The Contractor shall furnish a resolution test block in accordance with the
details shown in AWS D1.1/D1.1M Section Inspection, subsection Ultrasonic
Equipment.
1.10
EQUIPMENT QUALIFICATION REQUIREMENTS
The ultrasonic instrument and accessories shall be evaluated on their
arrival at the jobsite, immediately prior to the start of inspection. They
shall be evaluated using the Contractor's furnished primary standard and
shall meet or exceed the requirements listed in paragraphs below.
Equipment that does not meet these requirements shall not be used in the
inspection.
1.10.1
Requalifications
The equipment shall be requalified after normal use at intervals not to
exceed 40 hours, except as noted. The equipment also shall be requalified
immediately after maintenance or repair or when the Contracting Officer
considers its operation questionable.
1.10.2
Longitudinal Wave System
1.10.2.1
Vertical Amplitude Linearity
Two adjacent reflections of different amplitudes obtained through the
thickness of the primary or secondary standard shall vary in the same
proportion as the amplitude of the first reflection is increased in
discrete 2-dB increments between 20 percent and 80 percent to full screen
height. For each gain setting, the amplitude of each reflection shall vary
by the same factor, within plus or minus 5 percent. Requalification is
required monthly or as otherwise stated.
1.10.2.2
Horizontal Linearity
The first three multiple reflections obtained through the thickness of the
primary or secondary standard shall be equally spaced, within plus or minus
5 percent, when spread over 90 percent of the sweep length.
Requalification is required monthly or as otherwise stated.
1.10.2.3
Near-Surface Resolution
Excessive ringing that appears on the CRT to the right of the sound entry
point shall not exceed a 13 mm 1/2 inch equivalent distance in steel with
the search unit placed on the 100 mm 4 inch edge of the IIW (primary) block
and positioned for maximum amplitude reflection from the 1.524 mm 0.06 inch
reference hole of the primary standard. The reference reflector shall be
set to mid-screen and the gain shall be increased 20 dB. The reference
hole located at least 13 mm 1/2 inch from one edge of the AW DSC or SC
secondary standard shall be used similarly. Acceptability will be on the
same basis as in the primary standard.
1.10.2.4
Far-Surface Resolution
This property of the equipment shall be verified by the method detailed in
AWS D1.1/D1.1M, Section Inspection, subsection Calibration of the
Ultrasonic Unit with the IIW or Other Approved Calibration Blocks. In
addition, the trailing edge of the third reflection shall return to the
sweep line and be clearly discernible.
SECTION 05091A
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