An informational site dedicated to process control education. Posts on this blog contain interesting and noteworthy information about process instrumentation, valves, and equipment used in industrial and municipal facilities. This blog is sponsored by Instrument Specialties, Inc. (ISI). For more information, please visit ISI.GROUP
Heat tracing of process piping is important to the successful maintenance or operation of systems containing heat sensitive fluids or installed in cold environments. Properly installing heat trace cable is essential to establishing effective and safe operation.
Raychem, a Pentair brand, provides an instructive video showing how to correctly install heating cables on the exterior of piping systems. Some of the content may be specific to Raychem products, but the general concepts have application to many installations and will help build knowledge and expertise.
Share your piping system heat trace requirements and challenges with a product expert, combining your process and facilities knowledge with their product application expertise to develop effective solutions.
Self-regulating heat tracing systems are the preferred choice for most complex pipe-tracing applications. This is due to their parallel construction, which allows them to be cut to length and spliced in the field, and their self-regulating output, which provides more heat where it is needed.
Self-regulating cable uses conductive-polymer technology in both monolithic (solid core) and fiber (polymeric fiber wrap) heating cables. The heating element is made of polymers mixed with conductive carbon black. This special blend of materials creates electrical paths for conducting current between the parallel bus wires along the entire cable length.
In each heating cable the number of electrical paths between the bus wires changes in response to temperature fluctuations. As the ambient temperature surrounding the heating cable decreases, the conductive core or fiber contracts microscopically. This contraction decreases electrical resistance and creates numerous electrical paths between the bus wires. Current flows across these paths to warm the core or fiber.
The document below provides an excellent detailed description of self-regulating cable, its application and selection.
Self regulation heating cable in used in many industrial and commercial applications to maintain temperatures in pipes. vessels, and tanks. Whereas constant wattage cables produces the same power output irrespective of process temperature, self regulating cable automatically adjusts the power output depending on process temperature.
For example, during a startup or when ambient conditions are cold, the fluid in the pipe may require more heating power to maintain the desired process temperature. In this situation, the self regulating cable will produce a higher wattage per foot to heat the pipe. As the process media temperature increases, then need for that amount of input power decreases, and the self regulating cable automatically cuts the power output accordingly.
This video, courtesy of Raychem, provides a short but informative understanding of how self regulating heat tracing cable (sometimes referred to as "heat tape") works.
