Tracing electric

Apphcations requiring accurate temperature control are generally limited to electric tracing. For example chocolate lines cannot be exposed to steam temperatures or the product will degrade and if caustic soda is heated ove 150°F it becomes extremely corrosive to carbon steel pipes. 

For some applications, either steam or electricity is simply not available and this makes the decision. It is rarely economic to install a steam boiler just for tracing. Steam tracing is generally considered only when a boiler already exists or is going to be installed for some other primary purpose. Additional electric capacity can be provided in most situations for reasonable costs. It is considerably more expensive to supply steam from a long distance than it is to provide electricity. Unless steam is available close to the pipes being traced, the automatic choice is usually electric tracing. 

For most apphcations, particularly in processing plants, either steam tracing or electric tracing could be used, and the correct choice is dependent on the installed costs and the operating costs of the competing systems. 

Economics of Steam Tracing versus Electric Tracing The... 

The two key variables in the decision to use steam tracing or electric tracing are the temperature at which the pipe must be maintained and the distance to the supply of steam and a source of electricpower. 

Safety. While steam burns are fairly common, there are generally fewer safety concerns than with electric tracing. 

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. 

Lower in stalled and operating co.st.s. Most studies have shown that electric tracing is less expensive to install and less expensive to operate. This is true for most apphcations. However, for some applications, the installed costs of steam tracing are equal to or less than electric tracing. 

Temperature control. Even without a thermostat or any control system, an electric tracing system usually provides better temperature control than a steam tracing system. With thermostatic or electronic control, veiy accurate temperature control can be achieved. 

Poor reputation. In the past, electric tracing has been less than reliable. Due to past failures, some operating personnel are unwilling to take a chance on any electric tracing. 

Design requirements. A slightly higher level of design expertise is required for electric tracing than for steam tracing. 

Schisla, R. M., P. N. Lodal, and M. A. Paulonis (1996). "Use of the Semenov Model for the Analysis of Runaway Reactions Induced in Pipelines by Electrical Tracing." Proceedings of the 30th Annual Loss Prevention Symposium, February 26-28, 1996, New Orleans, LA, ed. R. P. Benedetti, J. J. Rooney, and K. Chatrathi, Paper 13d. New York American Institute of Chemical Engineers. 

Lower installed and operating costs. Most studies have shown that electric tracing is less expensive to install and less expensive to... 

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