frequency as defined in paragraph TEST FREQUENCY shall be used. Final
evaluation for acceptance or rejection shall be performed with the
equipment properly calibrated and the gain control set at the reference
level. The reject/repair line shall be used to evaluate the quality of
each item inspected. If a periodic calibration check shows that the
equipment is not operating properly or that the sensitivity of the system
has decreased more than 20 percent or 2 dB from the established sensitivity
level, all items that have been inspected since the previous calibration
shall be reexamined. When adequate penetration, as specified in paragraph
EQUIPMENT QUALIFICATION REQUIREMENTS, cannot be obtained by the proposed
longitudinal wave method, the Contractor shall modify the procedure in
accordance with paragraph CHANGES IN PROCEDURE.
3.2.1
Couplants
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NOTE: The designer may limit the choice of
couplants if some couplants are considered injurious
to the item to be inspected.
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The choice of couplant, such as oil or water, is optional with the
Contractor except as follows:
a. The couplant shall be the same as that used for equipment
qualification and calibration.
b. Couplants that may cause corrosion of the reference standards or
the material being tested shall not be used.
c. Oil shall not be used for plate to be installed in systems that
will handle liquid oxygen.
d. Couplants shall have the proper viscosity to overcome surface
roughness or irregularities.
3.2.2
Detection of Laminar Types of Flaws
a. The plates shall be marked off in grid lines with a maximum spacing
of 12 inches between lines, tested along each grid line and also along
a path within one thickness (T) of the plate from each plate edge.
b. The back or end reflection from the far surface of the plate shall
be maintained in excess of 40-percent of full-scale screen height
during the entire inspection to assure adequate ultrasonic penetration.
c. When a complete loss of back or end reflection occurs along any
grid line, the entire area of the square adjacent to that point shall
be inspected. Complete testing of all additional adjacent squares
shall be continued until the extent of the defective area is defined.
3.2.3
Detection of Lack of Bonding Between Base Plate and Cladding
a. The clad area shall be inspected for any lack of bonding between
the cladding and the base metal. The clad 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
SECTION 05092A
Page 19
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