1.2.33
Node
Distance a shear wave travels in a straight line from the inspection
surface before being reflected by the opposite surface.
1.2.34
Pulse Repetition Rate
Number of spaced pulses of sound per second sent into the material being
inspected.
1.2.35
Range Control
Means of expanding the pattern obtained on the CRT so any portion of the
total distance being tested can be presented.
1.2.36
Reference Reflector
Standard reflector 1.52 mm 0.060 inch diameter reference hole in the IIW
reference block. Other approved blocks may have a different diameter
reflector.
1.2.37
Reflector
Boundary, consisting of an opposite side, crack, or separation, or a
distinct change in material such as slag or porosity that reflects the
ultrasonic energy the same as a mirror reflects light.
1.2.38
Refracted Waves
Waves that have undergone change of velocity and direction by passing from
one material to another material with different acoustical properties.
Refraction will occur wherever the angle of the incident wave to the
interface is other than perpendicular.
1.2.39
Rejectable Discontinuity (Defect)
Reflector large enough to produce a signal (decibel rating) that exceeds
the reject/repair line.
1.2.40
Resolution
Ability to clearly distinguish signals obtained from two reflective
surfaces with a minimum separation distance. Near-surface resolution is
the ability to clearly distinguish a signal from a reflector at a minimum
distance under the contact or near surface without interference from the
initial pulse signal. Far-surface resolution is the ability to clearly
distinguish signals from reflectors displaced at minimum distance from the
far or back surface when the sound beam is normal to that back surface.
1.2.41
Ringing
Excitation of the transducer crystal due to a short pulse of high-voltage
1.2.42
Scanning
Process of moving the search unit or units along a test surface to obtain
complete inspection of the entire volume of a material being inspected.
SECTION 05092A
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