accessible, or when existing backing rings or backing strips are not
removed. For inspection of weldments containing backing rings or backing
strips, the instrument shall be adjusted and the refracted angles shall be
selected in a way to separate the weldment and the backing ring
reflections. The search unit angle and the resulting shear wave angle in
the material to be inspected shall be established by the Contractor for
each application and this information shall be included in the procedure
submitted for approval.
1.5.2
Longitudinal Waves
When conditions prohibit the use of shear waves, longitudinal waves may be
used. The procedure shall be specially developed to suit the application
and shall have the prior approval of the Contracting Officer.
1.6
CHANGES IN PROCEDURE
Should application of an approved procedure not provide for good resolution
or adequate ultrasonic penetration in the items to be inspected (see
paragraph EQUIPMENT QUALIFICATION REQUIREMENTS), changes in procedure or
equipment such as frequency, pulse repetition rate, angle of search unit,
couplant, or oscilloscope shall be made by the Contractor. Adequacy of the
new procedure shall be demonstrated to the Contracting Officer. The
Government reserves the right to require a change in test equipment during
these tests if any of the following test system characteristics fall below
the levels listed in paragraph EQUIPMENT QUALIFICATION REQUIREMENTS:
sensitivity, amplitude and distance linearity, signal-to-noise ratio, entry
and back surface resolution and penetration.
1.7
ULTRASONIC EQUIPMENT
The ultrasonic equipment shall conform to the requirements listed in AWS
D1.1/D1.1M Section Inspection, subsection Ultrasonic Equipment, with the
following exceptions:
a. The ultrasonic test instruments shall be able to generate, receive,
and to present pulses in the frequency range from 1 to 10 megahertz
(MHz).
b. The horizontal linearity of the ultrasonic instrument shall be
measured in accordance with paragraph EQUIPMENT QUALIFICATION
REQUIREMENTS.
c. In addition to the resolution test specified in AWS D1.1/D1.1M,
subsection Ultrasonic Equipment, both near- and far-surface resolution
tests shall be conducted in accordance with the tests specified for
these characteristics in the paragraph EQUIPMENT QUALIFICATION
REQUIREMENTS.
1.8
PERSONNEL QUALIFICATION AND REQUIREMENTS
1.8.1
Personnel Qualification
The three levels of responsibility associated with ultrasonic inspection
are defined in ASNT RP SNT-TC-1A. For qualification to perform ultrasonic
inspection, personnel shall be certified under ASNT RP SNT-TC-1A and ASNT
Q&A Bk C within a period of 1 year before the date of contract. Other
qualification or certification may be accepted at the Contracting Officer's
discretion. Personnel with only an operator or inspector trainee
SECTION 05091A
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