T.O. 33B-1-1Glossary 80SCREEN-TYPE FILM (RT): A radiographic film produced specially to be used with fluorescent screens. This type offilm has high sensitivity to the fluorescent light emitted by such screens under the effect of ionizing radiation.(Improperly called screen film.)SCREEN UNSHARPNESS (RT): See UNSHARPNESS.SEALED SOURCE: Any by-product material that is encased in a capsule designed to prevent leakage or escape of theby-product material.SEALING:(1) Closing pores in anodic coatings to render them less absorbent.(2) Plugging leaks in a casting by introducing thermosetting plastics into porous areas and subsequentlysetting the plastic with heat.SEAM: A discontinuity caused by a void or crack in rolled material parallel to the axis of the material which althoughclosed is not welded. A line of junction; a line, groove, ridge, or interstice formed by or between two contracting edges.SEARCH UNIT (UT): A device for generating and/or receiving ultrasonic energy; may contain one or more transducerelements or, in the case of the Harmonic Bond Tester, a microphone and coil.SEASON CRACKING: Cracking resulting from the combined effects of corrosion and internal stress. A term usuallyapplied to stress-corrosion cracking of brass.SECONDARY MAGNETIC FIELD (ET): In eddy current testing, the magnetic field produced by the eddy currents inthe test material. The secondary field opposes the primary field.SECONDARY RADIATION (RT): Radiation other than primary radiation emerging from irradiated matter.SEEABILITY (PT, MT): The characteristic of an indication that enables an observer to see it against the conditions ofbackground, outside light, etc.SEGREGATION: Where a metallic constituent which cools last, forms a final brittle film between crystals. It may alsobe a concentration of non-metallic impurities. Segregations may occur at the center or be grouped in some regular formabout the center.SELF-ABSORPTION: Gamma ray emission from large sources wherein the gamma radiation emitted from the centerof the source will be appreciably absorbed by the outer layers of the source material.SELF-EMULSIFIABLE (PT): (Water-Washable) Self-emulsifiable material is an oil base material containing anemulsifying agent that forms an emulsion when rinsed with water.SELF-RECTIFYING TUBE (RT): Any hot-cathode X-ray tube that permits current to flow only from the cathode to theanode, when the anode is kept cool.SEMI-KILLED STEEL: Steel that is incompletely deoxidized and contains sufficient dissolved oxygen to react with thecarbon to form carbon monoxide to offset solidification shrinkage.SEMIPERMANENT MOLD: A permanent mold in which sand or plastic cores are used.SENSITIVITY (MT, ET, RT, PT, UT): The capacity or degree of responsiveness to magnetic particle inspection. Theability of an ultrasonic system to detect a very small discontinuity. The ability of a penetrant to detect surface defects.Higher sensitivity indicates finer cracks can be detected.
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