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T > TUBE-TO-HEADER "SEAL" WELDS - Pg. 253

TYPE DESIGNATION TRANSONIC Pertaining to the speed of a vehicle moving through a surrounding fluid, when certain portions of the vehicle are travel- ing at subsonic speeds while other portions are moving at super- sonic speeds. TRANSPASSIVE A noble region of potential where an electrode exhibits a higher than passive current density. TRANSPONDER Usually, a beacon containing a receiver and a transmitter. The purpose is to increase the energy level of the target or missile signal so that the surveillance range can be extended. TRIM LINES Lines that define the borders of a printed board. See also Corner mark. TRUE POSITION The theoretically exact location of a feature established by basic dimensions. Obsolete term; see Positional tol- erance. TUBE BEND DRAWING A tube bend drawing establishes, by pictorial or tabular delineation or a combination thereof, end prod- uct definition for a single, multiplane, tube, or tube assembly (tube with end fittings). It establishes item identification for the bend tube or tube assembly. TUBE-TO-HEADER "SEAL" WELDS Welds between various types of boiler tubes and their respective headers (or drums), such as economizer headers, superheater headers, and so forth. These welds are located on the interior of the header (or drum). Integrity of the tube-to-header connection is provided by a combination of welding and rolling the tube. TWIST The deformation parallel to a diagonal of a rectangular sheet such that one of the corners is not in the plane containing the other three corners. TYPE This term implies differences in like items or processes rela- tive to design, model, shape, etc. and is usually designated by Roman numerals, thus "Type I, "Type II," etc. TYPE DESIGNATION A combination of letter and numerals arranged in a specific sequence to provide a short significant method of identification. 253