1.2.45
Shear Waves
Waves in which the particles within the material vibrate perpendicularly to
the direction in which the wave travels or propagates. Also called
1.2.46
Shear Wave Inspection
Inspection technique using shear waves in a material. The search unit is
placed at an angle to the contact surface of the material so the resultant
refracted sound is a shear wave at an angle to the normal.
1.2.47
Standard Reference Level
Mid-screen height reflection when beaming at the 1.52 mm 0.06 inch hole in
the primary reference block or the reference hole in the secondary standard.
1.2.48
Surface Waves
Waves that propagate along the surface of the material and penetrate it to
only about 1/2-wavelength. Also known as Rayleigh waves.
1.2.49
Test Frequency
Operating frequency in hertz per second of the search unit during period of
activation. Frequency is usually expressed in megacycles per second or
megahertz. The latter term has been adopted for international use and is
preferred.
1.2.50
Video Form
Type of signal presentation on a CRT in which only the upper half of the
signal appears.
1.3
GENERAL REQUIREMENTS
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NOTE: Welded joints to be inspected will be shown
on the drawings, stated in other sections, or added
to this paragraph. Because accessibility and
geometry of the joint are factors in obtaining
adequate ultrasonic penetration, the designer should
consider these factors in the design of the joint.
Drawings or listings in the specifications must
clearly indicate which weld joints are to be
inspected ultrasonically.
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The procedures, methods, standards, and description of equipment specified
herein shall be used for inspection of weldments. Ultrasonic inspections
shall be made to detect the following defects:
a.
Cracks or crack-like faults.
b.
Root defects, including lack of penetration and fusion.
c.
Lack of fusion between passes on the sidewall.
SECTION 05091A
Page 10
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