This design guide addresses the heat tracing requirements of complex piping. Whether the application is a small project or a complete network of piping and equipment, designing an electric heat tracing system for complex piping is simplified by using Thermon self-regulating cables. The information contained in this design guide will take the reader through a step-by-step procedure to make proper heating cable selections based on:
|• Pipe size||• Minimum ambient temperature|
|• Thermal insulation type and thickness||• Heating cable start-up temperature|
|• Desired maintenance temperature||• Available power supply|
|• Maximum exposure temperature||• Electrical area classification|
After following the prescribed steps in this design guide, the reader will be able to design, select and/or specify or establish a bill of materials for a heat tracing system.
Typically, complex piping is located inside a process unit and consists of relatively short runs of pipe with frequent tees, as well as in-line valves, pumps and related process equipment that also requires heat tracing. Circuit lengths can range from several feet (less than one meter) to several hundred feet (meters) in length; however, the average is usually 100 feet (30 meters) or less.
For applications ranging from freeze protecting water lines to maintaining elevated process temperatures as high as 300°F (149°C), Thermon self-regulating, cut-to-length, parallel resistance heating cables are recommended. Variations in the heat loss of the insulated pipe (due to equipment, supports and/or insulation) are compensated for by the heating cable’s PTC (Positive Temperature Coefficient) characteristic. Thermon offers heating cables specifically designed, manufactured and approved to cover a wide range of applications.
BSX ™ . . . Designed for freeze protection and temperature maintenance at or below 150°F (65°C), BSX is well-suited for both metallic and nonmetallic piping and equipment.
RSX ™ 15-2 . . . Designed for applications where the watt density requirements preclude the use of the standard range of BSX cables.
HTSX ™ . . . Designed for process temperature maintenance or freeze protection applications up to 250°F (121°C) and withstand intermittent exposure temperatures (power-on) up to 420°F (215°C), intermittent exposure temperatures (power-off) up to 482°F (250°C) and continuous exposure (power-off) to 400°F (204°C). The cable is capable of withstanding the exposure temperatures associated with steam purging.
VSX ™ . . . Designed for process temperature maintenance or freeze protection applications up to 300°F (149°C) and withstand intermittent exposure temperatures (power-on) up to 450°F (232°C), intermittent exposure temperatures (power-off) up to 482°F (250°C) and continuous exposure (power-off) to 400°F (204°C).
. . . Thermon has developed a sophisticated yet easy-to-use computer program, CompuTrace®, that provides detailed design and performance information. Users of CompuTrace are able to input application-specific information into the program and obtain detailed electrical and thermal performance information. Calculations made within the program are based on the formulas prescribed in IEEE Standard 515-2004.
The information input to and/or generated from Compu- Trace can be printed and summary reports, including “load chart” information, exported for use in other programs. While CompuTrace is a valuable asset to use in designing a heat tracing system, the design steps detailed in this guide will still form the basis for identifying the design process necessary to establish a properly functioning heat tracing system.