UT: Symbol for the ultrasonic method of nondestructive testing/inspection.
v: Symbol for velocity.
V-PATH: See SKIP DISTANCE.
VACUUM DEPOSITION: Condensation of thin metal coatings on the cool surface of work in a vacuum.
VACUUM MELTING: Melting in a vacuum to prevent contamination from air, as well as to remove gases already
dissolved in the metal; the solidification may also be carried out in a vacuum or at low pressure.
VAN DE GRAAF GENERATOR: An electrostatic type X-ray generator in the million and multi-million volt category.
VECTOR FIELD (MT): See FIELD, RESULTANT.
VELOCITY (UT): The distance an ultrasonic wave travels in unit time.
VERTICAL LIMIT (UT): The maximum readable level of vertical indications, determined either by an electrical or a
physical limit of an A-scan presentation.
VERTICAL LINEARITY (UT): Constant relationship between the amplitude of the indications on an A-scan display
and the corresponding magnitudes of the reflected ultrasonic waves from reflectors of known size.
VERY HIGH RADIATION AREA: An area, accessible to individuals, in which radiation levels could result in an
individual receiving an absorbed dose in excess of 500 rads (5 grays) in 1 hour 1 meter from a radiation source or from
any surface that the radiation penetrates.
At very high doses received at high dose rates, unit of absorbed dose (e.g., rads and grays) are appropriate, rather than
units of dose equivalent (e.g., rems and sieverts).
The maximum dose rate 1 meter from the aperture of the Lorad LPX-160A Industrial X-ray Unit is 2.4 grays (240
RDAs) per minute at 0.5 meters thus the maximum dose received in one hour would equate to about 0.6 grays (60
RDAs) per minute. As such, "Very High Radiation" areas can exist for this and comparable radiation sources.
VIBRATION MODE (UT): See MODE OF VIBRATION.
VICKERS HARDNESS TEST: Same as diamond pyramid hardness test.
VIDEO PRESENTATION (UT): A CRT presentation in which rectified signals are displayed.
VIEWING MASK (RT): A device for limiting the field of examination of the radiograph.
VISCOSITY: Quality, state or degree of being viscous. That property of a body by virtue of which, when flow occurs
inside it, forces arise in such a direction as to opposite the flow.
VISCOSITY: A measurement of a liquids resistance to change of shape or flow. Also referred to as flow resistance.
VISIBLE: Capable of being discerned by the eye.