T.O. 33B-1-1Glossary 77ROD-ANODE TUBE (RT): A special type of X-ray tube in which the target is situated at the outer end of a longtubular anode. It usually produces panoramic radiation.ROENTGEN ® (RT): The international unit of the quantity of X or gamma radiation which cause the emission of ionscarrying 1 electrostatic unit quantity of charge per 0.001293 grams of air. It is usually employed to express theradiation output of a given source in terms of roentgens per hour at one meter (Rhm). Under the International Systemof Units this will be expressed in coulombs/kilogram (1 r = 2.579560 x 10-4 C/ kg).ROENTGENS PER HOUR AT ONE METER (RT): A specification of the output of a source of X- or gamma radiationin terms of the exposure rate, in roentgens per hour, measured in air at a distance of one meter from the source.Abbreviation: Rhm.ROLL BENDING: Curving sheets, bars and sections by means of rolls.ROLL FLATTENING: Flattening of sheets, that have been rolled in packs, by passing them separately through a two-high cold mill, there being virtually no deformation. Not to be confused with roller leveling.ROLL FORGING: Forging with rotating dies that are not full round, the desired shape, either straight or tapered, beingproduced by a groove in the dies.ROLL FORMING: Metal forming by the use of power-driven rolls whose contour determines the shape of the product.Sometimes used to denote power spinning.ROLL STRAIGHTENING: Straightening of metal stock of various shapes by passing it through a series of staggeredrolls, the rolls usually being in horizontal and vertical planes.ROLLING: Reducing the cross-sectional area of metal stock, or otherwise shaping metal products, through the use ofrotating rolls.ROOT CRACK: A crack in either the weld or heat-affected zone at the root of a weld.ROOT OF JOINT: The location of closest approach between parts of a joint to be welded.ROOT PENETRATION: The depth to which weld metal extends into the root of a joint.ROTATING-ANODE TUBE (RT): An X-ray tube in which the anode can rotate. The axis of rotation is offset from theaxis of the electron beam, so that the focus lies on a circle on the rotating surface.ROUGHNESS: Relatively finely spaced surface irregularities, the height, width and direction of which establish thepredominant surface pattern.ROUGHNESS HEIGHT RATING: Quantitative expression of the roughness of a surface; arithmetical average,normally expressed in microinches, of the absolute values of surface height deviation from the mean surface height.Abbreviation is rhr.RT: Symbol for the radiographic method of nondestructive testing/inspection.RUPTURED METAL: See BURSTS.RUST: A corrosion product consisting of hydrated oxides of iron. Applied only to ferrous alloys.S
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