T.O. 33B-1-1Glossary 29EMULSIFIER-REMOVER (PT): A type of solvent that can be rinsed off with water after it is applied or used as asolvent wipe remover.EMULSIFICATION TIME (PT): Time required for the emulsifying agent to combine with the penetrant. This iscritical as insufficient time will result in failure to remove the penetrant and lead to false indications, and too long atime may remove the penetrant from the flaws. Emulsification time usually ranges from 30 seconds to 5 minutes.EMULSION (RT): The gelatinous substance in which fine grains of silver halides are dispersed. The emulsion iscoated on a base, usually polyester, and contains the image forming substance of a radiographic film.EMULSION FOG (RT): The slight density in an unexposed area of the film due to a small number of silver bromidecrystals developing spontaneously. Film speed and improper processing or storage will affect emulsion fog. Safelight,white light, or radiation fog is not considered part of emulsion fog.ENCAPSULATION: The process of sealing radioactive materials to prevent contamination.ENCIRCLING COIL (MT, ET): Coil(s) or coil assembly which surrounds) the part to be tested. Coils of this type arealso referred to as annular, circumferential, or feed-through coils.END EFFECT (ET, MT): The effect on the magnetic field caused by the geometric boundaries of the test specimen thatmakes it impractical to apply electromagnetic test methods to the associated regions of the test specimen; also calledEDGE EFFECT.ENDURANCE LIMIT: A value used to measure the load-carrying ability of a metal subjected to infinitely repeatedloading. It is determined from the S-N curve as the stress at which the curve becomes parallel to the N axis, i.e.; itprojects to an infinite number of cycles of stress without failure.ENDURANCE RATIO: Same as FATIGUE RATIO.ENERGY, RADIOGRAPHIC (RT): The energy of X-radiation is generally expressed in multiples of the electron volt(1,000,000 eV = 1,000 KeV = 1 MeV).EQUIAXED GRAIN STRUCTURE: A structure in which the grains have approximately the same dimensions in alldirections.EQUI-OPAQUE SUBSTANCE (RT): A material having radiation absorption similar to that of the specimen, appliedalong its edges or in its cavities in order to obtain homogeneous absorption and thereby avoid local overexposure of thefilm.EQUIVALENT PENETRAMETER SENSITIVITY (RT): The thickness of penetrameter, expressed as a percentage ofthe part thickness, in which the 2T hole would be visible under the same radiographic conditions.EROSION: Destruction of metals or other materials by the abrasive action of moving fluids usually accelerated by thepresence of solid particles or matter in suspension. When corrosion occurs simultaneously, the term erosion-corrosionis often used.ET: Symbol for eddy current method of nondestructive testing/inspection.ETCH CRACKS: Shallow cracks in hardened steel, containing high residual surface stresses, produced on etching inan embrittling acid.ETCHING: Subjecting the surface of a metal to preferential chemical or electrolytic attack in order to reveal structuraldetails.
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