T.O. 33B-1-1
Glossary 26
DRYING OVEN (PT): An oven used for drying rinse water from test pieces.
DRYING TIME (PT): The time during which a washed or wet-developed part is in the hot air drying oven.
DRY METHOD (MT): Magnetic particle inspection in which the particles are applied in a dry powder form.
DRY POWDER (MT): Finely divided ferromagnetic particles suitably selected and prepared for magnetic particle
inspection. Colors employed are usually red, gray, yellow or black.
DUAL SEARCH UNIT (UT): A single search unit containing two transducer elements; one used as a transmitter of
ultrasonic energy, the other used as a receiver of ultrasonic energy.
DUCTILE CRACK PROPAGATION: Slow crack propagation that is accompanied by noticeable plastic deformation
and requires energy to be supplied from outside the body.
DUCTILITY: The ability of a material to deform plastically without fracturing, being measured by elongation or
reduction of area in a tensile test, by height of cupping in an Erichsen test or by other means.
DUPLITIZED FILM (RT): Radiographic film that consists of a coating of photosensitivity emulsion on both sides of
the tinted polyester base.
DWELL TIME (PT): The period of time wherein the liquid penetrant remains on the surface of the part. For the
immersion techniques, the period subsequent to soak and prior to wash, i.e., draining process is considered dwell time.
DYE: The chemical component added to a penetrant vehicle to provide a characteristic color to the penetrant.
DYE PENETRANT: Penetrant with dye added that makes it readily visible in light.
DYE STUFFS (MT, PT): A natural or synthetic coloring matter whether soluble or insoluble that is used to color
materials usually from a solution or fine dispersion and sometimes with the aid of a chemical (mordant) that serves to
fix a dye in or on a substance.
DYNAMIC CREEP: Creep that occurs under conditions of fluctuating load or fluctuating temperature.
DYNAMIC RANGE (UT): The ratio of maximum to minimum reflective areas that can be distinguished on the
cathode ray tube at a constant gain setting.
E
ECHO: Signal of reflected ultrasonic energy.
EDDY CURRENTS: Currents caused to flow in an electrical conductor by the time and/or space variation of an applied
magnetic field.
EDDY CURRENT INSPECTION OR TESTING: A nondestructive inspection method in which eddy current flow is
induced in the test object. Changes in the flow caused by the variations in the specimen are reflected into a nearby coil
or coils for subsequent analysis by suitable instrumentation and techniques.
EDDY-SONIC (UT, ET): Describes a process in which sonic or ultra-sonic energy is produced in a test part by coil on
or near the surface of the test part. The coil is used to produce eddy currents in the test part. Vibrations in the test part
result from the interaction of the magnetic field from the eddy currents in the test part with the magnetic field of the
coil.
