Tracing/tracers

TP-T tr or T target practice, tracer trace, tracer TTE Tropical Testing Establishment (Brit)... 

Trace metal Trace metal contents Trace metals Tracer applications Tracer bullets Tracers... 

The detection and determination of traces of cobalt is of concern in such diverse areas as soflds, plants, fertilizers (qv), stainless and other steels for nuclear energy equipment (see Steel), high purity fissile materials (U, Th), refractory metals (Ta, Nb, Mo, and W), and semiconductors (qv). Useful techniques are spectrophotometry, polarography, emission spectrography, flame photometry, x-ray fluorescence, activation analysis, tracers, and mass spectrography, chromatography, and ion exchange (19) (see Analytical TffiTHODS Spectroscopy, optical Trace and residue analysis). 

Half-inch copper tubing is commonly used for steam tracing. Three-eighths-inch tubing is also used, but the effective circuit length is then decreased from 150 feet to about 60 feet. In some corrosive environments, stainless steel tubing is used, and occasionally standard carbon steel pipe (one half inch to one inch) is used as the tracer. 

High in stalled co.sts. The incremental piping required for the steam supply system and the condensate return system must be installed, insulated, and, in the case of the supply system, additional steam traps are often required. The tracer itself is not expensive, but the labor required for installation is relatively high. Studies have shown that steam tracing svstems typically cost from 50 to 150 percent more than a comparable electric tracing system. 

Electric Tracing An electric tracing system (see Fig. 10-178) consists of an electric heater placed against the pipe under the thermal insulation, the supply of electricity to the tracer, and any control or monitoring system that may be used (optional). The supply of electricity to the tracer usually consists of an electrical panel and electrical conduit or cable trays. Depending on the size or the tracing system and the capacity of the existing electrical system, an additional transformer may be required. 

The abundance of a trace element is often too small to be accurately quantihed using conventional analytical methods such as ion chromatography or mass spectrometry. It is possible, however, to precisely determine very low concentrations of a constituent by measuring its radioactive decay properties. In order to understand how U-Th series radionuclides can provide such low-level tracer information, a brief review of the basic principles of radioactive decay and the application of these radionuclides as geochronological tools is useful. " The U-Th decay series together consist of 36 radionuclides that are isotopes (same atomic number, Z, different atomic mass, M) of 10 distinct elements (Figure 1). Some of these are very short-lived (tj j 1 -nd are thus not directly useful as marine tracers. It is the other radioisotopes with half-lives greater than 1 day that are most useful and are the focus of this chapter. 

To maintain a desired temperature in the process pipe, it may be necessary to use 1, 2, or 3 tracer tubes (small pipes) located symmetrically around the pipe and running parallel to the pipe however, at valves and fittings, the tracing needs to be so placed as to provide protection uniformly to the surface. Some designers recommend arranging the tracing in the lower half of the pipe. 

Fleat transfer cements are quite useful for transferring the heat from an external tracing when attached outside of the process pipe, Figures 10-167 and 10-168. To determine the number of heat transfer steam tracers, it is important to contact the manufacturer of the heat transfer cement. The illustrations here should be considered preliminary for approximating purposes. The information/data that follows is used with permission from Thermon Manufacturing Co./Cellex Div. Except for specific conditions, most applications represent the requirements to maintain a pipe (or vessel) system temperature, not to raise or lower the temperature. 

At the top end of the program monitoring scale is the use of online fluorescence tracing systems, whereby tracer dye polymers form part of the water treatment program and their concentration can be measured online at various locations throughout the boiler plant system. Much less expensive, handheld fluorometers are now available to conduct the same type of analysis at the laboratory bench or on the boiler house firing-floor. These tracer dye polymers can be used to determine ... 

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