tests specified in paragraph EQUIPMENT QUALIFICATION REQUIREMENTS, and
shall be used as follows except where the IIW block is specifically
required:
a.
To assure adequate penetration of the base material.
b.
To provide a secondary field standard.
c. To calibrate the equipment and to establish the standard reference
level.
2.7.3
Resolution Test Block
The Contractor shall furnish a resolution test block in accordance with the
details shown in AWS D1.1/D1.1M, Section: Inspection, subsection Reference
Standards.
2.8
EQUIPMENT QUALIFICATION REQUIREMENTS
The ultrasonic instrument and accessories shall be evaluated on their
arrival at the jobsite just before the start of the inspection. They shall
be evaluated using the Contractor's furnished primary standard and shall
meet or exceed the requirements below. Equipment that does not meet these
requirements shall not be used.
2.8.1
Requalification
The equipment shall be requalified after normal use at intervals not to
exceed 40 hours. In addition, equipment shall be requalified immediately
after maintenance or repair or when the Contracting Officer considers its
operation questionable.
2.8.2
Longitudinal Wave System
2.8.2.1
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.
2.8.2.2
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 and 80 percent of full screen height.
For each gain setting, the amplitude of each reflection shall vary by the
same factor within plus or minus 5 percent.
2.8.2.3
Near-Surface Resolution
Excessive ringing that appears on the cathode ray tube (CRT) just 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 block and positioned for maximum amplitude reflection from the 1.52
mm 0.060 inch hole. The reference reflector shall be set to mid-screen and
the gain shall be increased 20 dB. In either case, excessive ringing shall
not appear on the CRT to the right of the sound entry point in excess of a
13 mm 1/2 inch equivalent distance in steel. The reference hole located at
SECTION 05092A
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