are 25 mm 1 inch, 50 mm 2 inch, and 1/2 maximum
inspection distance, and the longest distance obtainable from the
secondary standard, respectively, from the reference hole. When a
correction curve cannot be drawn on the face of the CRT, one of the
distance-amplitude correction methods noted above and submitted under
the procedure description shall be applied in accordance with paragraph
GENERAL REQUIREMENTS.
1.11.6
Longitudinal Wave Inspections Using Immersion Technique
The reference hole in a secondary standard shall be used for each different
inspection distance. Repair/reject limits shall be established by
immersing both the search unit and secondary standard in the liquid bath in
which the inspection is to be conducted. The procedure noted below shall
be used:
a. The longitudinal waves from the search unit shall be directed
toward the face of the secondary standard closest to the reference hole.
b. The search unit shall be positioned for maximum response. The
amplitude of reflection shall be adjusted to 50 percent full-scale.
The top of that indication shall be marked on the CRT with a wax pencil
or by other means. This establishes the standard reference level. A
point at 80 percent of the standard reference level shall be calculated
and marked. This locates the reject/repair point. The above shall be
repeated for each different surface-to-hole distance to establish the
reject/repair line.
c. With the gain at the same setting and the primary standard and
search unit in air, a maximized reflection shall be obtained from the
1.524 mm 0.06 inch reference hole in the primary standard (IIW). Then,
this gain setting shall be readjusted to obtain a 50 percent full-scale
reflection. The readjusted setting shall be recorded as required by
paragraph SUBMITTALS, SD-18 Records, to provide a basis for
recalibration when the secondary standard is unavailable.
PART 2
PRODUCTS (Not Applicable)
PART 3
EXECUTION
3.1
PREPARATION OF MATERIALS FOR INSPECTION
Surfaces shall be free from the following:
3.1.1
Weld Spatter
Spattering or any roughness that interferes with free movement of the
search unit or impairs transmission of the ultrasonic vibrations.
3.1.2
Irregularities
Those which could mask or be confused with defect indications.
SECTION 05091A
Page 19
Previous Page
